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HomeMy WebLinkAboutSWP273635(13) AC1522R-10 �s p (Reapproved 2011) C 0�Gam" (01A - �73 0L Report on Pervious Concrete Reported by ACI Committee 522 v • • "IonAmerican Concrete Institute° opyrif;M American Concrete Institute mvitled by IHS urger Ncense witO ACI Lltencee.CH2M HNI Wpywlde/59g615000g,Uxr.Troyan,Sean oreproduction Or nenvorkfng pertnl;tetl vMhout.Icense!rom IHS Not for Resale,012gIt015 12:00.07 MST E r First Printing March 2010 American Concrete Institute" Aduuncing concrete knowledge Report on Pervious Concrete Copyright by the American Concrete Institute, Farmington Hills, MI. All rights reserved. This material may not be reproduced or copied, in whole or part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of ACI. The technical committees responsible for ACI committee reports and standards strive to avoid ambiguities, omissions, and errors in these documents. 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Phone: 248-848-3700 Fax: 248-848-3701 www.concrete.org ISBN 978-0-87031-364-6 Copyright American Concrete Institute Provided by IHS under license v81h ACI Licensee-CH2M Hill 015 12 1507 MS 048.User.Troyan.Sean No reproduction or nemorhmg permitted without license from HIS Not for gesale.01/28/2015 12.09,07 MST ACI 522R-10 (Reapproved 2011) Report on Pervious Concrete Reported by ACI Committee 522 Matthew A.Offenberg Chair Don J.Wade Charles A.Weiss Jr. Vice Chair Secretary William L.Arent Scott Erickson John R.Love IIi Thomas Rozsits Bob J.Banka Dale Fisher Darmawan Ludirdja George W.Seegebrecht William D.Brant Walter Flood Allen Luke David M.Suchorski Heather J.Brown Bruce A.Glaspey Brian Lutey Diep T.Tu Javier Casto Liv Haselbach Kamyar C.Mahboub Christopher Tull Manoj Chopra Omer Heracklis Andrew Marks Robert Louis Varner John Cook Daniel J.Huffman Luis Mata W.Jason Weiss Michael S.Davy John Kevem Nara anan Neithalath Y Kevin Wolf Norbert J.Delatte Frank Lennox Oon-Soo Ooi Peter T.Yen Aly Ibrahim Eldarwish Milan Lipensky Joseph E.Rottman 771is report provides technical information on pervious concrete's application, CONTENTS design methods,materials,properties,mixture proportioning,construction Chapter 1—Introduction and scope, p. 2 methods,testing,and inspection. 1.1—Introduction The term "pervious concrete" typically describes a near-zero-sluntp, 1.2—Scope open-graded material consisting of portland cement, coarse aggregate, little or no fine aggregate, admixntres, and water. The combination of these ingredients will produce a hardened material with connected pores, Chapter 2—Notation and definitions, p. 3 ranging in size from 0.08 to 0.32 in.(2 to 8 nim),that allow water to pass 2.1—Notation through easily. The void content can range from 15 to 35%, with typical 2.2—Definitions compressive strengths of 400 to 4000 psi(2.8 to 28 MPa). The drainage rate of pervious concrete pavement will vary with aggregate size and Chapter 3—Applications, p. 3 density of the mixture,but will generally fall into the range of 2 to 18 gal./ 3.1—General nlinlft2(81 to 730 Urnollm2).Pervious concrete is widely recognized as a sustainable building material, as it reduces stornavater runoff; improves 3.2—Building applications:history stormwater quality, may recharge groundwater supplies, and can reduce 3.3—Pavement applications the impact of the urban heat island effect. 3.4—Other applications Keywords:construction;design;drainage;green building;LEED®credit; Chapter 4—Materials, p. 6 permeability;pervious concrete pavement;stormwater;sustainability;testing. 4.1—General 4.2—Aggregates 4.3—Cementitious materials ACI Committee Reports,Guides,Manuals,and Commentaries 4.4—Water are intended for guidance in planning, designing, executing, 4.5—Admixtures and inspecting construction.This document is intended for the use of individuals .who are competent to evaluate the Chapter 5—Properties, p.7 significance and limitations of its content and recommendations 5.2—General and who will accept responsibility for the application of the material it contains.The American Concrete Institute disclaims 5.2—Compressive strength any and all responsibility for the stated principles.The Institute shall not be liable for any loss or damage arising therefrom. ACI 522R-10 supersedes AC[ 522R-06 and was adopted and published March Reference to this document shall not be made in contract documents.If items found in this document are desired b the zolo. Y Copyright©2010,American Concrete Institute. Architect/Engineer to be a part of the contract documents,they All rights reserved including rights of reproduction and use in any form or by any shall be restated in mandatory language for incorporation by means, including the making of copies by any photo process, or by electronic or the Architec[fEngineer. mechanical device,printed,written,or oral,or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device,unless permission in writing is obtained from the copyright proprietors. opynght American Concrete Insiltule rovided by IHS under license with ACI Licensee.CH21V!Hill Worldwide/596045E046,User.Troyan,Sean o reproduction or networking permitted without license from INS Not for Resale,Of 12&2015 12.09:07 MST 2 REPORT ON PERVIOUS CONCRETE(Act 522R-10) 5.3-Flexural strength 11.7-Environmental filtering/re mediation potential 5.4-Void content/density 11.8-Surface deterioration and repair 5.5-Pore sizes 11.9-Development and standardization of broader 5.6-Percolation rate testing methods 5.7-Durability 11.10-Non-destructive determination of performance 5.8-Toughness and properties 5.9-Acoustic absorption 11.11-Urban heat island effect, carbonation, and other thermal properties Chapter 6-Pervious concrete mixture 11.12-Other novel applications and uses proportioning, p. 12 6.1-General Chapter 12-The environment and pervious 6.2-Materials concrete, p. 33 6.3-Water-cementitious material ratio 12.1-Pervious concrete and the LEEDTM green building 6.4-Void content rating system 6.5-Amount of coarse aggregate 6.6-Paste volume,cement,and water contents Chapter 13-References, p.36 6.7-Proportioning procedure 13.1-Referenced standards and reports 6.8-Typical ranges of materials 13.2-Cited references Chapter 7-Pervious pavement design, p. 15 CHAPTER 1-INTRODUCTION AND SCOPE P P 1.1-introduction 7.1-Introduction This report provides technical information on pervious 7.2-Structural design concrete's application, design methods, materials, properties, 7.3-Stormwater management design mixture proportioning, construction methods, testing, and 7.4-Other considerations inspection. Chapter 8-Pervious pavement construction, p. 20 The term "pervious concrete" typically describes anear- zero-slump, open-graded material consisting of portland 8.1-General construction principles cement, coarse aggregate, little or no fine aggregate, 8.2-Subgrade/subbase preparation admixtures,and water.The combination of these ingredients 8.3-Placing will produce a hardened material with connected pores 8.4-Consolidation (Fig. 1.1),ranging in size from 0.08 to 0.32 in. (2 to 8 mm), 8.5-Jointing that allow water to pass through easily.The void content can 8.6-Curing and protection range from 15 to 35%,with typical compressive strengths of 8.7-Cold weather protection 400 to 4000 psi (2.8 to 28 MPa). The drainage rate of 8.8-Hot weather protection pervious concrete pavement will vary with aggregate size 8.9-Repairing pervious concrete pavements and density of the mixture, but will generally fall into the 8.10-Maintenance range of 2 to 18 gal./min/ft'`(81 to 730 L/min/m2)or 192 to 1724 in./h(0.14 to 1.22 cm/s). Chapter 9-Quality control inspection and testing, p.26 1.2-Scope 9.1-General Concern has been growing in recent years toward reducing 9.2-Preconstruction inspection and testing the pollutants in water supplies and the environment. In the 9.3-Inspection and testing during construction 9.4-Post-construction inspection and testing Chapter 10-Performance, p. 27 v 10.1-General 10.2-Changes in infiltration rates 10.3-Structural distress " 10.4-Surface distress r 10.5-Resistance to freezing and thawing Chapter 11-Limitations, potential applications, and research needs, p.29 11.1-Pervious concrete in cold climates 11.2-Strength determinations and limitations 11.3-Characterization of the material structure - 1 1.4-Freezing-and-thawing and cold climate applications p 11.5-Porous grout 11.6-Stormwater management Fig. 1.1-Pervious concrete pavement texture on parking tat. Copyright American Concrete InsStoe American Concrete Institute Co ri a '^ Prodded by IHS under license wil PY 9 hl.�h ACI censee.CH2M HIII Worrdweler596045e046,User.Troyan,Sean No reproduction or networking permmed wilhoul license from IHS Not for Nesale,O1I2612015 12:09:07 MST PERVIOUS CONCRETE 522R-3 1960s, engineers realized that runoff from developed real pavement, pervious—a pavement comprising material estate had the potential to pollute surface and groundwater with sufficient continuous voids to allow water to pass from supplies.Further,as land is developed,runoff leaves the site the surface to the underlying layers. in higher rates and volumes,leading to downstream flooding percolation rate—the rate, usually expressed as inches and bank erosion. Pervious concrete pavement reduces the per hour or inches per day, at which water moves through impact of development by reducing or eliminating storm- pervious concrete. water runoff rates and protecting water supplies. porosity—the volume of open and connected interstitial void space in pervious concrete. CHAPTER 2—NOTATION AND DEFINITIONS raveling—the wearing away of the concrete surface 2.1—Notation caused by the dislodging of aggregate particles. A = area of the pavement,acre(m2) runoff—water from rain or snow that is not absorbed into b = solid volume ft3(m3) coarse aggregate in a unit volume the ground but instead flows over less pervious surfaces into of concrete,ft (m ) streams and rivers. bo = solid volume of coarse aggregate in a unit volume surface course the top layer of a concrete pavement of coarse aggregate,ft3(m3) structure. b/bo = dry-rodded volume of coarse aggregate in a unit void content—the ratio of the volume of voids,including volume of concrete both entrapped and entrained air, to the total volume C = runoff coefficient expressed as a percentage. c = cement content,lb(kg) dt = thickness of the pavement, ft(m) CHAPTER 3—APPLICATIONS d2 = thickness of the subgrade,ft(m) 3.1—General f� = specified compressive strength of concrete, psi Pervious concrete has been used in a wide range of (MPa) applications,including: f, = modulus of rupture of concrete,psi(MPa) Pervious pavement for parking lots(Fig.3.1); t = time,seconds Rigid drainage layers under exterior mall areas; ht = initial head,in.(mm) 0 Greenhouse floors to keep the floor free of standing water, h2 = final head,in. (mm) Structural wall applications where lightweight or better k = permeability,in./s (mm/s) thermal insulation characteristics,or both,are required; m' pt = percentage of void space in the pavement 0Pavements, walls, and floors where better acoustic P2 = percentage of void space in the subgrade absorption characteristics are desired; R = pressure reflection coefficient Base course for streets,roads,driveways,and airports; V,, = aggregate volume,ft3(m3) Surface course for parks and tennis courts; V, = cement volume,ft3(m3) Floors for zoo areas and animal barns and stalls; Vp = paste volume; total of cement and water volume, Bridge embankments; ft3(m3) Swimming pool decks; Vp = available storage in pavement,ft3(m3) V,. = required storage volume,ft3(m3) � -<�---- ----- 1; = available storage in subgrade,ft3(m3) Vs = total solid volume of aggregate, cement, and water,ft3(m3) y '} Vtot = total volume,ft3(m3) i V,,, = water volume,ft3(m3) WQ = dry aggregate weight, lb(kg) Wssd = saturated surface-dry weight, lb(kg) w = water content, lb(kg) t� � I U. = absorption coefficient 2.2—Definitions ACI provides a comprehensive list of acceptable definitions III through an online resource, "ACI Concrete Terminology," http://tenuinalogy.concrete.org. Definitions provided here E complement that resource. concrete,pervious—hydraulic cement concrete propor- tioned with sufficient interconnected voids that result in a highly permeable material,allowing water to readily pass. impervious area—an area covered by a material that prevents precipitation from infiltrating soils and recharging groundwater supplies. Fig..3.1—Parking lot built with pervious concrete pavement. ,opyrlght American Concrete!nsti!ute "O'ded by IHS under license'Mth ACI Licensee-CH210 Hill Worldwidei5960456046,User.Troyan,Sean Jo reomducllon or networking pennined without license from IHS Not for Resale.01 2112015 12 09.07 MST 522R-4 ACI COMMITTEE REPORT • Beach structures and seawalls; • Sewage treatment plant sludge beds; • Solar energy storage systems; • Wall linings for drilled water wells; and • Artificial reefs where the open structure of pervious concrete mimics the reef structure. , Typically, unreinforced pervious concrete is used in all these applications because of the high risk of reinforcing steel corrosion due to the open pore structure of the material. r 3.2—Building applications: history Pervious concrete has been used in building construction since at least the middle of the nineteenth century (Francis 1965).Throughout this chapter,the term"pervious concrete" Fig. 3.2— Pervious concrete pavement used within the drip is used to describe the material,but in the references and histor- line of tree. ically, it may have been described as no-fines concrete or gap-graded concrete.European countries have used pervious Pervious concrete was extensively used for industrial, concrete in different modes:cast-in-place load-bearing walls public, and domestic buildings in areas north of the Arctic in single- and multistory houses and, in some instances, in Circle because traditional building materials proved high-rise buildings, prefabricated panels, and steam-cured impracticable. Examples of these impracticalities include blocks. In 1852, pervious concrete was first used in the the high transportation costs of brick, fire hazards of construction of two houses in the United Kingdom(UK).This timber, and poor thermal insulation properties of plain concrete consisted of only coarse gravel and cement.It is not concrete(Malhotra 1976). mentioned in the published literature again until 1923,when a Although pervious concrete has been used in Europe and group of 50 two-story houses were built with clinker aggregate Australia for the past 60 years,its use as a building material in Edinburgh, Scotland. In the late 1930s, the Scottish in North America has been extremely limited.One reason for Special Housing Association Limited adopted the use of this limited use is,after World War II,North America did not pervious concrete for residential construction. By 1942, experience a materials shortage as much as Europe. pervious concrete had been used to build over 900 houses. In Canada,the first reported use of pervious concrete was From 1939 to 1945,the havoc of World War 11 left almost in 1960. Pervious concrete was used in the construction of all of Europe with vast housing needs,which encouraged the some houses in Toronto and on a nonstructural basis in a development of new or previously unused methods of federal building in Ottawa. building construction. Notably among them was pervious concrete (Malhotra 1969). Pervious concrete used less 3.3—Pavement applications cement per unit volume of concrete as compared with Pervious concrete pavements'advantages over conventional conventional concrete, and the material was advantageous concrete pavements include: where manpower was scarce or expensive. Over the years, Controlling stormwater pollution at the source; the pervious concrete system contributed substantially to the Increasing facilities for parking by eliminating the need production of new houses in the UK, Germany, Holland, for water-retention areas; France, Belgium, Scotland, Spain, Hungary, Venezuela, Controlling stormwater runoff; West Africa, the Middle East, Australia, and Russia. Reducing hydroplaning on road and highway surfaces; Germany used this system because disposal of large quantities 0 Creating additional lift to aircraft during takeoff due to of brick rubble was a problem after the war, leading to the cooling effect; research into the properties of pervious concrete.Elsewhere, Reducing glare on road surfaces to a great extent, the unprecedented demand for brick and the subsequent particularly when wet at night; inability of the brick-making industry to provide an adequate Reducing the interaction noise between tire and pavement; supply,led to the adoption of pervious concrete as a building Eliminating or reducing the size of storm sewers;and material.Similarly in Scotland,between 1945 and 1956,many Allowing air and water to reach tree roots, even with homes were built with pervious concrete.This was mainly due pavement within the tree drip line(Fig. 3.2). to the presence of unlimited supplies of hard aggregates and Pervious concrete pavements'potential disadvantages and the absence of good facing bricks. The first reported use of challenges include: pervious concrete in Australia was as early as 1946. Limited use in heavy vehicle traffic areas; Before World War II,production of pervious concrete was Specialized construction practices; confined to two-story homes.After 1946,however,pervious Extended curing time; concrete was used for a much broader range of applications. Sensitivity to water content and control in fresh concrete; It was specified as a material for load-bearing elements in Special attention and care in design of some soil types buildings up to 10 stories tall(Francis 1965). such as expansive soils and frost susceptible ones; Copyright American Concrete Insutute Provided by IHS under license with ACI Llcensee.CH2M 1,101 Warldwidei5960458046.tlser.Troyar.Sean No reproduction or networking pen deo without,tense!rom IHS Not for Resale.01/282015 12:09:07 MST PERVIOUS CONCRETE 522R-5 • Lack of standardized test methods; and (BMPs)as a way for communities to mitigate the problem of • Special attention possibly required with high groundwater. stormwater runoff.Pervious concrete parking lots have also Engineers have specified pervious concrete in pavements as: been selected as an integral solution to the problem of hot + Surface course; pavements in the Cool Communities program. The air • Permeable base and edge drains; and temperature over pervious concrete parking lots is generally • Shoulders. cooler than asphalt. Pervious concrete parking lots also The success of pervious pavement systems has been reduce snow and ice buildup and are considered a nonpollutant mixed. In some areas, pervious concrete pavement systems to the environment.The practical range of design thicknesses have been applied successfully,whereas in others they have for pervious concrete pavements is from 5 to 12 in. (125 clogged in a short time. Many failures can be attributed to to 300 mm)for plain parking lots. contractor inexperience, higher compaction of soil than 3.3.1.2 Roadways—Pervious concrete for roadways is specified,and improper site design. For a pervious concrete usually considered for two applications as a: pavement to work successfully: 1. Drainable base,or subbase material; and • Permeability of soils should be verified. A percolation 2.Roadway surface or friction course. rate of 0.5 in./h(13 mm/h)and a soil layer of 4 ft(1.2 m) In both categories,although the drainage characteristics are or more are generally recommended. There are installa- required properties, strength requirements may vary tions of pervious concrete and other porous paving depending on the location of the material in the pavement materials. In the red-clay Piedmont regions of the section.The practical range of design thicknesses for pervious Carolinas and Georgia, however, where the subgrade concrete is from b to 12 in.(150 to 300 mm)for plain roadway infiltration rate is much less than 0.5 in./h (13 mm/li), pavements.Bonded overlays(Maynard 1970),however,have these pavements facilitate infiltration and filtering of been as thin as 2 in. (50 mm). Many highways in Europe are runoff and recharging of groundwater(although they do being constructed using an overlay of latex-modified pervious not infiltrate all of the rain water in large storms); concrete that allows for pavement drainage and tire-noise • Construction site runoff and heavy equipment should reduction.The latex modification results in better mechanical be kept from entering the pervious pavement area.The properties(Pindado et al. 1999). pervious concrete pavement should not be placed into 3.3.2 Permeable bases and edge drains--A pervious service until all disturbed land that drains to it has been concrete base drains water that would normally accumulate stabilized by vegetation. Strict erosion and sediment beneath a pavement.This type of construction helps to reduce OAKZ controls during any construction or landscaping activity pumping of subgrade materials that could lead to the failure of are essential to prevent the system from clogging and the pavement.In some states,the departments of transportation should be incorporated into the construction site storm- have created standards for constructing drainable bases and water management plan; and edge drains using pervious concrete. California, Illinois, • Construction traffic (primarily vehicular) should be Oklahoma, and Wisconsin have such standard specifications directed away from the pervious pavement area during (Mathis 1990). Pervious concrete in these applications is construction to prevent compaction of underlying soil usually lower strength(1000 psi [7 MPa]or less),and is used layers and loss of infiltrative capacity. in conjunction with a nonwoven geotextile fabric. A similar 3.3.1 Surface coin-se—Pervious concrete may be used as a system can be used in slope stabilization. surface course for parking lots and minor road strips(Fig.3.1). 3.3.3 Shoulders—Pervious concrete shoulders have been Use in the U.S.,to a large extent,has been in surface courses. used in France in an effort to reduce pumping beneath Many parking lots in Florida consist of a pervious concrete concrete pavements, Air-entraining admixtures are used to surface course.Its use in Florida is due to three factors: increase resistance to freezing and thawing.Porosities on the 1.Florida frequently encounters heavy storms that cause a order of 15 to 25% have been found to nearly eliminate the quick accumulation of large amounts of stormwater; the use risk due to freezing,unless the concrete is allowed to become of pervious concrete reduces the runoff volume; saturated.Compressive strengths are often less than 2000 psi 2. Designers prefer the stormwater be retained on-site to (14 MPa)at 28 days. recharge the groundwater system;and 3. The cost effectiveness of using pervious concrete over 3.4—Other applications conventional pavements is greatly enhanced with the 3.4.1 Drains—Water and power resources services have elimination of storm sewers. used pervious concrete for the construction of permeable 3.3.1.1 Parking lots—Pervious concrete was referred to drain tiles as well as drains beneath hydraulic structures.The as a parking lot paving material in the central Florida area as drains relieve uplift pressures and allow groundwater to be early as the 1970s(Medico 1975).The concept developed as drained from beneath sewer pipes. a means of handling the enormous quantities of water 3.4.2 Greenhouses—The use of pervious concrete as a running off a parking lot during a storm; pervious concrete thermal storage system in greenhouse floors has been allows the water to percolate into the ground under the investigated by researchers (Monahan 1981; Herod 1981). pavement.The Environmental Protection Agency(EPA)has The floor served as a storage area as well as a heat exchanger adopted a policy that recommends the use of pervious for the solar-heated greenhouse. Pervious concrete has also pavements as a part of their Best Management Practices been used-as paving in greenhouse floors to keep water from 3opyrlghl American Concrete Institute 'rovlded by IHS under license with ACI Ucensee+C142M H91 Wo!Wwidtu5960458048,User.Troyan,Sear Jo reproduction or networking permined without licerse from IHS Not for Resale.01,2822015 12.09.07 MST 52211-6 ACI COMMITTEE REPORT ponding and to eliminate the growth of weeds while or clay,or other absorbed chemicals that might detrimentally providing a durable,hard surface for moving equipment. affect the paste/aggregate bond or cement hydration.Aggregate 3.4.3 Tennis courts—Pervious concrete has been used sources with a service record of acceptable performance are extensively for the construction of tennis courts in Europe. preferable. In the absence of a source with an acceptable # Pervious concrete slabs allow water to permeate and then drain service record,a combination of tests could be conducted to through a gravel base to the edges of the slab.Fly ash is included provide a basis for assessing the suitability of a candidate in some of the mixtures to increase the workability. aggregate for incorporation into a pervious concrete mixture. 3.4.4 Noise barriers and building walls—Noises from Unit weights of aggregates should be determined in accordance various traffic sources or occupants of a building can be with ASTM C29/C29M. problematic. Pervious concrete noise barriers and interior For new, unknown aggregate sources, results of tests walls are sometimes constructed to reduce noise.This open- conducted as per ASTM C33/03M and D448 should be graded structure tends to absorb and dissipate the sound in reviewed with the input of an experienced materials engineer. the material rather than reflecting it to another location. Examining untested samples by an experienced petrographer can prove to be invaluable in identifying characteristics such CHAPTER 4—MATERIALS as quality,hardness,degree of weathering,and the presence 4.1—General of deleterious coatings that could impair the performance of Pervious concrete, also known as no-fines, permeable, or the material in service. enhanced porosity concrete (EPC), usually consists of Aggregate moisture at time of mixing is important. The normal portland cement, uniform-sized coarse aggregate, aggregate absorption should be satisfied by conditioning the and water. This combination forms an agglomeration of stockpile as necessary to achieve saturated surface-dry(SSD) coarse aggregates surrounded by a thin layer of hardened condition.Otherwise,a dry aggregate may result in a mixture cement paste at their points of contact. This configuration that lacks adequate workability for placing and compaction. produces interconnected voids(typically of sizes in the range Overly wet aggregates can contribute to draining of the paste, of 0.04 to 0.2 in. [I to 5 mm])between the coarse aggregate, causing intermittent clogging of the intended void structure. which allows water to permeate at a much higher rate than conventional concrete. Pervious concrete is considered a 4.3—Cementitious materials special type of highly porous concrete.Such porous concrete Portland cement conforming to ASTM C 150/C150M, can be classified into two types: one where the porosity is C595/C595M, or C1157/C1157M is used as the main binder. present in the aggregate component of the mixture (light- Supplementary cementitious materials such as fly ash, weight aggregate concretes), and one where porosity is ground-granulated blast-furnace slag, and silica fume can introduced in the nonaggregate component of the mixture also be used in addition to portland cement and should meet (pervious concrete) (Neithalath 2004). Lightweight aggregate the requirements of ASTM C618, C989, and C1240, concrete can be constructed by using extremely porous respectively. Testing materials in trial batching is strongly natural or synthetic aggregates. Pervious concrete has little recommended to verify that cement-admixture compatibility or no fine aggregate in the mixture. Another distinction is not a problem and that the setting time, rate of strength between these two types of porous concrete is based mainly development, porosity, and permeability can be achieved to on the void structure. Lightweight aggregate concretes provide the characteristics needed for the anticipated placement contain large percentages of relatively nonconnected voids. and service conditions. Pervious concrete, however, contains high percentages (20 to 35%)of interconnected voids,which allows for the rapid 4.4—Water passage of water through the body of concrete. Water quality for pervious concrete is governed by the same requirements as those for conventional concrete. Pervious 4.2—Aggregates concretes should be proportioned with a relatively low water- Aggregate gradings used in pervious concrete are typically cementitious material ratio (w/cm) (typically 0.26 to 0.40) either single-sized coarse aggregate or grading between 3/4 because an excess amount of water will lead to drainage of the and 3/8 in.(19 and 9.5 mm).Rounded and crushed aggregates, paste and subsequent clogging of the pore system. The both normal and lightweight, have been used to make addition of water,therefore,has to be monitored closely in the pervious concrete..The aggregate used should meet field.Further discussion of water quality is found in ACI 301. requirements of ASTM D448 and C33/03M.Fine aggregate Recycled water from concrete operations may be usable but content is limited in pervious concrete mixtures because it only if it meets provisions of ASTM C94/C94M or AASHTO tends to compromise the connectedness of the pore system. M-157. The addition of fine aggregate may increase compressive strengths and density but correspondingly reduce the flow 4.5—Admixtures rate of water through the pervious concrete mass. Water-reducing admixtures should meet the requirements Aggregate quality in pervious concrete is equally important of ASTM C494/C494M. Water-reducing admixtures (high- as in conventional concrete. Flaky or elongated particles range or medium-range) are used depending on the w/cm. should be avoided. The narrow-graded coarse aggregate Retarding admixtures are used to stabilize and control cement should be hard and clean,and free of coatings,such as dust hydration. Retarding admixtures are frequently preferred Copynghl American Concrete Institute PToed by IHS under license with ACI Licensee-CH2M H41 Worldwide/5960458046,User-Troyan.Sean No reproduction or networking permitted without license from HIS Not for Resale.01128 2015 1 2.09 07 MST PERVIOUS CONCRETE 522R-7 when dealing with stiff mixtures,such as pervious concrete, Cylinder compressive strength They are especially useful in hot weather applications, versus air content Retarding admixtures can act as lubricants to help discharge 0000 — concrete from a mixer and can improve handling and in- • • place performance characteristics. Accelerators can be used _ 5000 when pervious concretes are placed in cold weather.Studies a report the use of cement hydration stabilizers as an aid in a1 a000 extending the working time of the mixture and viscosity- '•' modifying admixtures (VMAs) to enhance workability; these m 3000 • advantages have also been witnessed during actual production H •`t and placements for projects. With the use of multiple 2 2000 admixtures in any concrete mixture, it is recommended that •� a trial mixture placement is conducted to identify any U 1000 admixture incompatibility problems and verify desired fresh and hardened properties are consistently achievable. 0 li Air-entraining admixtures should meet the requirements 50 100 150 2100 250 300 of ASTM C260.Air-entraining admixtures are not commonly Air content,%in cylinders used in pervious concretes,but can be used in environments Fig. 5.1—Relationship between air content and compressive susceptible to freezing and thawing. No reliable method strength for pervious concrete (Meininger 1988) (1 psi = exists,however,to quantify the entrained air volume in these 0.006895 MPa). materials. Research is currently underway on the resistance to freezing and thawing of pervious concrete mixtures, and Cylinder compressive strength versus unit weight most studies involve the use of an air-entraining agent 300° (Neithalath et al. 2005a; Schaefer et al. 2006; Baas 2006). Until a greater body of research is available, it may be 6r a prudent to include an air-entraining admixture where placement occurs in colder climates.This is reportedly true in relatively ,500 higher cement content mixtures where the paste thickness a �4-FE. �'44�',' coating aggregate particles exceeds 0.008 in. (200 Vim). two " t , Incorporation of fibers for mixtures to be exposed to freezing and thawing has shown success in some studies to improve �,s durability in cold climates. 109 toe 110 112 114 lie tie 120 122 124 The use of construction specialty chemicals is also reported unit weight IW to be beneficial when windy,drying ambient conditions create Fig 5.2---Relationship between unit weight and compressive high evaporation rates that reduce the window of time when a strength for pervious concrete (Mulligan 2005) (1 psi = mixture is most efficiently placed. The use of evaporation 0.006895 MPa; 1 lb/ft'= 16.02 kglm'). retarders may be helpful in this regard. CHAPTER 5—PROPERTIES 5.2—Compressive strength 5.1—General The compressive strength of pervious concrete is strongly The various properties of pervious concrete are primarily affected by the mixture proportion and compaction effort dependent on its porosity (air void content), which in turn during placement.Figure 5.1 shows the relationship between depends on cementitious content,w/cm,compaction level,and pervious concrete compressive strength and air void content aggregate gradation and quality.The pore sizes in the material (Meininger 1988).Figure 5.1 is based on a series of laboratorytests where two sizes of coarse aggregate were used and also impact strength properties. Although pervious concrete compaction effort and aggregate gradation were varied. has been used for paving for more than 20 years in the U.S., Figure 5.2 (Mulligan 2005) shows a relationship between only a few investigations have been done to determine perfor- pervious concrete compressive strength and unit weight.The mance(Ghafoori 1995;Wanielista et al.2007).Investigations figure is based on another series of laboratory tests where have been based primarily on laboratory tests,with some data one size of coarse aggregate was used and compaction effort from actual field installations obtained. Only one ASTM and the aggregate-cement ratio was varied.Figure 5.1 shows method exists that is specifically intended for use on pervious that relatively high compressive strengths of pervious concrete. ASTM Subcommittee C09.49 is developing test concrete mixtures are possible, but the high strength is methods for compressive strength, flexural strength, in-place achieved only with the reduction of air void content. This density/porosity, and in-place permeability. The specifier results in a loss in percolating efficiency of pervious should use caution when referencing test methods for concrete. It has been reported that an I I% decrease in pervious concrete that are intended for plain concrete. compressive strength was observed when the vibration :opyrlght American Concrete Institute Yovided by!HS under license with ACI Ucensee.CH2M Hill War dwld&596C458049.User.?myan,Sean to reproduction or retwork'.ng perm tied m1hout'.Icense from IHS Not for Resale.01+2&2015'2.09 07 MST 522R-8 ACI COMMITTEE REPORT Air content for two compaction levels Flexural versus compressive strength 790 — -- — � 35.0 /^1 • coo 30.0 • c 500 ' 25.0 � , • ♦ . • • • 400 20.0 .� o 300 LL •� a 15.0 • 0.25 0.35 0.45 0.55 Water-cemenikloua materiel ratio(Hfcm) EJ 109 Fig.5.3—Relationship between air content and compaction o tcoo z000 aoa9 th, soo9 eoa9 1� 1� Compressive atronpth,psi energy for pervious concrete(Meininger 1988). Fig. 5.5 Relationship between flexural strength and compressive strength for pervious concrete (Meininger Beam flexural strength versus air content 1988)(1 psi=0.006895 MPa). sew (with cement and aggregate content held constant) at two 500 different compaction levels.Experience has shown that a w/cm ;:. of 0.26 to 0.45 provides good aggregate coating and paste 40o stability.When fine aggregates are used in pervious concrete : • proportioning,the grain size of the fine aggregate in relation > 300 ' •• '• to the coarse aggregate is believed to influence the porosity ' and,consequently, the compressive strength of the material LL (Onstenk et al. 1993). The total cementitious material content of a pervious concrete mixture is important for the development of 100EE compressive strength and void structure.An excessive paste 50 100 150 200 250 300 content may result in a filled void structure and,consequently, Air content,%in beams reduced porosity. An insufficient cementitious content can Fig. 5."elationship between air content and flexural result in reduced paste coating of the aggregate and reduced strength for pervious concrete (Meininger 1988) (1 psi = compressive strength. The optimum cementitious material 0.006895 MPa). content is strongly dependent on aggregate size and gradation. For the aggregate size chosen, binder drainage tests are amplitude of the compactor is reduced to 0.0034 in. (0.086 recommended to be carried out to ascertain the optimum mm)from 0.005 in. (0,127 mm) (Suleiman et al.2006). An cementitious content(Nelson and Phillips 1994). increase in aggregate size has been reported to result in Another factor that can have a significant impact on the reduced compressive strength, while polymer additives and strength of pervious concretes is the thickness of the paste mineral admixtures have been found to increase the layer surrounding the aggregate.This is related to the aggregate compressive strength for the same aggregate gradation (Jing size,cementitious material content,and the w/cm. and Guoliang 2003), Crouch et al. (2006) reports that an increase in fineness modulus of the aggregates reduces the 5.3—Flexural strength compressive strength. Mahboub et al. (2008) cautions that Figure 5.4 (Meininger 1988) shows the relationship Feld cored strengths can be significantly different than cast between pervious concrete flexural strength and air void test cylinders. content based on beam specimens tested in the same series of Although the w/cm of a pervious concrete mixture is laboratory tests described for Fig.5,1.Although these results important for the development of compressive strength and are based on a limited number of specimens,comparing the void structure, the relationship between the w/cm and data in Fig. 5.1 and 5.4 indicates that a relationship between compressive strength of conventional concrete does not the compressive and flexural strengths of pervious concrete apply to pervious concrete properties.A high w/crn can result exists.This relationship,like compressive strength,depends in the paste flowing from the aggregate, filling the void on several variables.Figure 5.5(Meininger 1988)shows the structure. A low w/cm can result in reduced adhesion relationship between compressive and flexural strengths of between aggregate particles and placement problems. pervious concrete for one laboratory test series. Another Figure 5.3(Meininger 1988)shows the relationship between series of test data relating the flexural strength and porosity the w/cm and air void content of a pervious concrete mixture is shown in Fig 5.6(Neithalath 2004). Copyright American Concrete Institute Provided by MS under license with ACI Ucensee.CH2M HI WorldwMa%5960458046,User-Troyan,Sean No reproduction or networking penIteo wimout kcense hom IHS Not for Resale,01128/2015 12:09.07 MST PERVIOUS CONCRETE 522R-9 4.0 • 40—-- - - - #4 aggregates • 3/8"aggregates M 3.6 • R2=0.52 0 30 L • co 3.2 c • o i 0820 2.8 • 0 7 • 61 � X Q 10— d 2.4 LL 2.0 0 — -- -- 10 20 30 40 0 25 50 75 100 Porosity (%) Percentage of#8 aggregates Fig. 5.6--Relationship between flexural strength and Fig. 5.7—Influence of aggregate size and gradation on the porosity for pervious concrete(I psi= 0.006895 MPa). porosity of pervious concretes. The addition of a small amount of sand (approximately 5% The influence of aggregate gradation on porosity for by volume)increases the flexural strength of pervious concrete laboratory prepared pervious concrete specimens is shown (Neithalath 2004).An increase in flexural strength of pervious in Fig.5.7.A range of porosities can be obtained by blending concrete has been reported when a polymer additive is used aggregates of two different sizes (Neithalath 2004). Care (Onstenk et al. 1993).Flexural tensile strength of about 535 psi should be taken to ensure that the aggregate size ratio(ratio (3 MPa) has been observed for a pervious concrete propor- of the diameter of the larger aggregate to that of the smaller tioned using 1/4 to 3/8 in.(6 to 10 mm)aggregates and having one) is not very large when using aggregate blends. If the 25%porosity(Nissoux et al. 1993;Brite/Euram Report 1994). ratio is very high(typically 2.5 or more), the smaller aggre- Crouch et al. (2006)investigated the relationship between gate will fill the voids left by the larger one, reducing the flexural stren thfrand compressive strength c' for pervious porosity and, consequently, the permeability. Though the pavement. They determined that the relationship most mechanical properties are enhanced using blends with large closely matches the equation established by Ahmad and size ratios,it is generally not recommended because pervious Shah(1985)for precast concrete. concretes are primarily designed for water permeation. Compactive effort has an influence on the void content, fr=2.3f,2/3 (in.-lb units) (5-1) porosity, and density of a given pervious concrete mixture. In a laboratory test series (Meininger 1988), a single 2/3 pervious concrete mixture compacted with eight different fr=0.083fc (SI units) levels of effort,produced unit weight values that varied from 105 to 120 lb/ft3(1680 to 1920 kg/m3).Figure 5.2 shows that 5.4—Void content/density this variation of unit weights and related air void content can The density of fresh pervious concrete can be determined have a measurable effect on the compressive strength of by ASTM C1688/C1688M,and is directly related to the void pervious concrete. For constant paste content, the void content of a given mixture. Two additional methods that content is reported to be a function of compactive effort, determine porosity of hardened pervious concrete have been aggregate particle shape and texture,and aggregate uniformity reported (Neithalath 2004). The first method involves a coefficient(Crouch et al.2006). volumetric procedure where the mass of water filling a sealed pervious concrete sample is converted into an equiv- 5.5—Pore sizes alent volume of pores.In the second method,an image anal- The sizes or size range of pores in pervious concrete is also ysis procedure is employed on pervious concrete specimens a major factor influencing its properties. The influence of that have been impregnated with a low-viscosity epoxy pore sizes on water permeability and acoustic absorption has (Marolf et al. 2004). The accessible porosity in a pervious been documented (Neithalath 2004; Neithalath et al. 2006). concrete mixture is a function of the aggregate sizes and rela- To generate larger-sized pores in the material,larger aggregate tive quantities of different sizes in the mixture(Brite/Euram sizes are recommended. Larger-sized pores are recommended Report 1994).The image analysis procedure is advantageous in because they may reduce the chances of pore-clogging ascertaining the variation in porosity with depth of a pervious (Nelson and Phillips 1994). Figures 5.8 and 5.9 depict the concrete specimen or layer. influence of single-sized aggregates as well as blending two Void content is highly dependent on several factors: different aggregate sizes in varying proportions on the pore aggregate gradation, cementitious material content, w/cm, sizes of pervious concrete.Replacing smaller-sized aggregates and compactive effort. with an increasing percentage of larger-sized ones increases .opyrlghl American Concrete Institute 'ro-ded oy IHS under license with ACI Ucensee.CH2M HIII Wo4dwidei5960456046,User-Troyan,Sean Jo reproducl oln or networking permitted without•tense from IHS Not!or Resale,012li 12.09 07 MST 522R-10 ACI COMMITTEE REPORT 6 _______ __ Water percolation versus air content 100 E Dp a 1.44+0.36R0egg • 90 -- • 1� E R2=0.93 � • 80 N 4 c 70 p , c 60 u ■ `o so . 40 w 2 + + #8 ou ■ #4 a 30 0 3/8" 20 • .c tl .�• 0 0 0 2 4 6 8 10 00 100 200 300 400 Aggregate size(mm) Air content,%in cylinders Fig.5.8—In1hience of aggregate.size on the pore size of single- Fig. 5.10—Relationship henveen air content and percolation sized aggregate pervious concrete mixtures. rate f nr perl concrete (Meininger 1988) (1 psi = 0.06895 MPa). 6 The scale parameter of the Weibull distribution was used to 3t8"replacing#4 describe the"characteristic pore area"or"characteristic pore E 5 ----- #4 replacing#8 size"of pervious concrete. d N Aggregate size ratio:2.0 5.6—Percolation rate 0 4 One of the most important features of pervious concrete is u its ability to percolate water through the matrix.The percolation y + + 10 rate of pervious concrete is directly related to the porosity ` + _ ,- , and the pore sizes.Tests have shown(Meininger 1988)that t 3 0a minimum porosity of approximately 15% is required to t} v • achieve significant percolation.For a porosity of 20 to 25%, • the coefficient of permeability is reported be approximately 2 0.01 m/s (Brite/Euram Report 1994). Another study 0 20 40 60 80 100 (Nissoux et al. 1993)reports a permeability of 0.88 gal./ft2/s Percentage of bigger aggregates (36 L/m'-/s). Figure 5.10 (Meininger 1988) shows the rela- replacing smaller ones tionship between the air void content and percolation rate of Fig.5.9-4nfluence of aggregate blending on the pore size of a pervious concrete mixture. Because the percolation rate pervious concrete. increases as air void content increases and, consequently, the pore size.This is because the introduced coarser particle compressive strength decreases, the challenge in pervious may not be able to fit in the void left by the removed finer concrete mixture proportioning is achieving a balance particle(Neithalath 2004;Neithalath et al.2003). between an acceptable percolation rate and an acceptable Pore structure of pervious concrete is instrumental in all compressive strength. the properties and performance characteristics of this material. The permeability of pervious concrete can be measured by a Low et al. (2008) outlined a statistical approach to the simple falling-head permeameter as shown in Fig. 5.11 determination of factors influencing pore structure features (Neithalath et al. 2003). In this approach, the sample is such as porosity and pore connectivity factor,and performance enclosed in a latex membrane to avoid water flowing along the characteristic (permeability) of pervious concrete. Using a sides of the specimen.Water is added to the graduated cylinder factorial design experiment with four factors(aggregate size, to fill the specimen cell and the draining pipe.The specimen is aggregate-cement ratio, w/cm, and sand-coarse aggregate preconditioned by allowing water to drain out through the pipe ratio), 16 pervious concrete mixtures were proportioned. until the level in the graduated cylinder is the same as the top From a range analysis on the responses,only the first three of the drain pipe. This minimizes any air pockets in the of four factors mentioned dominate the measured responses. specimen and ensures that the specimen is completely saturated. .: An image analysis method on two-dimensional sections of With the valve closed, the graduated cylinder is filled with pervious concrete was used to characterize the pore structure.A water. The valve is then opened, and the time in seconds t two-parameter Weibull distribution was used to model the required for water to fall from an initial head hi to a Final head pore area and pore size distributions of pervious concrete, 112 is measured.The equipment is calibrated for an initial head Copyright American Concrete Institute Pm ided by IHS ince,license with ACI License-Cl Hip Worldwide1980458046.user.Troyan.Sean No reproduction or networking perrnined without license from IHS Not for Resale,01R82015 12 09.07 MST PERVIOUS CONCRETE 522R-11 of 11.6 in. (290 mm)and a final head of 2.8 in. (70 mm).The 1 95 inm� permeability k(in./s[mm/s])can be expressed as M L +, k=A/t — `�where A is a constant equal to 7.7 in. (192 mm). Graduated cylinder A simple triaxial flexible-wall constant-head permeameter was also constructed for determining the permeability of : pervious PCC in the range of 1 to 14,000 in./h(0.001 to 10 cm/s) Drain pipe (Crouch et al. 2006).Constant-head permeability appears to be a function of paste drain down,effective air void content, and void size. The results of the falling-head and constant- To of the to MM head methods agree reasonably for laboratory samples. sample Apart from the porosity and pore size,a crucial factor that influences the permeability of pervious concrete is the pore Sample tortuosity or the degree of connectivity of the pore network. There is no straightforward methodology to measure the O-Ring pore connectivity of pervious concrete. A recent study Valve (Neithalath et al. 2006) investigated the use of electrical impedance-based methods to determine the pore connectivity factor of pervious concretes to link it to the hydraulic characteristics of the material.It is anticipated that the wide- spread use of techniques like X-ray-computed tomography will lead to accurate determination of pore connectivity in Fig. 5.11—Apparatus for measuring permeability of pervious concretes. pervious concrete by a simple falling-head permeameter The environmental benefits of pervious concrete have (Neithalath et al.2003)(1 in. =25.4 mm). been well documented. Deo et al. (2008) investigated the efficiency of pervious concrete in retaining vehicular oil acidic water. The durability of pervious concrete under spills in its material structure using carefully designed freezing-and-thawing conditions is becoming well documented; experiments and modeling.Pervious concrete mixtures with no documented deterioration due to freezing-and-thawing porosities ranging from 13 to 25%were proportioned using cycling in the field is known to exist. two different size aggregates.The oil retention and recovery Limited testing in freezing-and-thawing conditions indicates was experimentally determined on 2 in, (50 mm) slices of poor durability if the entire void structure is filled with water pervious concrete specimens using a partition gravimetric (U.S. Bureau of Reclamation 1947). Other tests, however, method. It was observed that a porosity of 20% is ideal for have shown the pore structure being filled with water has optimal oil retention in the pore structure of the material.An some,but not complete,correlation with the overall results. idealized pore-aperture model was used to develop a A slower freezing condition--one cycle per day as compared modeling framework for the oil retention in pervious with five or six as per ASTM C 666, Procedure A—may concrete.The material parameters as well as the input features allow the water to drain from the pervious concrete, that are most likely to influence the retention and recovery of improving durability(Neithalath et al.2005a).Limited field oil were identified.A genetic programming-based model was data exist on the long-term durability of pervious concrete in used to predict the oil retention in pervious concrete specimens. northern climates(Delatte et al.2007);however,substantial This modeling methodology provides good estimates of oil empirical data support its use from a freezing-and-thawing retention. The performance of the genetic programming- resistance perspective in the Rocky Mountain and Sierra based model was judged in terms of its error statistics. Nevada regions of the western U.S.along with other regions Results obtained from this model were more reliable than of the country where the standard practice is to treat conven- those obtained using a linear regression method with the same tional concrete pavements with air-entraining admixtures for input parameters. The study is expected to lead to further the purposes of resistance to freezing and thawing. Caution tests on optimization of pore structure of pervious concrete should always be exercised when using pervious concrete in for applications including oil retention and water transport, a situation where complete saturation before a hard freeze may occur. 5.7—Durability Tests indicate that entraining air in the cement paste may Durability of pervious concrete refers to the service life improve resistance to freezing and thawing.In the laboratory under given environmental conditions. Physical effects that under ASTM C666/C666M test conditions, non-air- adversely influence the durability of concrete include exposure entrained pervious concrete fails(relative dynamic modulus to temperature extremes and chemicals such as sulfates and drops to less than 60%) in approximately 100 cycles of acids. No research has been conducted on the resistance of freezing and thawing in the chamber(ASTM C666/C666M pervious concrete to aggressive attack by sulfate-bearing or requires a standard 300 cycles for the test). The relative :opyripht American Concrete Institute crowded by IHS under license with ACI tkensee-CH2M HI,Worldwidei5960458046,User.Troyan,Sean Vo eproduclion or networhinp permitted without flcense from IHS Not for Resale,01'28i2015 12.09,07 MST 522R-12 ACI COMMITTEE REPORT Active microphones To evaluate the sound absorption characteristics of pervious concrete, an impedance tube can be used as shown t= in Fig. 5.12(Neithalath 2004; Marolf et al.2004). Cylindrical tt specimens with a diameter of 3.75 in. (95 mm) can be accommodated in the impedance tube.The sample is placed inside a thin cylindrical Teflon sleeve, into which it fits snuggly. The sample assembly is placed against a rigid . backing at one end of the impedance tube,which is equipped with a sound source. A plane acoustic wave is generated by - the sound source and propagates along the tube axis.Micro- phones placed along the tube's length are used to detect the sound wave pressure transmitted to the sample and portion of soundsoure• the wave that is reflected (ASTM E1050). The pressure Sample tocatton reflection coefficient R is the ratio of the pressure of reflected wave to that of incoming wave,at a particular frequency. Fig. 5.12—Impedance tube for measuring the sound The absorption coefficient a is a measure of a material's absorption characteristics of pervious concrete (Neithalath ability to absorb sound. A material with an absorption 2004;Maralf et al.2004). coefficient of 1.0 indicates a purely absorbing material, whereas a material with an absorption coefficient of 0 indicates modulus stays well over 60%, however, for specimens that the material is purely reflective. Normal concrete, for have the paste portion protected by entrained air. Also, example, typically has an absorption coefficient of 0.03 to pervious concrete specimens subjected to slow freezing and 0.05 (Neithalath 2004). Pervious concrete typically has an thawing(one cycle per day)suffered less damage than those absorption range from 0.1 (for poorly performing mixtures) subjected to the ASTM C666/C666M Procedure A test to nearly 1 (for mixtures with optimal pore volume and where it is subjected to five to seven cycles a day(Neithalath sizes). Because the absorption coefficient depends on the et al.2005a). frequency of impinging sound waves,it is important to select Another study shows that partially saturated pervious a proper pervious concrete thickness to minimize sounds of concrete subjected to freezing and thawing in air demonstrated the desired frequency(800 to 1200 Hz is the most objectionable substantially higher durability than those subjected to to the human ear), freezing and thawing under water (Yang et al. 2006). Addition of small dosages of fine aggregate or synthetic CHAPTER 6—PERVIOUS CONCRETE fiber has been reported to increase the freezing-and-thawing MIXTURE PROPORTIONING resistance(Wang et al. 2006). 6.1—General The process of developing mixture proportions for 5.8—Toughness pervious concrete is often repeated trial-and-error efforts. Synthetic fibers can be employed to increase toughness, For example, a series of trial batches may be developed in defined as the energy absorption of concrete after cracking. the laboratory and then tested in the field to ensure expected Toughness can be quantified in one of several test methods, behavior and performance. In general, the overarching such as ASTM C 1399. This test produces a postcracking philosophy of mixture proportioning for pervious concrete is value in psi that relates to the flexural strength of the to achieve balance between voids, strength, paste content, concrete matrix. Product testing of synthetic fibers in beam and workability. Chapter 6 provides methods for trial batch specimens of pervious concrete in accordance with ASTM proportioning of pervious concrete that is intended for use in C1399 demonstrated that fibers 1.5 to 2.0 in.(40 to 50 mm) pavements and other applications where drainage,percolation, in length were the most effective in imparting toughness to or high porosity is needed.The results of the trial batch may the concrete(SI Concrete Systems 2002). have to be modified to better achieve the intended results in final production. 5.9—Acoustic absorption Due to the presence of a large volume of interconnected 6.2—Materials pores of considerable sizes in the material,pervious concrete Pervious concrete is composed of cement or a combination is highly effective in acoustic absorption. The material can of cement and pozzolan, coarse aggregate, and water. be employed as a means to reduce noise generated by tire- Although beyond the scope of Chapter 6,a small amount of pavement interaction on concrete pavements. Noise reduction fine aggregate may be incorporated to increase compressive occurs from a combination of reduced noise generation and strength. The most common gradings of coarse aggregate increased sound absorption. Pervious pavements alter the used in pervious concrete meet the requirements for ASTM j generation of noise by minimizing the air pumping between C33/C33M aggregate sizes of 7(1/2 in.to No.4), 8(3/8 in.to ✓ tire and road surface. In addition, pores absorb sound No.8),67(3/4 in.to No.4),and 89(3/8 in.to No. 16), through internal friction between the moving air mole- Portland cement may conform to ASTM C150/C150M, cules and the pore walls. C1157/C1157M, or any other specification that would Copynght American Concrete Institute Proeded by IHS under 41 with ACI Ucensee.CH2M HIB Wofowide3960456046,User-Troyan.Sean No reproduction or networknp perm red without€tense from IHS Not tot Resale.C1 2&2015 12 09 07 MST PERVIOUS CONCRETE 522R-13 100 2500 40 90 5000 ° C 2000 CL N°9 3 �. E 70 4000 • 30 3 c CA 500 d or d 3000 0 0 }20 m 6 40 1000 3 H 2O00 I i `m 30 3' m i i 10 aCL 20 500 ° 0 10M 1D 10 V I m 0 0 0 0 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 Void content,percent by volume Void content,percent by volume Fig. 6.1—Mininnun void content for percolation on NAA- Fig. 6.2—Relationship between void content and 28-day NRMCA tests and test method, compressive strength for No.67 and No.8 aggregate size. produce an acceptable mixture. A combination of cementi- Table 6.1—Effective b/bo values tious materials that each conform to the appropriate ASTM b/be specifications can be used. Chemical admixtures are ASTM C33/C33M ASTM C33/C33M commonly used to improve various characteristics of Percent fine aggregates Size No.8 Size No.67 pervious concrete. They should meet the appropriate 0 0.99 0.99 ASTM specifications or other specifications that produce 10 0.93 0.93 an acceptable mixture. 20 0.85 0.86 6.3—Water-cementitious material ratio The water-cementitious material ratio (wlcm) is an itself. Some caution should be used when applying these important consideration for obtaining desired strength and quantitative numbers to practical design, as standardized test void structure in pervious concrete.A high w/cm reduces the methods do not yet exist for these properties of pervious adhesion of the paste to the aggregate and causes the paste to concrete;prior discussion should be taken as purely qualitative. flow and fill the voids even when lightly compacted. A low w/cm will prevent good mixing and tend to cause balling in 6.5—Amount of coarse aggregate the mixer,prevent an even distribution of cement paste,and Testing has shown that the dry-rodded density of coarse therefore reduce the ultimate strength and durability of the aggregate, as determined by ASTM C29/C29M, can be concrete. Experience has shown that w/cm in the range of effectively used for proportioning pervious concrete 0.26 to 0.45 will provide the best aggregate coating and paste (Meininger 1988). Those tests have shown that the ratio of stability.The conventional w/cm-versus-compressive strength the dry-rodded volume of coarse aggregate per solid volume relationship for normal concrete does not apply to pervious of coarse aggregate b/bo can be used as a design relationship, concrete. Careful control of aggregate moisture and w/cm is where important to produce consistent pervious concrete. bA, = dry-rodded volume of coarse aggregate in a unit volume of concrete; 6.4—Void content b = solid volume of coarse aggregate in a unit volume To ensure that water will percolate through pervious of concrete;and concrete, the void content, both in design of the mixture and bo = solid volume of coarse aggregate in a unit volume measured as the percent air by ASTM C138/C138M (the of coarse aggregate. gravimetric method)should be 15%or greater,as demonstrated The b/bo value automatically compensates for the effects in Fig.6.1. of different coarse aggregate particle shape, grading, and At a void content lower than 15%,there is no significant specific gravity. Furthermore, the b/bo values for the percolation through the concrete. It is believed that below nominal maximum-size aggregates typically used in 15%voids,there is not sufficient interconnectivity between pervious concrete,3/8 to 3/4 in. (9.5 to 19 mm), are similar, the voids to allow for rapid percolation. Table 6.1 applies the b/b„values for coarse aggregate sizes Figure 6.2 shows that the higher the void content,the higher No. 8 and No. 67 with fine aggregate contents of 0, 10, and the percolation rate, and the lower the compressive strength. 20%of the total aggregate mass. The lower the void content,the lower the percolation rate,and the higher the compressive strength. This figure also shows 6.6—Paste volume,cement, and water contents J the compressive strength increases as the nominal maximum- The proportioning of pervious concrete seeks to establish size aggregate decreases. Compressive strength of pervious the minimum volume of paste necessary to bind the aggregate concrete is also a function of the aggregate strength, paste particles together, while maintaining the necessary void bonding characteristics, and strength of the cement paste structure, strength, and workability. Figure 6.3 can be used Copyright American Concrete Institute Provided by IHS under license with ACI Licensee-CH2M HM Worldwide/5960456046,User-Troyan,Sean No reprcduclion or networking permitted without license from IHS Not for Resale,01l2&2015 12.09.07 MST 522R-14 ACI COMMITTEE REPORT 50 i 6.7-Proportioning procedure E A procedure for producing initial trial batches for pervious 40 concrete is shown in Section 6.7.1.The b/br,method applies a J91I -+om aw. absolute volume concepts. Regardless of how the trial batch 30 is derived,it is essential it be tested for the required fresh and 2 hardened properties before being placed for its intended use. 20 6.7.1 b/bo method-The b/bo method for designing a cpervious concrete mixture can be broken-up into a series of 10 vif.'E Pa tee eight steps: 0 1 1. Determine aggregate weight; 0 2.Adjust to SSD weight; 0 10 20 30 40 50 60 70 3.Determine paste volume; Paste content,percent by volume 4.Determine cementitious content; Fig. 6.3-Relationship benveen paste and void content for 5. Determine water content; No.8 aggregate si_e designations. 6. Determine solid volume; 7.Check void content; and to estimate the volume of the paste for a mixture using 8.Iterative trial batching: normal weight No. 8 aggregates. a.Test for required properties; and Once the paste volume is determined from Fig.6.3,and the b. Adjust mixture proportions until the required perfor- w/cm is selected, the cement and water quantities can be mance is achieved. determined from the following absolute volume relationships: Example-Proportion a well-compacted pervious concrete mixture with a void content of at least 20%. The mixture paste volume Vp=cement volume+water volume should have a w/cm = 0.38. Use a No. 8 coarse aggregate Vp=c/(3.15 x 62.4 lb/ft3)+w/62.4 lb/ft3 having a dry-rodded density (unit weight) of 108.7 lb/ft3, specific gravity of 2.75, and absorption of 1.2%. No fine Substituting w=(w1cnt)c, aggregate will be used in the mixture. Vp=c/(3.15 x 62.4 lb/ft3)+[(w/cvm)c/62.4 lb/ft3] Step 1:Determine aggregate weight „k For No. 8 stone with no fine aggregate, Table 6.1 c can be determined quickly by trial and error on spreadsheet recommends b/bo of 0.99, with dry-rodded density given or algebraically reduced to as 108.7 lb/ft c = [Vp/(0.315+w/cm)] x 62.4 lb/ft3 (6-1) W„= 108.7 lb/ft3 x 0.99 x 27 ft3=2906 lb(dry) In SI units: Step 2: Adjust to SSD weight Given that the percentage absorbance of 1.2% Vp=c/(3.15 x 1000 kg/m3)+w/1000 kg/m3 Wssd=2906 lb x 1.012=2941 lb(SSD) Substituting w=(w/cm)c, Step 3: Determine paste volume Use Fig.6.3 and read along the required percentage voids Vp=c/(3.15 x 1000 kg/m3)+[(w/cm)c/1000 kg/m3] (20% for this example) to the well-compacted curve. Then read down to find the paste percentage at 15%. Fifteen c can be determined quickly by trial and error on spreadsheet percent of a cubic yard is 4.05 ft3.Thus,Vp=4.05 ft3. or algebraically reduced to Step 4:Determine cement content c=[(Vp/(0.315+w/c•m)]x 1000 kg/m3 (6-2) Applying Eq.(6-1), c= [Vp/(0.315+w/cm)] x 62.4 lb/ft3 Therefore,once the paste volume is determined from Fig.6.3, c= [(4.05 lb)/(0.315+0.38)] x 62.4 lb/ft3 and the w/em is selected,the mass of cement can be calculated c=363 lb from Eq. (6-1).From the mass of cement, the water content can be computed. When fine aggregate is used, the paste Step 5: Determine water content volume should be reduced by 2%for each 10%fine aggregate w=c(tv/cm) of the total aggregate for well-compacted pervious concrete, w=363 lb(0.38)= 138 lb and by 1%for each 10%fine aggregate of the total aggregate for lightly compacted pervious concrete. These reductions Step 6: Determine solid volume are necessary to maintain the same percent voids by volume. Aggregate volume V,,=2941/(2.75 x 62.4)= 17.14 ft3 Copyright American Concrete Institute Provided by IHS under license with ACI Ucensee.CH2M Hilt Worldwide/5960458046.User.Tmyan,Sean No reprodualian or netw rkmg per need"hotA license from IHS Not for Resale,012812015 12 09.07 MST PERVIOUS CONCRETE 52213-15 Table 6.2—Typical* ranges of material proportions treatment of pollutants. Some soils may provide adequate in pervious concretet support and drainage so the subbase may be optional. If the support,draining abilities,or filtering abilities are limited by j Proportions,Ib/yd3(kg/m)Cementitious materials 450 to 700(270 to 415) the subgrade, however, then a subbase material should be Aggregate 2000 to 2500(1190 to 1480) used. In areas exposed to freezing-and-thawing cycles, the x/c,n,#by mass 0.27 to 0.34 rock subbase layer acts as insulation and provides a substantial lag in the formation of frost beneath pervious pavement Aggregatexement ratio,#by mass 4 to 4.5:1 (Backstrom 2000;Kevem and Schaefer 2008).The subgrade Fine:coarse aggregate ratio,§by mass 0 to 1:1 also provides vertical support for the paving.Increasing the These proportions are given for information only.Successful mixture design will stiffness of the subbase and subgrade increases the load depend on properties of the particular materials used and should be tested in trial capacity of a given paving system. Stiffness in the subgrade batches to establish proper proportions and determine expected behavior.Concrete P Y g P g Y g producers may have mixture proportions for pervious concrete optimized for perfor- can be measured by the modulus of subgrade reaction, the mance with local materials.In such instances,those proportions are preferable. [Chemical admixtures,particularly retarders and hydration stabilizers,are also used California bearing ratio (CBR), or by a few other less commonly, at dosages recommended by the manufacturer. Use of supplementary common methods. ACI 330R provides typical stiffness cememitious materials,such as fly ash and slag,is common as well. P YP [Higher ratios have been used,but significant reductions in strength and durability values for different types of soils and provides correlations aay result. between the values calculated by the various methods. Addition of fine aggregate will decrease the void content and increase strength. Traditional pavement design attempts to exclude water Cement volume Vc cc 363/(3.15 x 62.4)= 1.84 ft3 from entering the subgrade below the pavement. In most 3 cases,porous paving is designed to encourage water to saturate Water volume Vt,,= 138/62.4=2.21 ft 21 the subgrade below paving. This condition should be taken Total solid volume VS= +Vc 3 V1Y= 17.14+1.84+2.21 into account when determining the properties for the = .19 ft subgrade. The more a soil is compacted, the less porous it becomes. For this reason, pervious paving subgrades are Step 7: Determine percent voids—2Vror 100 usually compacted to a lower density than subgrades for Percent voids=(Vror— traditional concrete paving.The level of compaction is typically Percent voids=(27.00 1.14)/(27.00)x 100=21.52% 90%of Standard Proctor Maximum Dry Density(SPMDD). The modulus of subgrade reaction used in design should Step 8: Check estimated porosity account for this lower level of compaction. ASTM D1883 22% voids, Fig. 6 predicts a percolation rate of defines a laboratory method for determining the CBR of a approximately 7 in./min(178 mm/min). given soil that includes an option for soaking the soil sample in water for 96 hours before testing. This option should be Step 9: Iterative trial hatching and testing used for testing fine-grained soils that would be compacted The trial batch weights per cubic ft are as follows: to the aforementioned 90%of the SPMDD or the compaction Cement=362 lb criteria established by the architect-engineer. Water cc 138 lb When specifying compaction for structural design, No. 8 aggregate=2941 lb(SSD) consideration should be given to the effect compaction has Total weight=3441 lb on the hydraulic properties of different soils. Compacting Density=3441/27= 127.4 lb/ft3 some clay soils to 90% may cause a large reduction in permeability whereas compacting sandy soils to nearly 6.8—Typical ranges of materials 100% may not have any affect. It is important,therefore, to PerviousConcrete.org (http://www.perviouspavement.org/ carefully examine the soils present on each project for both mixture%20proportioning.htm), a joint effort of National structural and drainage capacities before specifying a Ready Mixed Concrete Association(NRMCA)and the Port- compaction range.Equally important is required field testing land Cement Association (PCA),has published Table 6.2. of the subgrade and subbase for permeability after compaction CHAPTER 7—PERVIOUS PAVEMENT DESIGN to confirm they still conform to both structural and hydraulic 7.1—introduction calculations used for the site. In the thickness determination of a pervious pavement Expansive soils are soils that change volume when subject section,two important analyses should be conducted:one for to changes in moisture content. Expansive soils can be structural adequacy and one for hydraulic characteristics. mitigated by chemical treatment or by removing their upper These two characteristics influence each other so they both layers and replacing them with non-expansive soil. The should be addressed with care. This chapter discusses the depth of soil replacement or soil treatment should be selected aspects applicable to the structural design. so the downward soil pressure provided by the shallow stable soil exceeds the expansive soil pressures generated by ` 7.2—Structural design increases in the moisture content of the deeper soil. With 7.2.1 Subgrade and subbase—The subbase is the aggregate lime stabilization,the permeability of a clayey soil is increased layer installed below the paving. The subgrade is the soil rapidly.Soils with higher clay contents and those compacted below the paving and the subbase. The subbase provides on the dry side of optimum tend to show greater increases in vertical support, storage capacity, and filtering ability for permeability with lime treatment. Some permeability, Copyright American Concrete Institute Provided by IHS under license wdh ACI llcensee.CH2M Hill Worldwider5960456046,User.Troyan,Sean No reproduction or networking permired without license from IHS Not for Resale,01 26r2015 12:09.07 MST 522R-16 ACI COMMITTEE REPORT however, will decrease with age (Bell 1993). Soils treated areas within a given city's limits, the regulations have been with cement and fly ash show reduced permeability after known to change.The basics of the technology are the same, application(Little et al.2000). Depending on the application, however,regardless of geographic area. reduced permeability might be desirable for applications Attempts have been made to reduce the impact of urbanization such as water harvesting. by reducing stormwater runoff volumes to predevelopment Some soils are subject to frost heaving.Soils located above levels and treating stormwater before it leaves the site.In the the frost depth should be removed and replaced by soils that are U.S., the National Pollution Discharge Elimination System not subject to frost heave. As indicted previously, an (NPDES)requires treatment of all stormwater to reduce the appropriate subbase has proven to be effective at protecting pollutant levels of the water.This is an empirical science,not porous pavements from frost heaving. nearly as exact as treatment of drinking water supplies due to Adding a granular aggregate subbase below the concrete the variability of the pollutant loads and flows.The technology paving increases the stiffness of the pavement support. ACI is not intended to purify water to a distilled type condition 330R,Table 3.2, indicates the increase in subgrade modulus because it is not practical, economical, or necessary. The provided by different thicknesses of subbase. This granular intent is only to remove as much pollutant load as possible in subbase can also be used as a reservoir for storing stormwater. an attempt to discharge cleaner water at sustainable rates,and 7.2.2 Concrete strength—Guidance for structural design reduce the impact of urbanization on water supplies. of conventional concrete pavements is provided in ACI Water supplies typically fall into two categories: surface 330R for parking lots and in ACI 325.12R for streets and water and groundwater. Site development on sandy soils with roads. These documents cover many different aspects of deep groundwater deposits may follow a design philosophy of paving design. The structural design recommendations in infiltration: discharging water to the groundwater table as these documents,however,are not necessarily applicable for cleanly as possible with discharge to surface water bodies use with pervious pavement. As there are no standardized only in heavy storm events, When site development is on test methods for strength of pervious concrete, design and clayey or silty soils,or in regions of shallow bedrock,the site specification by concrete strength should be avoided. drainage should typically treat the water before running off 7.2.3 Structural thickness selection--Sufficient perfor- site to merge with a surface water body such as a stream, mance data that offer a general standard pavement design for river, or lake. On these low-permeability soils, however, use in prolonged exposure to heavy truck traffic is unavailable. some water infiltrates during every storm,just as it does in Success of existing pavements by installers around the high-permeability soils;only the amount is less.The cumulative effect on recharge and water-quality country varies by experience, pavement and mixtureq Y treatment over the designs,and local conditions. course of a year can be considerable. Traffic categories are defined by average daily truck 7.3.1.1 There are three specific design features of traffic(ADTT).ACI 330R provides a full discussion of this pervious concrete that the designer may benefit from: topic.The ADTI'does not correspond to a single-sized truck reduced runoff volume, reduced treatment volume, and axle load.It assumes a collection of truck sizes from small to reduced impervious area on the site. large, with a high frequency of small trucks and a low 7.3.1.1.1 Reduced runoff volume—Reduced runoff frequency of large trucks. Because the heaviest trucks,even volume is the amount of stormwater that a piece of developed in small numbers,dominate the fatigue damage of pavement, property would discharge to an adjacent land or water body they should be the basis for traffic category selection. if stormwater BMPs were not in place;this is in excess of the Pavement designs with demonstrated performance history predevelopment discharge volume. Such BMPs include are available from experienced installers and being used retention ponds, detention ponds, underdrains, swales, and currently in several areas of the U.S.Care should be taken to wetlands.Most of these BMPs consume valuable,developable verify the installer has a history of successful performance real estate. By eliminating or reducing the size of these both from installation quality and use of designs similar to facilities,a project can be more profitable to the owner.This any specific project needs. If unable to find suitable local may reduce the amount of real estate necessary or increase installers with examples of successful projects,the National the amount of rentable space. Ready Mixed Concrete Association (NRMCA) (2007) 7.3.1.1.2 Reduced treatment volume—Reduced suggests pervious pavement sections of 6 in. (150 mm) of treatment volume is the quantity of stormwater that should pervious concrete pavement for low (under 5) ADTT truck be held on site and treated before leaving the property.Treatment exposure in parking lots.This is based on historical success in may occur through a combination of chemical,physical,and the U.S.There are no current standard thicknesses for streets but biological processes depending on the BMP type. there are examples of low-volume streets being installed with 7.3.1.1.3 Reduced impervious area—Reduced pavements ranging from 6 to 12 in.(150 to 300 mm)thick. impervious area is the fraction of the land area that does not allow infiltration of rainfall at the start of a rainfall event;this 7.3—Stormwater management design usually consists of building, sidewalk, and pavement areas. 7.3.1 General—The major benefit of pervious concrete is Many municipalities limit the amount of impervious area its hydrological properties. From one state to another, local allowed on a given project site. regulations determine how much of this benefit the designer 7.3.1.2 For a more thorough discussion of stormwater is able to capitalize on. Even within different geological treatment BMPs, the reader is encouraged to review the Copyright American Concrete Institute Provided by IHS under license with ACI Uceneee—CHW HAI Werldwider5960456046.User.Troyan.Sean No reproduction or networking permitted without license from IHS Not for Resale,01262015 12,09.07 MST PERVIOUS CONCRETE 522R-17 information at the EPA's Web site (http:// www.epa.gov/ Table 7.1—Pollutant removal of porous pavement waterscience/stormwater). More information on local (Winer 2000) * , regulations can be found in the reader's regional stormwater Pollutant Pollutant removal, management manual, such as the St. Johns River Water TSS 95 Management District's (SJRWMD) Applicant's Handbooks: TP 65 Regulation of Stormwater Management Systems(1999).For TN 82 general information on stormwater hydrology not linked to NOx NA specific jurisdictions,review any of the stormwater textbooks, Metals 98 to 99 such as Ferguson's Stormwater Infiltration(1994),Ferguson's Bacteria NA Introduction to Stormwater: Concept, Purpose, Design (1998), and Debo and Reese's Municipal Stormwater Data based on fewer than five data points. Management(2002). The use of pervious concrete pavements as a retention or infiltration system BMP is effective for improving runoff posted on the site that identifies pervious concrete pavement water quality and reducing runoff volume when properly areas.Such signs should direct maintenance crews to the local maintained(Table 7.1).The SJRWMD,for example,defines h1PDES enforcement authority and might read, "Pervious retention to include"pervious pavement with subgrade."The concrete pavement are used on this site to reduce pollution. EPA defines pervious concrete as an infiltration system. Heavy vehicles prohibited.Do not resurface with nonpervious Pervious concrete pavements can be designed to accommodate material.Call XXX-XXX-XXXX for more information," not only the rain falling on its surface, but also to capture a Designers can account for the clogging potential of a good portion of excess runoff from adjacent areas. To pervious concrete pavement in their drainage design.If a site prevent premature clogging from runoff,the use of a sediment is designed for a government facility, such as a stormwater trap or other sediment separation system may be necessary. utility with an existing maintenance program and staff,clogging Also, calculate the increased water storage capacity require- would not be considered. In private development where ments to hold the added storage load from the additional areas. maintenance may not be performed, the designer may add a Reduction in drainage facilities from reduced runoff factor of safety to the stonnwater design to account for the volumes using pervious concrete has an economic benefit to anticipated level of clogging and accompanying reduction in the developer. This economic benefit can be evaluated by the porosity of the pervious concrete pavement.Some specific comparing the price of building a pervious concrete parking case studies of field performance and clogging are provided in lot to building a pond with drainage structures and buying reports by Wanielista et al. (2005) and Delatte et al. (2007). the associated land. The designer of a pervious concrete pavement can reduce 7.3.2 Pervious pavement maintenance—In the past, clogging potential by ensuring that the design of the site: maintenance had been a regulatory concern that prevented Shows landscaped areas at lower elevations than the wide acceptance of pervious concrete, A pervious concrete pervious concrete pavement (Fig. 7.1), reduces to a pavement today will still maintain permeability even when minimum the slope of the landscaped areas when lower clogged. Clogged pores or subgrade prevent stormwater elevations are not possible, and includes a curb to from percolating through the concrete at high rates(Wanielista isolate landscaped areas that are at higher elevations et al. 2007; Mata and Leming 2008).Thus, if stormwater is than the pavement; unable to drain through the pervious concrete layer at the Minimizes soil erosion of disturbed areas. Bare soil in design rate, it is no longer sufficiently pervious, the design these areas should be avoided and the use of permanent benefit assumptions no longer valid, and the pavement has pasture and brush cover is recommended. Special failed, Pervious concrete pavements can perform well for control measures, such as silt fences, should be used at years with some level of clogging (Wanielista et al. 2007), all times during construction; but the rate should be above the design rate. For a pervious Prevents vehicles from driving from unpaved areas pavement system to perform well, it may need to be main- onto the pervious concrete pavement; tained at some regular interval. If a pavement is in a harsh environment,such as a coastal area,or anywhere that would Does not lay in the path of wind from nearby unpaved cause heavy accumulations of fines, it may be necessary to or beachfront areas; and perform this preventative maintenance more frequently. A Limits the amount of stormwater flowing onto the qualified professional such as a licensed professional pervious concrete from adjacent, conventional (not engineer or landscape architect should inspect the pavement to pervious)pavements and landscaped areas unless it can determine an appropriate maintenance schedule, if it is be shown that: functioning properly,or if cleaning is necessary. ° The volume of water from the conventional pavement One nonstructural component that can help ensure proper will be free of sediments; maintenance of pervious concrete pavement is a carefully ° The pervious subbase has been designed to handle worded maintenance agreement that provides specific the water from the combined areas; and guidance,including how to conduct routine maintenance and Sufficient pervious concrete surface area is available surface repairs or rehabilitations. Signs should ideally be to catch leaves, litter, or other debris that may Copyright Ame,kar Concrete Instltute ?resided by IHS under Hcense with ACI Ucensee.CH2M Hill Worldwide/5960456046,User.Troyan,Sear No reproduction of networking permitted without license from IHS Not for Resale,0128/2015 12 09.07 MST 522R.18 ACI COMMITTEE REPORT Void Pct. "w t `1'11F 4k 1k' J K '.sue§" . 100% i � �} t2''A'ri v>°" ^..4 .,�'�"+i#^i.��.-.5 • , v: .a - p$ O- s°� oC o ' � o Perimeter u' c7 vet ..0 60 rn a o P C•a a o P' C p d 18% ' o Pervious P av t�p Cure an� I.r���,n�,olea°� �,} Limestone i ;ef�'iyt= P .� Sub¢ase 4 30% ..... subgrade '26„ 15% 2.5' Fig. 7.1—Example of landscaped area at lower elevations than pervious concrete pavement. V_ i Seasonal prematurely clog the pervious concrete between High Water maintenance periods. 7.3.3 Drainage design—Runoff is estimated through the Fig. 7.2�Schemotic of pervious concrete pavement designed as storntivater retention,system(I in. =25.4 rnm). use of many accepted methods. Two of the more common tools are the rational method and the Soil Conservation Service (SCS) curve number, With either method the standards.In other parts of the U.S.,for other soil types,the designer should consider in the runoff analysis a variety of compaction practices are different. Glacial tills have been input and output variables such as absorption, evaporation, compacted to 90 to 95% of the standard Proctor; in the rainfall intensity,infiltration,and duration of the storm.Each Carolinas, compaction has been to 92% of the modified of these variables will have an impact on the runoff volume Proctor; and in Georgia, fine-grained soils are commonly and the treatment volume necessary for the site. compacted to 95%of the standard Proctor. In this situation, The rational method uses a coefficient to determine the it may be necessary to add an open-graded aggregate peak runoff rate for a given rainfall intensity and drainage subbase (or recharge bed) to the pavement system to area. The runoff coefficient C accounts for land use, soil compensate for the softness of subgrade soil—with the type,and slope of the area.Typical values for C range from benefit of added retention volume. 0.05 for a flat lawn on a sandy soil to 0.95 for a rooftop. With the SCS method (Soil Conservation Service 1986), Other types of pervious pavements have been assigned soils are classified into hydrologic soil groups (HSGs) to rational coefficients ranging from 0.65 to 0.95.For a pervious indicate the minimum rate of infiltration obtained for bare pavement,the underlying soil type and its permeability will soil after prolonged wetting.The HSGs—A, B, C,and D— have an impact on the runoff coefficient.A well-maintained are one element used in determining runoff curve numbers.A- pervious pavement will typically drain faster than the type soils have the highest permeability, with each letter subgrade soils,which limit the infiltration rate of the system. designation having lower permeability in B,C, and D soils. Some current research(Wimberley et al.2001)indicates that This soil designation,in combination with the land use,will for certain pervious concrete system designs, particularly identify a curve number(CNN .The CN value tells the designer those over well-drained subgrades and subbases, the which curve to reference to determine the runoff volume for a runoff coefficient for pervious concrete is negligible for 2- given storm event.This method is more commonly used for to 5-year storms, and as low as 0.35 for 100-year storms. generating a full hydrograph rather than just estimating peak Other studies (Haselbach 2006) also indicate that there will flows.Pervious concrete pavements have been assigned CNs be reduced infiltration for systems overlain with sandy soils ranging from 60 to 95. Once again, the subgrade soil type but that the expected runoff coefficients will still be very low and degree of compaction have an impact on the CN and, for most storms. thus,on the drainage properties of the system. Research shows that as soil density increases, the rate of When designing a pervious pavement system, such as a infiltration, and thus the permeability of the soil, decreases retention or an infiltration system, the volume of both the significantly(Das 1993).A decrease in the permeability of a pavement and subbase should be considered (Paine 1990). soil would therefore justify an increase in the rational For example, consider a section of pervious concrete with coefficient for a given design. Subgrade soils for a pervious 20%effective void space.In a 6 in. (150 mm)thick pavement concrete pavement should, therefore, be compacted section, this void space is sufficient to hold more than 1 in. uniformly and sufficiently to provide proper pavement support, (25 mm) of stormwater. Additionally, if the pervious but not overcompacted so as to reduce the permeability of the concrete is placed on a 6 in. (150 mm) section of a crushed soils and increase the rational coefficient.The Florida Concrete stone subbase, the total capacity of the system increases to and Products Association (FCPA) (1990) recommends approximately 2-1/2 in.(65 mm).The minimum thickness of compacting sandy subgrade soils to a minimum density of the pervious concrete pavement will be determined by the 92 to 96% of maximum dry density per AASHTO T-180 structural needs of the pavement system. It may be necessary, Copyright American Conaele Institute Provided by IHS under ecense with ACI Lkens"-CH2M Hill Worldwide/5960458046,User.Troyan,Sean No reproduction or networking permitted without license Irom IHS Not for Resale.01128i2015 t 2:09,07 MST PERVIOUS CONCRETE 522R-19 however, to build a thicker pervious concrete layer or 7.3.4 Pervious area credit—Many municipalities encourage subbase layer to increase stormwater storage capacity, but green space and a reduction of runoff in development through this may not be the most economical solution. If further restrictions on the amount of impervious area on the project capacity is necessary, storage may be above the pavement site.Typically, impervious area is limited to 25 to 75%of a surface in a curbed parking area(Fig.7.2). developed piece of property.Due to the nature of a pervious Other ways pervious pavements have been designed to concrete pavement, it should not be considered impervious. treat stormwater include the use of an underdrain system.In With concerns over green space, however, it is rarely this method,groundwater recharge may be limited due to site counted as pervious area.It is common,however,for munic- soil conditions. The pervious pavement is placed over a ipalities to assign a pervious area credit for pervious perforated pipe that is laid in a bed surrounded by an open- concrete.Different municipalities have used values of 25%, graded aggregate.Stormwater infiltrates through the pavement, 50%, and 100%, which to the owner means a reduction in through the gravel,and finds its way into the pipe.From there, required grassy or undeveloped area on the project site and the treated stormwater is discharged into a receiving water an increase in the area that can be developed. body. Treatment efficiencies for this system average 66%. As an example, consider a project site that is 1 acre Additionally,there will be some direct recharge of the ground- (43,560 ft2 (4046 m2]), with 10,000 ft2 (930 m2) of a water that will reduce the total runoff by as much as 33%. pervious concrete parking lot. If the local municipality (Florida Department of Environmental Protection[FDEP]). requires a 30%pervious area on the project site,then the site Further groundwater recharge systems may include the use design would be limited to having 30,500 ft2 (2800 m2) of of drilled shafts backfilled with an open-graded aggregate, impervious area. This includes the building, sidewalks, and passing through clayey soils to more permeable strata. A parking areas,and assumes no credit is given for the pervious typical design for this system might include a layer of an concrete. With a 50% pervious area credit for the concrete open-graded aggregate subbase for the pervious concrete parking lot, the developable area would be expanded to pavement laying on the fine-grained site soils. The shafts 35,500 ft2 (3300 m2)—a 16% increase in the amount of would be spaced regularly to provide sufficient recharge usable land on the site. This can make a project much more capacity. The subgrade would have to be sloped to provide appealing to a developer,and with a reduction in undeveloped positive drainage to the shafts. Treatment efficiencies for land,there can be a similar reduction in urban sprawl,as smaller this system would be expected to be similar to the underdrain sites could be used to fulfill specific development needs. design. Recharge rates, however, would be expected to be Local agencies are faced with the ever-growing regulations much higher. requiring stormwater treatment. It may be in their best Several other designs have been used to pass excess water- interest to increase the percentage of credit given to pervious quality volume,increase storage capacity,or increase treatment parking areas to the actual percent of runoff retained on-site volume.These include: to encourage more people to use the technology. Pervious • Placing a perforated pipe at the top of a crushed stone concrete allows the city to grow with much less stress on reservoir to pass excess flow after the reservoir is filled; storm drainage infrastructure. Because pervious concrete • Providing surface detention storage in a parking lot, pavement allows water to flow back into dwindling aquifers, adjacent Swale, or detention pond with suitable overflow it offers a very rare opportunity to change stormwater from a conveyance; liability into an asset. • Adding a sand layer and perforated pipe beneath a 7.3.5 Design example—Given: recharge bed for filtration of the water-quality volume; The pavement should store the first 1/2 in. (13 min) of and untreated runoff and recover that volume within a 72- • Placing an underground detention tank or vault system hour time period following a storm. beneath the layers to store the treated water for reuse. The storage volume V,required in the pervious pavement Evaporation is another important factor in the calculation of may be calculated as water storage.Research shows that water stored in the pervious pavement and subbase may evaporate(Wanielista et al.2007). V,=rainfall(in.) x A (acre)x 43,560(ft2/acre) All of the intricacies of a stormwater drainage design x 1 (ft)/12(in.) (ft3) (7-1) using pervious concrete pavement will be strongly tied to local practices and regulations. Refer to Section 7.3.5 for a sample set of design calculations that has been published by �', =rainfall(min)x A x 1 (m)/1000(min) (m3) the FCPA (1990). Always review the full text and local stormwater regulations. for a 1/2 in.(13 mm)first flush,then In addition to runoff, the designer should approximate pollution loads, including their nature and approximate V,.= 1/2(in.)x A x 43,560(ft2/acre)x 1 (ft)/12(in.) range of concentration. This information, combined with = 1815A (ft3) the necessary hydrograph,will allow the designer to deter- mine the appropriate size and design of the stormwater management system, V,.= 13 (mm)x A x 1 (m)/1000(mm)=0.013A (m3) Copyright American Concrete Institute Provided by IHS under license with AC Ucensee-CH2M HIM Worldwidw5960458046,User-Troyan,Sean No reproduction or netwoming permitted without license from IHS Not for Resale,01:28/201512:09.07 MST 522R-20 ACI COMMITTEE REPORT where V,=volume of storage required,ft3(m3);and A=size the pavement. Because the strength of the pavement is of the facility plus any contributing area,acre(in2). increased with increased density,the design of the concrete The Florida Concrete Products Association(1990)suggests section should consider this reduced strength at the base of that the storage capacity of a pervious pavement system on the paving.At a concrete plant in Oregon,four 10 in.(250 mm) Y sandy subgrade soils should include the void space of the soil porous pavements were cut into beams to measure the above the seasonal high groundwater table and any storage difference in flexural strength between the compacted top of the pervious concrete pavement.This storage volume may and bottom half of the pavement. The results showed that be calculated as follows while the top flexural strengths varied from 310 to 485 psi (2.14 to 3.34 MPa). The bottom portion of the test panels, Vp=A x dt x p 1/100 (7-2) below the effect of the compaction,had a consistent flexural strength of 272 to 275 psi(1.88 to 1.90 MPa). While this is a Vs=A x d,x p2/100 (7-3) very limited test, it does show the noncompacted area of the pavement was consistent and that significant strength gain 3 3 can be achieved by using compaction(Erickson 2006). where Vp = available storage in pavement, ft (m ); VS = available storage in subgrade,ft3(m3);A=area of the pave- The void structure of a pervious concrete mixture not only ment,acre(m2);dt =thickness of the pavement,ft(m);d2-_ allows for the vertical transmission of water,but it will also thickness of the subgrade, ft (m); pit — percentage of void allow horizontal flow.This unique ability should be considered space in the pavement (%); and Pz = percentage of void in establishing the drainage profiles.The vertical rate of flow space in the subgrade(%). is dependent on the permeability of the subgrade and on the Upon completion of calculating the required water-quality thickness and void ratio of the pavement. To the greatest storage volume V,and deducting the subgrade soil volume V, extent possible, parking area profiles should be graded and available pavement storage volume Vp,the net difference without slope. This will allow increased time for the will either be negative,indicating the requirements are met,or subgrade to absorb and transmit water to the lower strata and positive, indicating that additional storage is necessary. A reduce the horizontal flow rate. Where conditions do not granular subbase, such as an ASTM No. 57 material with a allow for flat grades, the designer may consider providing void space of 30% or greater, could provide additional impervious barriers transverse to the direction of horizontal storage.The area above the pavement is available for storage flow. These barriers can be installed by increasing the as well. The designer is cautioned that when applying this consolidation of the pavement strip along the edge of trans- verse construction joints.The increased consolidation closes { design technique,however,the water height for the infrequent c f the void structure at this location.Installing transverse strips design stone may cause the water to rise above the pavement surface.The pavement elevation should be lower than adjacent of normal impervious concrete reduces lateral flow in the building floor elevations to avoid flood damage. down-grade direction. Curbs around the perimeter of the The FCPA guide(1990)gives further design examples for paved area also assist in reducing lateral flow rates, as well calculating the retention capacity of a parking area, runoff as meeting the stormwater retention requirements. Subbase quantity, and recovery time. Some of these calculations are erosion and damage to the pavement can occur if insufficient also given as examples in the Atlanta Regional Commission's steps are taken to control the volume and velocity of the (ARC'S)Georgia Stormwater Management Manual(2001). water flowing through the subbase and subgrade.Edge curbs Designers may want to consider adding redundant or other structures to prevent this erosion should be drainage if the elevation of the finished paving surface is constructed along all areas where the potential exists for close to any areas that would be significantly impacted by Water to flow under the pavement. occasional inundation. This can be as simple as grading the pavement to gently slope away from a building. CHAPTER 8—PERVIOUS PAVEMENT CONSTRUCTION 7.4---Other considerations Construction of pervious concrete pavements should The properties of in-place pervious pavement are highly comply with project plans and specifications to provide a variable and subject to the skill and experience of the finished product that will meet the owner's needs and local installation contractor and the concrete supplier. The regulations.A sample specification is available from ACI concrete properties used for design should be calibrated to 522.1. Construction starts with thorough planning. A local experience whenever practical,but due to the specialized preconstruction conference and/or construction of test nature of the product and the need for qualified installers it sections are recommended to address issues such as: may be advantageous to seek regional installers until qualified Confirming that all project personnel are working from local installers become proficient with the product. the latest set of plans and specifications,and all revisions Pervious pavement is usually placed, then screeded and are documented; compacted. As pavement thickness is increased beyond 8 or Verifying that all required documents and submittals 10 in. (200 or 250 mm), it becomes difficult to compact the have been completed; full cross section of the pavement with uniform results due Determining the construction sequence and joint spacing; to a limited depth of influence of the roller. The top of the Arranging the staging area for equipment,material,job- pavement will become-more-compacted compacted than the bottom of site trailers,personnel needs,and safety requirements; Copyright American Concrete Institute Prawded by IHS under license with ACI Ucensee-CH210 Hill Worldwlde,5960456046,User-Troyan Sean No reproduction or nedvorifing permitted without license from IHS Not for Flesale,0V281201 5 1 2:09.07 MST PERVIOUS CONCRETE 522R-21 is Arranging adequate access for concrete delivery trucks layer of rock and prepared subgrade. Fabric allows water to and concrete conveying systems; pass through,but keeps the soil in the subgrade from eroding • Selecting the optimum equipment for project size and or migrating into the voids of the subbase layer. anticipated conditions; Well-prepared,uniformly compacted subgrade and subbase • Coordinating on-site inspections,and/or materials testing; at the correct elevations are essential to the construction of is Verifying the proposed mixture design, material and quality pavement. The subgrade and subbase should not be admixture availability, and proposed delivery schedule muddy,saturated,or frozen when placement begins.In addition, with the concrete supplier; and the subgrade and subbase should be moistened before • Verifying that the pervious concrete contractor, concrete placement begins.Failure to provide a moist support concrete plant personnel, and testing personnel layer may result in a reduction in pavement strength and could (Section 9.3)are adequately qualified. lead to premature pavement failure.To provide a level surface for pavement construction, wheel ruts should be raked and 8.1—General construction principles recompacted before concrete placement begins. The characteristics of pervious concrete dictate a construction process notably different from that for normal cast-in-place 8.3—Placing concrete (Offenberg 2005a). The process is depositing, A well-planned project layout can expedite construction screeding,compacting,and following immediately with sheet operations, permit efficient use of placement equipment,and membrane curing. Equipment that has been used success- provide access for concrete delivery trucks. The contractor fully to place pervious concrete includes low-frequency and designer should agree on joint layout and construction vibrating truss screeds in combination with heavy pipe rollers, methods before construction begins. A drawing showing the both single- and double-tube counter rotating tube screeds, location of all joints and the placement sequence should be plate compactors, slipforms, laser screeds, and machines available before construction begins. Locations of fixed specifically made for placing pervious concrete. Normal objects should be established with the joint pattern and concrete finishing procedures are not employed, construction methods in mind. No matter what equipment is used, a pervious pavement Pervious concrete placement should be completed as cannot be successfully constructed unless the concrete quickly as possible. Pervious concrete has almost no excess placed has the correct consistency.If too dry,a concrete creates water in the mixture. Fresh material exposed to the elements issues with cohesiveness and cement hydration efficiency, for a significant time period will lose water needed for hydration while too wet a mixture results in the paste phase draining as well as retention of the cohesiveness of the mixture. This down, leaving a weak structure and possibly clogging the drying of cement paste can lead to loss of strength and future pavement bottom. Admixtures such as hydration stabilizers, raveling of the pavement surface. All placement operations viscosity modifiers, and water reducers are helpful in and equipment should be designed and selected with this in producing and maintaining the proper consistency of pervious mind, and scheduled for rapid placement and immediate concrete.The low water content and porous structure,which curing of the pavement. exposes paste surfaces to evaporation,requires that delivery 8.3.1 Forms--Typical pervious pavement construction and placement be completed rapidly so that sheet membrane requires the use of edge forms, as is typical for cast-in-place curing can be in place within 20 minutes of concrete placement, slab-on-ground construction. Forms may be made of wood, although this time may be significantly reduced depending plastic,or steel and should be as thick as the pavement.Forms on environmental conditions. The porous structure also should be of sufficient strength and stability to support makes pervious concrete more sensitive to low temperatures equipment used for screeding and compacting during during and after placement,thus dictating heightened attention placement. The subgrade and subbase material under the to cold weather concreting practice. forms should be compacted in accordance with the designer's recommendations. The length of the form-pins should be 8.2—Su bg rade/sub base preparation selected based on the type of subgrade or subbase material. The subgrade is the bed on which the pavement structure Enough form-pins or stakes should be used to resist movement is constructed and can be either native materials or imported and bending.All forms should be cleaned and coated with the fill. In some cases,pavement will be placed on a subbase of appropriate release agent as necessary. clean gravel or crushed stone,which may be used as a storm- 8.3.2 Depositing concrete—Concrete should be deposited water storage basin. If the compacted site soils or imported as close to its final position as practical. This is commonly fill have sufficient percolation rates and the project is not in done by direct discharge from the chute of the mixer truck an area where freezing and thawing is a concern,then a base directly onto the subgrade or subbase (Fig. 8.1). Generally of gravel may not be required. The project engineer should only one section of chute can be added to the chute section make this determination based on local regulations, soil mounted on the mixer truck.This limits the width of placement { permeability, stormwater volume, anticipated traffic loads, lanes to 15 ft (4.5 m). For placements that mixers cannot and pavement purpose, reach, or where the soil disturbance is to be minimized, a When the subgrade soil properties require that a rock base conveyor may be used (Fig. 8.2). After the concrete is be placed below the pavement as a stormwater storage basin, deposited, it should be cut to a rough elevation with a nonwoven, geotextile fabric should be placed between the concrete rake or similar hand tool(Fig. 8.3). Care should be Copyright American Concrete institute Provided by IHS under license wlh ACI Licensee-CH2M Hio Worldwke6960458046,User-Troyar,Sean No reproduction or neworkng permitted without license from IHS Not for Resale,01,28,2015 12:09.07 MST 522R-22 ACI COMMITTEE REPORT 4,:s Fig.8.4--Example of riser strip in place. 3w Fig,8.1 Placement of pervious concrete by rear-discharge mixer truck. eoNE .loco .L Fig. 8.5—Use of vibratory screed for strikeoff of pervious concrete. Fig.8.2---Use of conveyor to place pervious concrete. aggregate used in the pervious concrete, and the contractor's l placement methods.Refer to Section 8.4 for more details. 8.3.4 Placing equipment—Placement methods vary depending on the project size.For small jobs such as driveways, or for tight areas,a hand-held straightedge or vibrating screed is acceptable. For larger jobs, an A-frame, tow-frequency, vibrating screed may be used(Fig.8.5).It is important to strike .r;,; ,,� off the concrete as quickly as possible.Handwork for larger placements, therefore, is not recommended due to its lack of speed. Weighted spinning-tube screeds followed by cross _ rolling have been used successfully to place and compact the "'r" pavement in one step,eliminating some need for riser strips. Fig.8.3-Raking pervious concrete to rough elevation. When using this process, the mixture should be properly proportioned and the concrete placed at a relatively fluid consistency to achieve adequate compaction. There have been limited projects where laser screeds and taken to minimize filling voids in the concrete by overvibration concrete slipform equipment have been used for placing or walking in the plastic concrete and contaminating the large volumes of pervious concrete in pavements. This pervious concrete with deleterious material. process requires specialized expertise and experience in 8.3.3 Riser strips—Pervious concrete is compacted into its mixture proportioning and placement techniques.The key is final position, therefore, riser strips may be placed on top of that whichever method of compaction and finishing used, the forms to provide an initial strikeoff elevation (Fig. 8.4). proper mixture consistency should be verified for the These strips vary from 3/8 to 3/4 in. (9 to 19 mm)thickness; selected method. the necessary thickness will be dependent on the required 8.3.5 Miscellaneous tools—Traditional concrete finishing surface compaction, thickness of the pavement section, the tools such as edgers and come-alongs (a tool that looks like Copyright American Concrete Institute Provided by IHS under license with ACI Licensee-CH2M Hill Worldwdel5960456046,U—Troyan Sean No reproduction or not—hing permined wnhoul Icense from IHS Not for Resale.01 2812015 12 09.07 MST PERVIOUS CONCRETE 522R-23 `I t � r Fig.8."esult of riser strip use after removal. I Fig. 8.7—Example of compaction of pervious concrete by a hoe and has a long straight-edged blade) may be used to rolling. facilitate proper placement of pervious concrete. Bull floats and traditional concrete trowels should not be used. r' 8.3.6 Using pavement as a form--Special care should be � . taken when placing a pervious concrete section next to an earlier placement from the previous day. (Same-day,side-by- ro } side placements, using mechanical equipment is not recom- mended).The following is the recommended procedure: ' . . 1.Carefully peel back the curing sheet covering the earlier �� -���; 3,,,, placement to reveal just the edge of the pavement. Care should be taken to keep as much of the previous placementJ,. r � ° covered as possible. Misting of the uncovered areas is � " recommended; 2. Place a riser-strip or protective sheet on top of the Fig. 8.8—Example of small roller used for compacting finished placement and along the edge; small paved area. 3. Place fresh pervious concrete up to the edge of the existing pavement; Extra compaction may be necessary in some areas such as 4. Strikeoff the freshly placed pervious concrete to the tight turn-radiuses of the parking lot pavements. Because proper elevation and compact edges, being careful not to these areas may receive more wear from increased stresses as impact the existing placement; a result of the turning motion of passing vehicles, it is 5. Continue with roller-finish as usual, lineup joints with recommended these areas receive a greater surface compaction, previous placement; and even at the loss of some surface permeability, by using a 6.Re-cover the existing placement and the new placement thicker riser-strip in the radius areas with curing-sheeting. Some situations require extra effort to ensure a quality pavement. Where ride quality is of special concern, as in 8.4—Consolidation drive-lanes,the pavement may be cross-rolled to smooth out When using riser-strips, they should be removed from vertical deviations (Fig. 8.9). Adjacent to sidewalks and at each form immediately after strikeoff (Fig. 8.6) and the exposed pavement edges, the concrete may be tooled to concrete be compacted to the elevation of the form with a provide a smoother and tighter corner (Fig. 8.10). This weighted roller(Fig. 8.7). A hand-tamp may be used along operation performed at the wrong time could result in the edges to facilitate compaction along the forms.The roller cracking of the matrix and thus increased raveling. Great compacts the near-surface aggregates,resulting in a stronger care should be taken when performing this operation. After bond between the surface aggregates but decreasing the strikeoff, compaction, and edging, no other finishing permeability of the surface.The construction process should operations should be performed. result in both adequate strength and permeability.The roller should span from form to form and be heavy enough to 8,5--Jointing obtain the necessary compaction. The average roller of the Contraction joints,sometimes referred to as control joints, size needed to span a 12 ft (3.7 m) lane width weighs should be installed as indicated by the plans. They should approximately 500 lb(227 kg). A custom-built rolling tool have a depth of 1/3 to 1/4 of the thickness of the pavement. (Fig.8.8)can be used in tight areas and for smaller placements. Although it is highly recommended that joints be installed in The roller in Fig. 8.8 weighs approximately 70 lb(32 kg).To the fresh concrete with special tools,saw cutting joints after decrease the chance of leaving roller-marks in the surface of the the concrete hardens can also be performed. Shrinkage cracks pavement,small rollers should have machined beveled-edges. will occur in pervious concrete as well as in conventional Copyright American Concrete Inetltute Provided by IHS under license with ACI Licensee=CH2M Hill Worldwide/5960459049,User-Troyan,Sean No reproduction or networking pemiided without license from IHS Not for Resale.0128/2015 12.a9:07 PAST 522R-24 ACI COMMITTEE REPORT t- �.t t tir a Fig.8.12—Example of jointing tool built into primary roller. Fig. 8.9-Secondary roller used for cross-rolling pervious concrete to improve the ride quality of pavement. *f a #rt r rr ' R .° Fig. 8.13—Demonstration of curing with plastic sheeting -- immediately after compaction ; may be cut with the compacting roller(Fig.8.12).In all types Fig.8.10—Edging pervious concrete to improve appearance of roller-jointers,the junction of the blade and roller should of corners. incorporate a small concave-radius to reduce the square- edges at the top of the joint. Square edges have a greater tendency to ravel under traffic loading. If the contraction joints are saw-cut,the procedure should begin as soon as the pavement has hardened sufficiently to prevent damage to the surface. Only enough polyethylene cover material to saw cut the required areas should be removed(Fig.8.13).After sawing,the exposed areas should be soaked with water, which flushes the pores of the fines generated by sawing and ensure that sufficient water is present for proper curing.Immediately re-cover the exposed area with a polyethylene covering sheet as soon as saw cuts have been made. Fig. 8.11—Detailed view of jointing tool for pervious 8.6—Curing and protection The open pore structure of pervious concrete makes curing concrete, particularly important because of the larger surface area exposed to drying (dehydration). Immediate curing of concrete,and can occur in large placements even before the pervious concrete is vital for performance. Under favorable concrete has had time to cure enough for saw cutting. conditions of high humidity and low wind velocity,the cover Conventional concrete jointing tools may be used for small material should be placed no later than 20 minutes following placements such as sidewalks. A specially designed discharge. Under more severe environmental conditions the compacting roller-jointer with a blade that is at least 1/4 the cover material should be placed sooner. The cover material thickness of the slab, and with enough mass to force the should be heavy-duty polyethylene sheet, meeting the blade to cleanly cut the joint,is the tool of choice(Fig.8.11). requirements of ASTM C171, of sufficient dimension to In placements with wide lane widths, a longitudinal joint cover the entire width of a lane(Fig.8.13).Woven materials Copyright American Concrete Institute Provided by IHS under gcense with ACI Ucensee-CH2M Hill WOPdwtde/5960456046,User.Tmyan,Sean No reproductior or networking permitled without license from IHS Not for Resale.01/28/2015 12:09.07 MST PERVIOUS CONCRETE 522R-25 i 1 i M " rs . _ _,, : s _- Fig. 8.15 Painted lines visible on pervious concrete pavements. Fig.8.14—example of use of reinforcing bars to hold down curing material, mixtures,and 10 days for concrete mixtures that incorporate supplementary cementitious materials such as fly ash or slag. such as burlap and geotextile fabric should not be used as they will not hold the moisture in the concrete. Spray- It may be necessary in cold weather to increase these typical curing times.Striping should be applied only after the curing applied curing compounds do not produce acceptable results.strikeoff,compaction,and curing operations should be kept period has passed (Fig. 8.15). No traffic should be allowed on the pavement during curing, The general contractor as close together as possible to prevent the top surface of the pervious concrete from drying. Following the placement should take measures to prevent damage to the pavement due to abuse from construction operations. Specifically, the process,as soon as the strikeoff operation has moved on to a general contractor should prohibit removal of the curing new riser strip,the used riser strips should be removed and the material and prevent any traffic on the pervious concrete compaction operations begun.When adverse ambient weather pavement. Additionally, the general contractor should not conditions exist,such as high temperature,high wind,or low humidity, an evaporation reducer may be lightly sprayed on allow storage of building and landscaping materials on the the surface following strikeoff operations and before pavement surface as these materials can clog the pores or ,�- otherwise damage pervious pavements. compaction.Before covering,if the concrete has lost its sheen, it should be lightly misted with water but never sprayed. 8,7—Cold weather protection The polyethylene cover should completely cover all exposed pervious concrete is more sensitive to cold weather than surfaces and should be secured in place outside all pavement normal concrete (Section 8.1) and, therefore, pervious edges and at laps to prevent evaporation from the concrete and concrete construction may be suspended or curing blankets being displaced by wind(Fig.8.14).Reinforcing bars, lumber, used when ambient temperature during, and one day after, or concrete blocks may be used to secure the polyethylene placement is expected to fall below 40°F(4°C),Due to rapid cover to prevent it from being blown off. Dirt, sand, or other evaporation causing insufficient water for cement hydration, granular material should not be placed on top of the poly- hot water should not be used in batching pervious concrete. ethylene cover,as they may wash into the pores of the concrete During curing, measures should be taken to protect the during a heavy rainfall, or during removal of the cover. If pervious concrete from freezing while maintaining mois- wooden forms are used,the riser strips may be used to secure ture for the time necessary to achieve the desired strength. the sheets in place.The sheets should first be attached to the Curing blankets work sufficiently to serve this purpose. top of the form on one side of the lane by reattaching the riser strips to the top of forms with button-cap nails,with the poly- 8,8—Hot weather protection ethylene sheet sandwiched between the form and riser strip. In hot weather, transporting, placing, and compacting The sheet should then be pulled as right as possible to eliminate should be done as quickly as possible.An evaporation retardant creases and minimize the possibility of discoloration or may be applied to the surface of the concrete following the striping of the concrete.All surfaces of the pavement should strikeoff process to retard the loss of moisture on the be covered properly. Not doing so may result in raveling of surface. After consolidation and before placing the poly- the exposed areas.Any loss of moisture, such as from wind ethylene,the surface may be lightly misted with water or an getting under secured plastic, can be detrimental to the evaporation retardant if the surface appears to be losing its proper curing and strength development of the pavement. sheen appearance. The owner should be made aware of possible discoloration of the pavement surface due to the differential curing under the 8.9—Repairing pervious concrete pavements plastic sheeting.Over time the discoloration should even out 8.9.1 Grinding—High spots can be ground with a to a single gray color. weighted grinder; however,the grinder will cut through and For proper curing, the pavement should typically remain expose the aggregate in ground areas, changing the covered for at least 7 days for plain cement concrete appearance of the pavement. Copyright American Concrete Institute Provided by IHS under license with ACI Ucensee.CH2M Hill Worldwide/5960456046:User.Troyan,Sean No reproduction or networking pamined without license from IHS Not for Resale,01/2812015 12.09 07 MST 522R-26 ACI COMMITTEE REPORT Table 8.1—Typical maintenance activities for CHAPTER 9—QUALITY CONTROL INSPECTION pervious concrete placement AND TESTING Activity Schedule 9.1—General As with any engineered material,it is important to verify • Ensure that paving area is clean of debris Monthly the quality of a pervious concrete pavement. Tests • Ensure that the area is clean of sediments performed of the subgrade condition are to ensure adequate • Seed bare upland areas As needed density, support value, and permeability. Testing of the • Vacuum sweep to keep the surface free of sediment pervious concrete mixture should be conducted for both the Inspect the surface for deterioration or spatting Annually fresh and hardened properties of the concrete for quality assurance of density and thickness. Many of the present ASTM and AASHTO testing methods are applicable to a 8.9.2 Holes or low spots---Small holes(low spots) should pervious concrete pavement installation.Due to the physical be patched with an aggregate/epoxy blend or latex-modified characteristics of the material, however, not all traditional cement. To match the appearance of the pavement surface, concrete tests are appropriate for pervious concrete. the aggregate may be coated with wet cement and cured Due to the lack of test methods for this material, ASTM before patching. Large holes should be patched with Subcommittee C09.49 is developing test methods specifi- pervious concrete of the same mixture proportions as the rally for pervious concrete. As of 2008, five test standards original surface.When patching,it is highly unlikely that the were in development, including: Fresh Density and Void color of the patch will match the original surface material. Content, Compressive Strength, Flexural Strength, Field Epoxy bonding agents or latex-modified cement may be Permeability,and Hardened Density and Porosity. used to ensure proper bonding between the old and new surfaces. Acrylic paints have been used to disguise the area 9,2—Preeonstruetion inspection and testing of the patch with varied success. Unbonded thin sections of Determining the permeability of the subgrade and soil patch material may not remain intact under traffic loading.If analysis is particularly important in the design and construction in doubt,a full-depth repair is recommended. of the pervious concrete system.Basic tests of the properties 8.9.3 Utility cuts—In the event that a section of pervious of the subgrade should include a particle size analysis concrete is cut,a full-depth repair should be performed.This (ASTM D422), soil testing and classification (ASTM would include removing a square section the width of a D2487),and standard or modified proctor test(ASTM D698 placed lane such that the new material would be large or ASTM D1557).The results of these tests will provide the enough to maintain its structural integrity under loading. designer with the necessary data. The standard percolation test used for designing septic 8.10—Maintenance fields is not an appropriate test for determining subgrade Pervious concrete pavements are infiltration-based permeability for pervious pavements. A test section of the systems.Water passing through the pavement will carry with subgrade should be compacted to the specified density as it varying degrees of soluble and insoluble pollutants and part of the soil analysis before completion of the project trash. Most of this debris will be deposited on or near the design.A double-ring infiltrometer(ASTM D3385)or other pavement surface. Maintenance of pervious concrete suitable test should be performed to adequately test the pavements consists primarily of removing the accumulated permeability. For small projects, these tests may not be debris. Two commonly accepted maintenance methods are necessary,especially if the designer has previous experience pressure washing and power vacuuming. Pressure washing with similar local soils. may force some of the debris down through the pavement Normal soil testing procedures for subgrade density surface.This is effective,but care should be taken not to use (compaction) in accordance with a standard ASTM test too much pressure, as this will damage the pervious procedure should be performed before concrete placement as concrete.A small section of the pavement should be pressure part of a normal quality-control plan. washed using varying water pressures to determine the appropriate pressure for the given pavement.Power vacuuming 9.3—Inspection and testing during construction removes contaminants and debris by extracting them from As described in ACI 522.1, acceptance criteria should the pavement voids.The most effective scheme,however,is have two distinct aspects.The first criterion should be based to combine the two techniques and power vacuum after on the pervious concrete mixture as delivered and is based on pressure washing. A suggested maintenance schedule is the density. For each day's placement, or when visual found in Table 8.1. inspection indicates a change in appearance of the fresh Research conducted by the FCPA (1990) quantifies the mixture, at least one test should be conducted to verify the extent of contaminant infiltration in pervious concrete density of the material. The test of the mixture should be parking lot pavements. Five parking lots were examined as conducted in accordance with ASTM C1688/C1688M. part of the study, and the level of contaminant infiltration Acceptance should be based on ±5 lb/ft3 (80 kg/m3) of the was found to be quite low.Infiltration was found to be in the specified fresh density, The second acceptance criterion range of 0.16 to 3.4%of the total void volume after up to 8 years should be based on the completed pavement as outlined in of service, and brooming the surface immediately restored the following section.Field tests and inspections of pervious over 50%of the permeability of a clogged pavement. concrete should be performed by an individual certified as Copyright American Concrete Institute Prorded by IHS under license with ACI Llcensea.CH2M Hill Woridwlde/5960456046,User.Troyan,Sean No reproduction or networking permitted without license from HS Not for Resale,012612015 12 09.07 MST PERVIOUS CONCRETE 522R-27 30 Head of W Water Bead of Plumber's Puddy a Pervious Concrete Subsoil Fig. 9.1--Single-ring infiltrometer(I in. =25.4 non). both an NRMCA Certified Pervious Concrete Technician or Agreement as to what is essentially impervious and the method equivalent and an ACI Concrete Field Testing Technician— of measurement should be achieved before initial placement. Grade I or equivalent. Tests are being developed for determining the in-place permeability of pavements. One of the recent test methods 9.4—Posteonstruction inspection and testing that have been developed is the embedded single-ring The hardened density of a properly placed pervious pavement infiltrometer(Fig. 9.1) to determine the infiltration rates of should not vary substantially from the fresh density of the the pervious concrete system (Wanielista et al. 2005). This mixture.Coring of three samples of the pavement will result can be used either as a preconstruction tool or a postcon- in acceptance samples for thickness and density and should struction tool. The single-ring infiltrometer uses the same be tested for each lot of 5000 ft2 (465 m2) of pavement testing procedure as the double ring, as outlined in ASTM placed.Core samples should be obtained in accordance with D3385 with the modification of its embedment and the use ASTM C42/C42M not less than 7 days after placement.The of a single ring. It is postulated that this is a valid modifica- cores should be measured for thickness by an ACI certi- tion to test the infiltration rates of the entire system and avoid a lateral migration of water in the pavement alone.The depth fied Laboratory Technician according to ASTM C42/C42M and tested for density according to ASTM C140 (ASTM of penetration is an important variable and will be refined based on results from extensive field testing. Subcommittee C09.49 is developing methods specifically At no time should acceptance be based on the compressive for Pervious Concrete.). The placement thickness should be strength of the pervious concrete, either as delivered or as determined using untrimmed, hardened core samples. After cored from the pavement. Due to the relationship between thickness determination, the cores should be trimmed and compaction and compressive strength,there is a wide range measured for unit weight in the saturated condition as of strengths that can be generated from a single delivery of described in Paragraph 9.3,Saturation,of ASTM C140. pervious concrete. Additionally, there are no standard test After immersing the trimmed cores in water for 24 hours, methods for testing the compressive strength of pervious drain for 1 minute,remove surface water with a damp cloth, concrete.Typical coring procedures,when used on pervious and then weigh immediately. Tolerance for thickness concrete,disturb the cement paste matrix such that compres- reported as the average of three cores of each lot should not sive strength testing results may be inaccurately low. Local be more than 1/4 in.(6 mm)less than the specified thickness, experience with materials through completed projects, test with no single core exceeding 1/2 in. (13 trim)less than the panels,or both should give an indication whether a specific specified thickness,nor should the average compacted thick- mixture proportion will have sufficient strength to withstand ness be more than 1.5 in. (40 mm) more than the specified the stresses of the design traffic loads. thickness.The acceptable hardened density should be within ±5%of the approved hardened density from the test panels. CHAPTER 10—PERFORMANCE 10.1—General In addition, visual inspection of the cores will allow for Pervious concrete pavements more than 30 years old are still ' verification of the necessary open void space to facilitate in service. Information from controlled studies is available drainage. A visual inspection that shows a fully closed or concerning the long-term performance of pervious concrete severely restricted pore structure may indicate a pavement that pavements. The performance parameters discussed in will not function properly,and those sections demonstrated Chapter 10 include changes in infiltration rates, structural to be essentially impervious should be removed and replaced. distress,surface distress,and resistance to freezing and thawing. Copyright American Concrete Institute Provided by IHS under license with ACI Licensee-CF dwi 12M Hill Worlde5960458046 User.Troyan,Sean No reproduction or networiong permitted without Incense from IHS Not for Resale,01.2812 01 5 12 09.07 MST 522R-28 ACI COMMITTEE REPORT 10.2—Changes in infiltration rates investigation carried out in Florida (Wingerter and Paine Clogging occurs when foreign materials restrict the ability 1989) indicated that pervious concrete pavements with of water to flow through the pervious concrete pavements. surface raveling were caused by an inadequate w/cm, These foreign materials can be fines that enter the pervious inadequate compaction, or improper curing procedures.The concrete matrix or vegetative matter that collects on the investigators reported that the pervious concrete pavement surface or in the pores of the pervious concrete. Fines are projects had no signs of structural distress.Once a top layer of water-borne, wind-borne, or tracked onto the pervious loose surface material has been removed, the raveling often concrete pavement by traffic.Vegetative matter comes from stops. A modified version of an abrasion test to assess a trees or plants adjacent to the pervious concrete pavement. mixture's resistance to surface distress has been developed Water-borne fines come from stormwater runoff that starts (Offenberg and Davy 2008). outside the limits of the pervious concrete pavement and transports material onto the pavement. A geometric design 10.5—Resistance to freezing and thawing of the pervious concrete pavement that does not allow storm- The void structure of pervious concrete is not the same as water or traffic to introduce fines onto the pavement will the entrained air in regular portland-cement concrete. In minimize clogging. For example, pervious concrete pave- properly designed and installed pervious concrete pavements, ments should be placed at elevations above adjacent land- water drains through it to an underlying drainage layer and scaping, with the landscaping sloping away from the soil,and will not be retained in its void structure. When the pavement.Wind-borne fines are generally of limited volume pervious concrete is completely saturated and subjected to in many areas,but could be of concern in and areas.Vegetative freezing,however,the water has no place to drain.This can matter will routinely be deposited onto the surface of pervious result in excessive stresses on the thin cement paste coating concrete pavements,requiring periodic cleaning.Construction the aggregates, and may cause deterioration of pervious operations adjacent to pervious concrete pavement may also concrete installations. Some fully saturated non-air- cause fines to be deposited. Construction, therefore, should entrained pervious concrete had poor freezing-and-thawing be sequenced to avoid deposition of these fines. resistance when tested in the laboratory according to A field-performance investigation was conducted in Procedure A of ASTM C666/C666M (Neithalath et al. Florida in 1989 on pervious concrete pavements up to 13 years 2005a). It is possible to add air-entraining admixture to old (Wingerter and Paine 1989). The study concluded that pervious concrete mixtures to protect the coating paste,but the properly designed, constructed, and maintained pervious entrainment of air cannot be verified or quantified by current concrete pavements showed only small amounts of clogging standard test methods.Pervious concrete that is partially satu- after many years of service. The study also included the rated could possibly have sufficient voids for water move- percolation rate measurement on clogged pervious concrete ment,demonstrating good freezing-and-thawing resistance. pavement. The percolation rate of the clogged pervious ASTM C666/C666M is used to test fully saturated concrete pavement was still equal to adjacent grass. A more concrete samples.This does not simulate the performance of recent investigation of several field sites in Florida and other pervious pavement in the field because properly built instal- southeast U.S.locations has been carried out(Wanielista et al. lations in freezing-and-thawing environments contain a 2007).This study indicated that pervious concrete pavements mechanism for draining water out of the pavement. that were installed 10 to 15 years ago, with no maintenance Currently, there is no standard method for evaluating the requirements, are operating in a satisfactory manner with resistance to freezing and thawing of pervious concrete.The insignificant amounts of clogging. This study also looked at important factor is its ability to drain any water entering its potential rejuvenation methods in case clogging occurred, structure in the anticipated weather conditions. which included pressure washing and/or vacuum sweeping of National Concrete Pavement Technology Center the pavement. It also concluded that the most important (Schaefer et al.2006)tested several different mixture designs criteria for continued satisfactory performance of these for resistance to freezing and thawing. They determined that pavements were proper design and installation. saturated samples made according to one mixture design only had a 2%mass loss when subjected to 300 freezing-and- 10.3—Structural distress thawing cycles in accordance with ASTM C666/C666M Structural distress in pervious concrete pavements generally Method A. This mixture incorporated No. 4 aggregate, 7% takes two forms: cracking or subsidence due to loss of sand, 571 pounds of cement per cubic yard (338 kg/m3), subgrade support.Structural distress can be caused by heavy and a 0.27 w/cm.This mixture used both air entrainment and loads(beyond the structural capacity of the pavement),weak high-range water-reducing admixtures. Samples made subgrade materials, or horizontal water flow through the according to this mixture had a void content of 18.3%.They pervious concrete paving that washes away subgrade material. determined that the addition of binder latex to the mixture High surface contact pressures or a weak pervious concrete helped with resistance to freezing and thawing,but not to the surface can cause surface raveling. same extent as adding a small amount of sand to the mixture. ' These precautions are recommended to enhance the 10.4—Surface distress freezing-and-thawing resistance of pervious concrete: Surface distress is the removal of loose aggregate material Use an 8 to 24 in. (200 to 600 mm) thick layer of clean from the pervious pavement surface. A field performance aggregate base below the pervious concrete; Copyright American Concrete Institute Provided by IHS under ecense with ACI Ucensos.CHW Hil Worldwider5950458046,User.Troyan.Sean No reproduclion or networking permitted without license from IHS Not for Resale.01/23/2015 12.09.07 MST PERVIOUS CONCRETE 522R-29 • Attempt to protect the paste by incorporating air- roads,storage,and liquid/solid separation operations such as entraining admixture in the pervious mixture. Limited in agricultural manure dewatering. Each use has different and preliminary lab testing shows that fully saturated limitations and concerns. Further research would help to air-entrained pervious concrete had significantly better extend its use in these and in other applications and to verify freezing-and-thawing resistance when tested under its performance in various environments. ASTM C666/C666M; Some areas of research needs are as follows: • Place perforated PVC pipe in the aggregate base if the Strength determination and limitations; aggregate subbase is not thick enough to drain water Characterization of material structure; through the paving, to capture the water and let it drain Freezing-and-thawing and cold climate applications; away below the pavement;and Porous grout and other pore pressure reduction potentials; • Consider adding a small amount of sand to the concrete Stormwater management; mixture. Environmental filtering/remediation potential; Not every situation warrants all of these safeguards. The Surface deterioration and repair; safeguards are organized in the order of preference. For Development and standardization of broader testing example,a pervious concrete sidewalk at Pennsylvania State methods; University in University Park, PA, which is a hard, wet- a Nondestructive test methods for performance evaluation freeze area,has shown good performance over five winters and prediction; and has only an 8 in.(200 mm)thick layer of aggregate base Urban heat island effect,carbonation,and other thermal underneath the pervious concrete. There are many pervious properties; and concrete projects in Georgia, Pennsylvania, Tennessee, Other novel applications. North Carolina,and New Mexico subject to various freezing- and-thawing conditions that are performing admirably 11.2—Strength determinations and limitations (NRMCA 2004, 2007). Baas (2006) surveyed individuals Further research is needed to understand and improve the across the country and asked them to describe their observations strength of pervious concrete. The ability of pervious of pervious concrete freezing-and-thawing resistance. concrete to withstand heavy vehicular loads(typical delivery Respondents in Ohio, Minnesota, Northern Kentucky, truck or highway traffic) would enhance its use in a wide Tennessee, Indiana, and California did not report any range of applications.There has been some research into the freezing-and-thawing deterioration of pervious pavement compressive and flexural strengths of some pervious installations. Pervious concrete installations in the heavy concretes(Yang and Jiang 2003;Neithalath 2004;Marolf et snow areas of Colorado, Utah, Vermont, New Hampshire, al.2004;Wimberley et al.2001;Crouch et al.2003;Zouaghi Nevada,Montana,and Northern Arizona have also shown no et al. 2000).Delatte et al. (2007)measured the porosity and signs of deterioration due to freezing-and-thawing cycling. strength of several cores removed from in-service pervious The same can be said for the Maritime Provinces of Eastern concrete pavements.There are many different variations and Canada where a number of pervious concrete installations applications;however,for pervious concrete, the strength is have also taken place and where air-entrained conventional dependent on porosity(Neithalath 2004; Marolf et al. 2004; concrete is typically specified. Field performance was Mulligan 2005; Montes and Haselbach 2006). ASTM C39/ investigated for approximately two dozen pervious concrete C39M has therefore not proven to be an effective means of sites located in the states of Ohio, Kentucky, Indiana, measuring compressive strength. Placement techniques can Colorado, and Pennsylvania. Generally, the installations also develop vertical porosity distributions in the pervious evaluated had performed well in freezing-and-thawing pavement,which may have impacts on the flexural strength environments,with little maintenance required. They were, and other characteristics (Haselbach and Freeman 2006). however,relatively new,so there is a need to follow up later Additional research is needed to confirm that applicable on field performance(Delatte et al.2007). 28-day strengths can be reliably achieved in production Pervious concrete is historically not recommended in applications and into the various applications and strength freezing-and-thawing environments where the ground- characteristics of pervious concrete. water table rises to a level less than 3 ft(0.9 m) from the While pervious concrete is used more often for stotmwater top of the surface of the subgrade. New details,however, management in the U.S., interest in pervious concrete in have been developed for using pervious concrete on sites other parts of the world has focused on wearing course applica- with high groundwater tables and poorly draining soils tions.Europe,Japan,and Australia have investigated pervious (Ohio Concrete Ready Mixed Association) (http:// concrete for roadway use for noise reduction (Neithalath www.ohioconcrete.org). 2004) and improved skid resistance during rain events (Wang et al.2008).Pervious concrete in these cases is placed CHAPTER 11—LIMITATIONS, POTENTIAL using either the wet-on-wet method, where pervious APPLICATIONS, AND RESEARCH NEEDS concrete is placed overtop of fresh conventional concrete,or 11.1—Pervious concrete in cold climates as a surface to precast concrete panels. The quietest pave- The most widespread applications of pervious concrete ment in the world is a section of roadway in the Netherlands include paving and surface treatments to permit drainage. comprised of precast concrete sections containing a pervious These can take many forms, such as parking lot surfaces, concrete wearing course. There is concern about using Copyright American Concrete institute Provided by IHS under license with ACI Ucensee.CHW Hill Worldwider5960458046,User-Troyan,Sean No reproduelion or networking permitted without license from iHS Not for Resale,0128/2015 12:09.07 MST 522R-30 ACI COMMITTEE REPORT pervious concrete for road surfaces where traditional cold climates. Although there have been many pervious impervious designs avoid water seepage into the subbase, as concrete pavements installed in colder areas,several questions this may undermine the subbase and, therefore, lose critical remain to be conclusively answered so that pervious structural support under the impervious pavements. Much of concrete can be used with greater confidence and for broader this loss of material in the subbase,however,is due to hydro- application in cold climates.There are two main issues that static forces in this area of water seepage that occur from point should be further addressed:the first is the impact of freezing loads from vehicle wheels on the surface that push the soils and thawing on the concrete in a broader range of applications, away. Pervious concrete would of course allow for water and the second is to establish with greater certainty the seepage into the subbase,as water infiltration is its intention. potential impact of deicing salts on the concrete,particularly This may not,however,have the same destructive hydrostatic because the open pore structure allows for faster infiltration forces on the subbase,as the water could also move vertically of these salts into the concrete matrix than in traditional in the pervious column. Research into the water impacts on concrete pavement. The first known direct observation of strength and the underlying soils for additional applications of pervious concrete's behavior on freezing was a laboratory pervious concrete as road surfaces is needed. experiment by the U.S. Army's Cold Regions Research and More research is also needed into the fatigue performance Engineering Laboratory (Korhonen and Bayer 1989). of pervious concrete under load because that influences Samples of pervious concrete without air entrainment, pavement design. Preliminary research shows that pervious reinforcement,or other treatment for frost damage protection concrete has the same fatigue performance as plain concrete, were repeatedly frozen and thawed. At intervals during the but that work needs to be expanded(Tamai et al.2004). testing sequence, samples were removed from the freezing cycle and put under compressive force to test their loss of 11.3—Characterization of the material structure breaking strength.Those that had been frozen in dry or damp The properties and performance of any porous material (wetted, then drained) conditions showed little loss of depends extensively on its pore structure features such as the strength over 160 freezing-and-thawing cycles. A later total pore volume, pore sizes and their distribution, and the laboratory test (Yang and Jiang 2003) showed that after connectivity and tortuosity of the pore structure. Because 25 cycles of freezing and thawing in air, the unconfined pervious concrete is primarily used for stormwater compressive strength of five samples decreased 15 to 23%. management, the functional performance characteristic that Similar samples that had been frozen in water-filled is more often a concern for the end user is the permeability. containers, however, progressively deteriorated. Assuring Porosity is considered as the most important feature of the rapid drainage of a pervious slab into a well-drained base pore structure of porous materials,but it alone is insufficient reservoir,however,is a critical preventative measure against in providing a complete description of the material perfor- the effects of freezing. In cold regions,air-entraining agents mance.A higher porosity does not necessarily ensure higher are routinely added to concrete to protect it from frost permeability because the permeability is a function of the damage (AASHTO 1993). Experience primarily from pore surface area,pore sizes, and tortuosity.Using aggregates building construction suggests that air entrainment improves of different sizes in pervious concrete to produce the same the resistance of pervious concrete to damage from freezing- porosity has resulted in different permeability values and-thawing cycles as it does for dense concrete(FCPA 1990; (Neithalath et al. 2006); a proper understanding of the pore Monahan 1981; Neithalath et al. 2003). Liquid polymer and structure features and how it is influenced by the material latex additives may help by sealing the cement binder's parameters and mixture proportioning needs careful and micropores and preventing the entry of water.Supplementary thorough investigation. A few studies have reported the cementitious materials, various fibers, and liquid polymers influence of aggregate gradation and blending on the can enhance concrete's strength,limit shrinkage,and thereby porosity,pore sizes, and connectivity of pervious concretes improve its resistance to freezing-and-thawing conditions (Neithalath 2004; Neithalath et al. 2006; Low et al. 2008) and deicing chemicals(Pindado et al. 1999). using mathematical and statistical procedures. To develop Field performance was investigated for approximately two performance-based material design for pervious concretes, dozen pervious concrete sites located in the states of Ohio, significant research is needed in understanding the pore Kentucky,Indiana,Colorado,and Pennsylvania.In addition structure of this material. The macroporosity of pervious to field observations and nondestructive testing, laboratory concretes can often lead to crack arrest effects if the porosity testing was performed on cores removed from some of the and pore sizes are conducive. This influences the structural test sites. The installations evaluated had generally performance of the material. A comprehensive understanding performed well in freezing-and-thawing environments,with of material performance and a material design-based mixture little maintenance required. They were, however, relatively proportioning, therefore, can be accomplished only if the new,so there is a need to follow up later on field performance pore structure characteristics are well understood. (Delatte et al.2007). 11.4—Freezing-and-thawing and cold climate 11.5—Porous grout applications The technology of grout injection to provide structural More research would be valuable to evaluate the efficacy support beneath foundations has been practiced in construction of known technologies in protecting pervious concrete in since 1802(Houlsby 1990).The materials have traditionally Copyright Anne—Cani InsbVe Provided 6y IHS under license with ACI Ucensee-CH21v!Hill Woridwidei5960458046,User.Troyan,Sean No reproductlor or networking permided without license from IHS Not for Resale,01128/2015 12.09.07 MST PERVIOUS CONCRETE 522R-31 been a mixture of portland cement,water, and often a filler, oxygen and increasing the biochemical oxygen demand such as sand.This is mixed into slurry and pumped into the (BOD). Creating or increasing BOD stress, can, under the desired area,usually the interface between existing foundations most extreme conditions, lead to events such as fish kills. and the in-place soil or rock, forming a structural bond that Plant growth in pervious concrete systems should be is rigid and not normally pervious.There are cases,however, minimal due to the lack of sunlight.In many cases,but not in in which hydraulic conductivity is desired so that the natural all,the initial stormwater runoff will carry a higher concentration hydrostatic forces can be relieved without causing deterioration of contaminants than later runoff. The initial rain will wash due to saturation, erosion, and piping. This has led to the off the surface somewhat. The part of the runoff with a widespread use of French drains(gravel),drainage blankets, higher contaminant concentration is termed the first flush.In and fabrics for drainage and prevention of erosion and areas with long periods between rain, a seasonal first (geotextiles), where foundations are accessible during flush may also occur. One of the common goals of runoff construction. This type of pumped-in-place pervious grout control is to capture the first flush. This is particularly true would fill a basic need in the construction industry,particularly when dealing with small catchment(drainage)areas. in projects involving site remediation and retrofit. Example The first flush may not occur in some of the following cases: applications of this pumped, porous material include 0 Large catchment areas rarely show a first flush, as a remediation of dams (Weaver 1991), tunnels, highways, steady stream of the first flush of areas farther and canals,railroads,and environmental treatment.Porous grout farther away from the outlet arrive over time; materials that could be pumped were studied and reported by There may not be a first flush if pollutants are not easily the Bechtel Corporation in 1995.The studies encompassed a washed away or dissolved; and wide range of pumped materials that had drainage properties. 0 Differences in pollutant load over time may be difficult to Several mixture proportions were developed and are in the detect if the supply of pollutants is essentially continuous testing phase(Yen et al.2002). (for example,sediment from bare,easily eroded ground). Relatively simple rules of thumb for selecting or 11.6—Stormwater management approving designs and control features have often been used There are two important aspects to stormwater management: due to lack of sufficient local data combined with seasonal runoff control and water quality control. There have been variations or effects and antecedent rainfall events.As a crude several initial studies into the infiltration rates, hydraulic rule of thumb,the first flush occurs during the first 30 minutes conductivity, and rational runoff coefficient for pervious to 1 hour for small sites,such as parking lots. When pervious concrete (Wanielista et al. 2007; Montes and Haselbach concrete is used,the first hour of rain will generally be captured 2006;Wimberley et al.2001;Valavala et al.2006),Additional as a minimum.It is reasonable to assume that,at a minimum, study is needed for infiltration through sloped pervious the part of the runoff with the highest pollution load will also concrete surfaces and the variation of infiltration rates with be captured. Pervious concrete pavements will carry the first aging and other environmental impacts.Water-quality issues flush into the pores of the concrete, and additional rain will for watersheds are increasingly important. Much of the carry the pollutants further into the system without returning material washing into streams, rivers, and eventually into them to the runoff stream.The natural cleaning effects of soil groundwater comes from surface runoff contaminated with may then further clean the runoff.Adoption of specific types of materials applied to the ground surface. The contaminants mitigation devices and features depends on the site use, the can be excess fertilizers and nutrients,pesticides,road salts, types and quantities of pollutants anticipated, the estimated or other materials intentionally applied,from spills or debris runoff, and site characteristics. While capturing the first flush such as gasoline and petroleum products from oil drips,and of an area is often desirable,the disposal of the first flush and tire abrasion or other residue such as litter,animal waste,and cleaning of the catch basin after removing the first flush can be fine dust.Some materials are quickly picked up or dissolved technically challenging and expensive. and carried by runoff while others, including insoluble Research is needed to establish or confirm many of the obser- greases and low-volatile content oils,may not. vations and assumptions regarding pollution trapped by pervious Another source of runoff contaminant has been ineffective or concrete pavements (Rushton 2000). Several of the assump- unenforced control of runoff on bare earth,often from sites tions related to water quality that need to be confirmed are: under development. Lack of effective erosion controls has Greases and low volatile content oils occurring resulted in significantly increased sediment loads in some routinely on parking areas,such as oil drips from vehicles, areas. By controlling excess surface runoff using a properly will probably be adsorbed onto the surface of the designed pervious concrete pavement system,a reduction in pervious concrete or into the pores of the pervious peak stream velocity is possible. Erosion of streambeds is concrete,or will be degraded by the microbial community reduced, thereby reducing the sediment load carried by the in the system(Pratt et al.2002)and will not be transferred stream. Washing large amounts of nutrients (compounds to groundwater or surface water in any significantly high in nitrogen and phosphorus) into the watershed has different quantities than with detention ponds. Recent numerous consequences. Plant growth, particularly microbial studies have investigated the efficiency of pervious biomass such as phytoplankton and algal blooms, is concretes in containing vehicular oil spills (Bhayani et increased. Although plants produce oxygen while alive, al. 2007; Deo et al. 2008). Pervious concrete mixtures when they die, they decay, using up available dissolved with porosities ranging from 13 to 25%were proportioned Copyright American Concrete Institute Provided by IHS under license with ACI LJcer5ee•CH2M Hid Worldwide/5960456046,User-Troyan,Sean No reproduction or retwmk ng permitted without icense from IHS Not for Resale.0128/2015 12 09.07 MST 52213-32 ACI COMMITTEE REPORT using two different-size aggregates. The oil retention pavement. Research is not only needed for surface treatments and recovery was experimentally determined on 2 in. that can extend the life of a pervious concrete pavement and (50 mm) slices of pervious concrete specimens using a add to its sustainability and aesthetics,but for materials and y partition gravimetric method. An idealized pore-aperture methods for pavement repair as well. model was used to develop a modeling framework for the oil retention in pervious concrete. The material 11.9—Development and standardization of parameters, as well as the input features that are most broader testing methods likely to influence the retention and recovery of oil, The current established testing methods for concrete are were identified. A genetic programming-based model in many cases not applicable to pervious concrete. Either was used to predict the oil retention in pervious new or modified testing methods need to be established that concrete specimens. It was found that this modeling take into consideration the unique characteristics of methodology provides good estimates of oil retention; pervious concrete. The most frequently cited variable that • Water carrying dissolved solids and nutrients into the is tested on pervious concrete is porosity. There are, soil from the pervious concrete will undergo natural however, many different definitions for porosity (effective filtering and purification such that the water reaching the porosity,total porosity,drained porosity,void content)that groundwater table will be of roughly the same quality as are not well defined and are equally important, depending runoff soaking in directly from the surface;and on the application and design need of the pervious system. • The maximum draw-down time for a pervious concrete A variety of porosity measurement techniques have been system should be 3 to 5 days, which is consistent with investigated on pervious concretes (Crouch et al. 2003; detention pond design, and may occur with pervious Neithalath 2004;Marolf et al.2004;Neithalath et al.2006; concrete pavements constructed on clayey soils. As Monies et al.2005).Standardization or referencing to these light is not available much past the surface,growth and techniques is crucial for comparison of most characteristics subsequent decomposition of biomass due to high and for design criteria of pervious concrete systems. nutrient loads in the runoff will be minimal. As Field quality control and assurance tests need to be pervious concrete is not saturated for much of its established.Methods for testing workability or consistency, service life,the pores are relatively small but not capillary like the slump test for plain concrete, are necessary quality in size,air is available to a large surface area compared control tools for the concrete producer, as are tests for with the volume, and there is little difference in the compressive strength and air entrainment. Owner's quality decomposition of biodegradable organic material assurance tests for strength and durability are significant compared with decomposition on the surface. needs for pervious concrete pavements. There are also testing methods that need to be developed 11.7—Environmental filtering/remediation potential for pervious concrete that are not similar to any methods In addition to its potential for filtering or remediating traditionally used in the concrete industry.For instance,field stormwater-related pollutants (Tamai et al. 2004), there is infiltration rate methods similar to those for other porous interest in pervious concrete as a material for other environ- media are needed. In addition, pollutant removal testing mental filtering or remediation purposes, especially in the methods would be beneficial to design and specify pervious agricultural and waste treatment industries. Pervious concrete for its potential water quality benefits. concrete has already been used for greenhouse floors.There is also interest in using pervious concrete as a paved surface 11.10---Nondestructive determination of for manure or sludge dewatering. performance and properties One of the significant impediments to the widespread use 11.8—Surface deterioration and repair of pervious concrete is the absence of test methods to evaluate As with any other pavement surface, especially those or predict the performance of the material as placed and in under heavy vehicle loads,there is expected to be aging and service.Due to its open pore structure,conventional methods deterioration of the pervious concrete surface over time. of concrete performance estimation are not applicable to Offenberg and Davy (2008) proposed a test method for pervious concrete. Of late, some novel test methods have determining the raveling potential of a pervious concrete been attempted for nondestructive pervious concrete property mixture.This method uses a 4 in. (100 mm) tall,4 in. (100 estimation. Because it is easy to saturate the pervious mm) diameter cylindrical specimen that has only been concrete specimen with an electrolyte of known electrical cured for 7 days. The specimen is tumbled in an apparatus conductivity, the emphasis has been on using electrical typically used for ASTM C131. The raveling potential property-based methods for performance estimation. The relates to the difference in specimen mass before and after use of a modified parameter that can be derived from electrical testing. Further research is needed to quantify a mixture's conductivity has been used to predict the permeability of potential for surface deterioration after field application pervious concrete fairly accurately (Neithalath et al. 2006). and service, and to correlate this back to fresh properties. Similar methods have also been extended to predict the Typical concrete surface treatments may not be applicable acoustic absorption behavior of pervious concrete.Delatte et to pervious concrete, as many are surface sealants and may al. (2007) used ultrasonic pulse velocity (UPV) to investigate effectively impact the infiltration capability of the pervious in-service pervious concrete pavements as well as extracted Copyright American Concrete Institute Prcwded by IHS under license with ACI Licensee.CH210 Hill Worldwide15 9604 58 0 46.User.Trcyan,Sean No reproduction or networking perm,tted without license from IHS Not for Resale.0128/2015 12 09:07 MST REPORT ON PERVIOUS CONCRETE(ACI 522R-10) 33 cores. Ultrasonic pulse velocity was found to correlate well Some applications are as road surfaces and sound barriers with engineering properties such as strength and void ratio. (Neithalath et al. 2005b; Tamai et al. 2004). A number of European studies relating to sound absorption characteristics 11.11—Urban heat Island effect, carbonation,and of pervious concrete are available and so are a few studies other thermal properties carried out in the U.S. (Neithalath 2004). Conventional, dark pavement surfaces are considered to be large contributors to the urban heat island effect.There is CHAPTER 12—THE ENVIRONMENT AND a unique aspect of pervious concrete that may influence its PERVIOUS CONCRETE impact on the urban heat island effect—its porous nature. Pervious concrete is a unique and innovative means of Many porous media are considered to be insulators, and managing stormwater (Fig. 12.1). From an environmental pervious concrete may have some of these characteristics. perspective, among its primary benefits is the reduction in Pervious concrete, however, also consists of intercon- the total volume of runoff that otherwise carries substantial nected voids that may influence convection of heat into or amounts of pollutants into our local streams, rivers, lakes, out of the earth's surface. It is unknown which heat and oceans. Costly infrastructure is committed to dealing transfer processes dominate, and under what conditions. with the sheer volume of stormwater and the ability to effec- There is little or no research into the urban heat island impacts tively remove significant amounts of pollutants is increas- of using pervious concrete over other impervious pave- ingly challenging. By infiltrating the stormwater, a ment surfaces; therefore, additional information is greatly recommended best management practice of the U.S.EPA for needed (Ferguson 2005). Similarly, the thermal aspects of dealing with runoff, not only is the volume of stormwater pervious concrete may be important for determining remedia- greatly reduced but pervious concrete effectively provides tion rates and other environmental process rates. "first flush pollution mitigation" where approximately 90% The use of pervious concrete may also have an impact on of the pollutants are carved away in the first inch(25 mm)of another aspect related to the global climate. There has been typical significant rain events.The filtration provided by the much research and concern about the levels of carbon voided matrix within pervious concrete retains organic dioxide in the atmosphere. Many researchers have pollutants and naturally occurring microbial growth may performed life-cycle analyses of the contribution to the provide further treatment before the pollutants that remain carbon dioxide in the atmosphere from many construction are eventually converted by native soils. materials. Concrete has been shown to be a contributor in The infiltration provided by pervious concrete recharges two ways:the first is in the energy use for making cement,if groundwater,provides irrigation to nearby surface vegetation the energy source is a nonrenewable source; and the second and tree root systems, and mitigates "thermal pollution," is in the chemical process that forms cement from its source where traditional runoff significantly contributes to an materials, which releases carbon dioxide as a by-product. increase in water temperatures negatively affecting the habitat Therefore, even if the carbon dioxide component from the of fish, aquatics, and vegetation within various bodies of energy use was eliminated, the manufacture of pervious water.The potential to harvest water for a variety of purposes concrete would still result in a net production of carbon is also enhanced.Pervious concrete may also absorb and retain dioxide. There is some current research, however, into the less heat,and may require less night illumination than the most absorption of carbon dioxide back into concrete structures commonly used conventional pavement,giving it the potential over time. This process, referred to as carbonation, to positively impact urban heat island mitigation and carbon involves a chemical change and can balance some of the footprint through energy reduction. carbon dioxide gain from the cement manufacturing process.Carbonation is usually slow under ambient conditions, but faster when traditional concrete has large surfaces exposed to the air. An example is when concrete is broken up and recycled for fill. Pervious concrete has a much larger surface area exposed than other concrete applica- tions to the air, and may have a faster rate of carbonation. Research into this rate is needed so that the overall impact of using pervious concrete on the amounts of carbon dioxide in our atmosphere can be better understood. 11.12—Other novel applications and uses There are many other novel applications for pervious concrete other than as pavement surfaces for stormwater control or as an environmental filter for dewatering l processes. Its lower density may benefit its use in building construction to reduce structural needs. s *t Pervious concrete is sometimes referred to as EPC and has been shown to have some benefits in sound absorption. Fig. 12.1—Pervious concrete stormwater management system. Copyright y IHS under Concrete Institute American Concrete Institute Cc----A s ens^-i ^^ -^`^^ Promdec by IHS under license w;th ACI Uconsee-CHV HFI Worldwide/5960456046,User-Troyan.Sean No reoroduclion or networking permitted without lcense from IHS Not for Resale,0128 2015 12:09.07 MST 34 REPORT ON PERVIOUS CONCRETE(Act 522R-10) 12.1—Pervious concrete and the LEEDTM green for SS-c6.1. Note that percent imperviousness is not the building rating system same as percent impervious. Percent impervious represents When pervious concrete is used in building site design, it the portions of a project site covered with essentially imper- can aid in the process of qualifying for numerous credits in vious surfaces such as roofs and traditional paving. the Leadership in Energy and Environmental Design However, percent imperviousness is based on all the site (LEEDT'11) green building rating system (Version 3.0 surfaces and their contribution to runoff. It is calculated in a LEEDT"' 2009) as administered by the U.S. Green Building manner similar to the rational runoff coefficient(Haselbach Council. With rapid changes in the LEEDTM` system and 2010). pervious concrete technology, the committee will post SS-c6.2 requires that 80% of the average annual post- current information about this topic on the ACI Concrete development total suspended solids (TSS) load is removed Knowledge Center at http://www.concrete.org/tkc/ from 90%of the average annual rainfall.This amount of rain knowledge—center.htm. can be approximated in the LEEDT"' 2009 reference guide LEEDTM 2009 provides a framework for evaluating (USGBC 2009)as the first 1.0,0.75 or 0.5 in. (25, 19 or 13 building and site performance,and establishes sustainability mm) of a rain event in humid, semiarid, and and regions, goals by creating several minimum mandatory requirements respectively. The guide also indicates that infiltration of and then awarding points in five main credit categories: these volumes of rain onsite is an effective method for TSS sustainable sites (SS), water efficiency (WE), energy and removal.Therefore,pervious concrete would be an accepted atmosphere(EA),materials and resources(MR),and indoor method for attaining the point for SS-c6.2. environmental quality(IEQ).There are also two other credit Guidance is not given concerning the amount by which categories: the innovation and design processes category requirements in both SS-c6.1 and SS-c6.2 must be exceeded (ID), which allows for innovation in design and exemplary to receive an additional exemplary performance point in performance; and the regional priorities category (RP), LEEDT"' 2009. Extensive use of pervious concrete systems which allows for additional credit points based on important may have the potential for obtaining this additional point and regional environmental or resource needs. LEEDT"' 2009 it is recommended that designers inquire as to the avail- points are not necessarily gained directly by the use of a ability of exemplary performance in stormwater manage- product, but rather by meeting a specific sustainability goal ment with the use of pervious concrete for their project on a of the rating program. case-by-case basis. In the future, more guidance might be Pervious concrete can contribute to many LEEDT"' 2009 found in the addenda to LEEDT"'2009 or the credit interpre- categories, including: Sustainable Sites, Water Efficiency, tation replies (CIRs) available from the USGBC on the Materials and Resources, and Innovation in Design (RMC www.usgbc.org website. 2006;Ashley 2008;USGBC 2005,2009). 12.1.2 Heat Island Effect: LEED 7,112009 Credit SS-c7.1 Some specific credits where pervious concrete can aid the Heat Island Effect—Non-Roof—The intent of this credit is to designer in meeting sustainability goals include: reduce heat islands (thermal gradient differences between 12.1.1 Stormwater Control: LEEDTtr2009 Credits SS- developed and undeveloped areas) to minimize impact on c6.1 Stormwater Design — Quantity Control and SS-c6.2 microclimate and human and wildlife habitat, and reduce Stormwater Design—Qnaltity Control—The intent of these urban energy demands. This credit requires any combination credits is to limit disruption and pollution of natural water of the following for 50% of the site hardscape (sidewalks, flows by managing stormwater runoff, increasing on-site parking lots,drives,and access roads):shading within 5 years infiltration, and eliminating contaminants. Each are worth of occupancy,paving materials with a solar reflectance index one point, and a project can earn an additional exemplary (SRI) of at least 29,and/or an open-grid paving system. The performance point by going beyond the credit requirements definition of open-grid paving system for the purposes of SS- for both quantity and quality control. Pervious concrete can c7.1 is one which is at least 50% open and is vegetated. (A contribute to these credits by reducing stormwater flow, second method to achieve this credit includes providing under allowing water to soak through and infiltrate to the ground cover parking areas for 50%of the parking spaces.) below.Pervious concrete can also reduce the pollutant loads As noted, LEEDT"' 2009 gives credit for minimizing the by filtering contaminants as the water is transferred through heat island effect by the addition of shading, which may be the pavement. provided by trees planted in or around parking lots and other On building sites where the existing imperviousness is hardscapes. Pervious concrete pavement is ideal for greater than 50%, Credit SS-c6.1 requires reducing the rate protecting trees in a paved environment. (Many plants have and quantity of stormwater runoff by 25% from the 2-year, difficulty growing in areas covered by impervious pave- 24-hour design storm. On building sites where the existing ments, sidewalks, and landscaping because air and water imperviousness is less than 50%,one of the options specifies have difficulty getting to the roots.)Pervious concrete pave- that the post-development peak discharge rate and quantity ments or sidewalks allow adjacent trees to receive more air from the site should not exceed the predevelopment peak and water and still permit full use of the pavement. rate and quantity for both the 1-year and also the 2-year 24- Pervious concrete may also act to reduce the heat island hour design storms. In many cases, by incorporating a effect by absorbing less heat from solar radiation than darker pervious concrete pavement system on site, the project can pavements. However, permeable pavements do not reflect meet these criteria and thus obtain the LEEDTM 2009 point solar radiation in the same manner as traditional impervious Copyright American Concrete fnstlmte American Concrete Institute Co ri hi,•'""^'^^^' •• ••^ '^ Provided by i.HS under license wen ACI PY 9 <rcensee.CH2M H91 Worldwidei5960458046,User.Troyan Sean No reproduction or networking permided without license from IHS Not for Resale.012&2015 12:09.07 MST REPORT ON PERVIOUS CONCRETE(ACI 522R•10) 35 also contribute to this. As test sections are highly recom- mended for most critical applications of pervious concrete, doing such early enough to allow for in-place specimens to be evaluated for solar reflectance index(SRI)prior to place- ment and be potentially prequalified, may be a practical means of acceptance. -c" ' 12.1.3 Water Efficiency: LEED M'2009 Credit WE-cl Water Efficient Landscaping—The intent of this credit is to limit or eliminate the use of potable water or other natural surface or subsurface water resources available on or near the project site, for landscape irrigation. Two points are awarded in LEEDTM 2009 if potable water for irrigation is reduced by 50% when compared to a mid-summer baseline case(Option 1).Pervious concrete systems can facilitate this Fig. 12.2—Supplementary cementitious materials.From left in two ways. The granular sub-base (retention layer) under to right: fly ash (Class C); metakaolin (calcined clay); pervious concrete can be used to store stormwater for irriga- silica fione; fly ash (Class F); slag; and calcined shale. (Reprinted with permission from Portland Cement Association.) [ion, helping to reduce the potable water demand. In addi- tion,pervious concrete may aid in retaining water in the soils near landscape beds, reducing the need for irrigation. If no pavements,even those of similar color and material design; irrigation is required for a project, or if no potable water is therefore, pervious concrete is not eligible for this credit in used and the overall irrigation needs are less than half the most cases based solely on the SRI.It is hoped that modified baseline,then two additional points may be earned for a total SRI criteria may be applied to pervious concrete in future of four points in WE-cl (Option 2). revisions or addenda to LEEDTM SS-c7.1.The reason for this 12.1.4 Materials and Resources: LEED""2009 Credit is that the relatively open pore structure of pervious concrete MR-c4 Recycled Content—The intent of this credit is to may store and transmit less heat and, therefore, helping to increase the demand for building products that have incorpo- lower heat island effects in urban areas(Kevern et al. 2009; rated recycled content material reducing the impacts Haselbach et al. 2011). Designers may wish to submit a resulting from the extraction of new material. The require- credit interpretation request (CIR) to the USGBC for ments for these credits are the use of materials with recycled pervious concrete applications based on a combination of its content such that the sum of post-consumer recycled content porosity and SRI,to ask for a point(s)for reducing the urban plus one-half of the pre-consumer recycled content consti- heat island effect,based on new literature on the subject and tutes at least 10%,20%,or 30%(based on the dollar value of also citing that the International Code Council (ICC) has the material),for one point,two points,or a third exemplary modified the International Green Construction Code(IGCC) performance point, respectively, of the total value of mate- in Version 2 to allow for pervious concrete to be applied as rials in the project.Most ready mixed concrete contains recy- a countermeasure to the urban heat island effect, regardless cled materials in the form of supplementary cementitious of its SRI (ICC 2010). This newest version of the IGCC materials (SCMs) such as fly ash, slag, or silica fume (Fig. states the following exception for the solar reflectance 12.2). The use of SCMs or recycled aggregate in pervious criteria of 29: "Pervious concrete pavements shall be concrete or base material contributes to recycled content allowed to be considered as a hardscape material that is needed for this credit.Supplementary cementitious materials deemed to comply with the criteria for solar reflectance and are considered pre-consumer recycled material and recycled need not be tested in accordance with ASTM E1980.".Note aggregate from a demolished project are considered post- that SS-c7.1 is worth one point in LEEDTM 2009,but is also consumer recycled material.This credit has special calcula- subject to an additional exemplary performance point if all tions specifically for cement and SCMs.In most cases,for a the handscape on the site is effectively shaded,open graded, composite material, LEEDTM 2009 specifies that one calcu- or has a high solar reflectance. late the dollar value of the recycled content as a fraction of As a generalization, a concrete producer can increase the the mass of the material that is recycled,times the total value solar reflectance of concrete through materials selection. As of the material.However,because cement is one of the most portland cements can vary in color,a lighter-colored cement expensive ingredients in concrete by mass, this calculation could improve the solar reflectance of a pervious concrete can be modified so that the dollar value of the SCM recycled mixture as well could the introduction of integral coloring content is a fraction of the mass of the cementitious material (white), and the potential use of a supplementary cementi- only,times the value of cement. tious material such as slag (usually noticeably lighter than 12.1.5 Regional Materials: LEED''m2009 Credit MR-c5 conventional plain gray cement).The size,shape,gradation, Regional Materials—The intent of this credit is to increase and color of the aggregates could affect the amount of"open demand for building products that are extracted and manu- gradedness," which contributes to the lack of comparative factured locally,thereby reducing the environmental impacts albedo in pervious concrete. The technique and type of resulting from their transportation and supporting the local equipment a contractor uses for placing the concrete could economy.To meet the intent of this requirement, 10%(based Copyright American Concrete Institute Provided by IHS under license with ACI American Concrete Institute Cc�•^^�'^''�a^�^"^� iJcensee.CH2M HYI WorWwide/5%o458046,User-Trayan,Sean No reproduction or networking peaMOed without.!came from IHS Not for Resale.01 2812015 1 2,09:07 MST 36 REPORT ON PERVIOUS CONCRETE(ACI 522R-10) toward a project as an IDc1, and a maximum total of five LJL IDcI points.The other IDc1 points may come from innova- tion. Therefore, if other areas of exceptional environmental or energy performance related to pervious concrete systems can be shown,then these may have the potential for an IDcI innovation point. 12.1.7 Regional Priorities: LEED r.N 2009 Regionally Priorities—The USGBC chapters in the country were allowed to pick six credits in the five main LEEDTM catego- ries that they determined were priorities for their region.The regional priority (RP) credits are listed for each zip code in each state as they become available at www.usgbc.org/ LEED2009.If a project earns one of the credits in this list of six for the zip code in which the project is sited,then an addi- tional point is added to the point total for a maximum of four extra points in the RP category. The credits for which Fig. 12.3—Pervious concrete parking lot. pervious concrete may play a role are sometimes listed.For instance,in the State of Washington, there are several loca- tions that have designated WEc I (Option2)as eligible for an additional RP point, and other locations have designated SSc6.1 for RP credit.Similarly,WEc i (Option 2)and MRc5 r (20% compliance) are frequently listed in Florida, and both -} SSc6.l and SSc6.2 are often eligible for extra RP points in a areas of Ohio. gat"rr r� y � fi' CHAPTER 13—REFERENCES 13.1—Referenced standards and reports The documents of the various standards-producing organi- zations referred to in this document are listed below with ► their serial designations.The users of this document should � e check directly with the sponsoring group if it is desired to refer to the latest revision. Fig. 12.4—Per4ous concrete parking area. American Association of State Highway & Transportation Officials(AASHTO) M-157 Standard Specification for Ready-Mixed Concrete on cost)of the total materials should be harvested,extracted, T-180 Standard Method of Test for Moisture-Density or recovered within 500 miles (805 km) of the project site. sing a 4.54 kg (10-tb) U An additional point is awarded for 20% regional materials. Relations of Rammer and a Soils Soils (18-in.)Drop The majority of materials in pervious concrete and most ready mixed concrete are considered regional materials. American Concrete Institute Projects with large amounts of concrete may meet the 301 Specifications for Structural Concrete required 10% or 20% regional materials to meet this credit 325.12R Guide for Design of Jointed Concrete Pavements (Fig. 12.3 and Fig. 12.4),LEEDTM 2009 also allows a third for Streets and Local Roads exemplary performance point for MR-0. It is listed in the 330R Guide for Design and Construction of Concrete reference guide as being awarded for 30%regional materials Parking Lots (USGBC 2009); however, earlier versions of LEEDTM 522.1 Specification for Pervious Concrete Pavement awarded it for a minimum of 40% regional materials. It is recommended that project designers check the LEEDTIA ASTM Intei7tational 2009 addenda provided on the USGBC website C29/C29M Standard Test Method for Bulk Density (www.usgbc.org)to determine if the requirements have been ("Unit Weight")and Voids in Aggregate modified for exemplary performance. C33/C33M Standard Specification for Concrete 12.1.6 Innovation in Design:LEED T1120091Dc1 Innova- Aggregates Lion in Design—As previously discussed, several of the C39/C39M Standard Test Method for Compressive ( ) LEEDTM 2009 credits allow for an additional point for exem- Strength of Cylindrical Concrete Specimens plary performance(EP).This point is counted in the innova- C42/C42M Standard Test Method for Obtaining and tion in design(ID)category as an IDcI point.LEED'm 2009 Testing Drilled Cores and Sawed Beams of allows for a maximum of three EP points to be counted Concrete Copyright American Concrete Institute American Concrete Institute Copyright"�sa^`^^^I '"""^^ ' `- ^ P;o,ded dy IHS under license with ACI 0l4nsee-C)12M Hill Woddwide15960456046,User.Troyan,Sean No reproduction or networking permitted without license from IHS Not for Resale,0126J2015 12.09.07 MST REPORT ON PERVIOUS CONCRETE(ACI 522R-10) 37 C94/C94M Standard Specification for Ready-Mixed D3385 Standard Test Method for Infiltration Rate Concrete of Soils in Field Using Double-Ring Infil- C131 Standard Test Method for Resistance to trometer Degradation of Small-Size Coarse Aggre- E1050 Standard Test Method for Impedance and gate by Abrasion and Impact in the Los Absorption of Acoustical Materials Using a Angeles Machine Tube, Two Microphones, and a Digital C138/C138M Standard Test Method for Density (Unit Frequency Analysis System Weight), Yield, and Air Content (Gravi- metric)of Concrete These publications may be obtained from the following C140 Standard Test Methods for Sampling and organizations: Testing Concrete Masonry Units and Related Units American Association of State Highway & Transportation C150/C150M Standard Specification for Portland Cement Officials(AASHTO) C171 Standard Specification for Sheet Materials 444 North Capitol Street N.W.,Suite 249 for Curing Concrete Washington,DC 20001 C260 Standard Specification for Air-Entraining www.aashto.org Admixtures for Concrete American Concrete Institute C494/C494M Standard Specification for Chemical 38800 Country Club Drive Admixtures for Concrete Farmington Hills,MI 48331 C595/C595M Standard Specification for Blended www.concrete.org Hydraulic Cements C618 Standard Specification for Coal Fly Ash and ASTM International Raw or Calcined Natural Pozzolan for Use 100 Barr Harbor Dr. in Concrete West Conshohocken,PA 19428 C666/C666M Standard Test Method for Resistance of www.astm.org Concrete to Rapid Freezing and Thawing C989 Standard Specification for Slag Cement for 13.2—Cited references Use in Concrete and Mortars AASHTO, 1993, Guide for Design of Pavement Strictures, C1157/C1157M Standard Performance Specification for Washington,DC,640 pp. Hydraulic Cement Ahmad, S. H., and Shah, S. P., 1985, "Structural Proper- C1240 Standard Specification for Silica Fume ties of High Strength Concrete and its Implications for Used in Cementitious Mixtures Precast Prestressed Concrete," PCI Journal, V. 30, No. 6, C1399 Standard Test Method for Obtaining Nov./Dec.,pp.92-119. Average Residual-Strength of Fiber-Rein- Ashley, E., 2008, "Using Pervious Concrete to Achieve forced Concrete LEEDTM Points,"Concrete in Focus,National Ready Mixed C1688/C1688M Standard Test Method for Density and Void Concrete Association,Skokie,IL,Winter,4 pp. Content of Freshly Mixed Pervious Atlanta Regional Commission,2001,Georgia Stornwater Concrete Management Manual,pp. 3.3-33 and 3.3-40. Baas, W.P.,2006, "Pervious Concrete Pavement Surface D422 Standard Test Method for Particle Size Durability in a Freeze-Thaw Environment where Rain,Snow Analysis of Soils and Ice Storms are Common Occurrences," Ohio Ready- D448 Standard Classification for Sizes of Aggre- Mixed Concrete Association,4 pp. gate for Road and Bridge Construction Backstrom, M., 2000, "Ground Temperature in Porous D698 Standard Test Methods for Laboratory Pavement During Freezing and Thawing."Journal of Trans- Compaction Characteristics of Soil Using portation Engineering,V. 126,No.5,Sept./Oct,pp.375-381. Standard Effort (12,400 ft-lbf/ft3 (600 Bell,F.G., 1993,Engineering Treatment of Soils,Taylor kN-m/m3)) and Francis,302 pp. D 1557 Standard Test Methods for Laboratory Bhayani, B.; Holsen, T. M.; and Neithalath, N., 2007, Compaction Characteristics of Soil Using "Investigations on the Efficiency of Enhanced Porosity Modified Effort (56,000 ft-lbf/ft3 (2,700 Concretes in Containing Vehicular Oil Spills,"Proceedings kN-nl in CD of the International Conference on Sustainability of D1883 Standard Test Method for CBR (California Construction Materials and Structures,Coventry,UK,8 pp. Bearing Ratio) of Laboratory-Compacted Brite/Euram Report, 1994, "Surface Properties of Soils Concrete Roads in Accordance with Traffic Safety and D2487 Standard Practice for Classification of Soils Reduction of Noise,"Brite/Euram Project BE3415, 138 pp. for Engineering Purposes (Unified Soil Crouch,L.K.;Cates,M.A.;Dotson,V.J.;Honeycutt,K.R.; Classification System) and Badoe,D. A.,2003,"Measuring the Effective Air Void Copyright American Conuete In"'mte American Concrete Institute Cc.,,.•;^6'^-'ea^'^-'^' ^ ^ •^^^-^ Prchded Oy IHS coder licensa wilh ACI �censee-CH2M HNI Worldwidev59604560a6.User.Troyan.Sean No reproduction or netwodeng permitted withoul license from IHS Not for Resale,01,28,2015 12 09.07 MST 38 REPORT ON PERVIOUS CONCRETE(ACI 522R•10) e Content of Portland Cement Pervious Pavements,"Cement, ington, DC, Nov., http://www.iccsafe.org/cs/igcc/pages/ Concrete and Aggregates,V.25,No. 1,pp. 16-20. default.aspx Crouch,L.K.;Smith,N.;Walker,A.C.;Dunn,T.R.;and Jing,Y.,and Guoliang,J.,2003,"Experimental Studies on Sparkman,A.,2006,"Deternuning Pervious PCC Permeability Properties of Pervious Concrete Pavement Materials," with a Simple Triaxial Flexible-Wall Constant Head Cement and Concrete Research,V.33,No.3,pp.381-386, Permeameter," TRB 85th Annual Meeting Compendium of Kevern, J.; Haselbach, L.-, and Schaefer, V., 2009, "Hot Papers, 18 pp. Weather Comparative Heat Balances in Pervious Concrete Das, B., 1993, Principles of Geotechnical Engineering, and Impervious Concrete Pavement Systems,"Proceedings: PWS Publishing Co.,Boston,MA,p. 146. The Second International Conference on Countermeasures Debo, T. N., and Reese, A. J., 2002, Municipal Storm to Urban Heat Islands,Sept.21-23,Berkeley,CA. Water Management,second edition,CRC Press,976 pp. Kevern, J. T., and Schaefer, V. R., 2008, "Temperature Delatte, N.; Miller, D.; and Mrkajic, A., 2007, "Field Response in a Pervious Concrete System Designed for Performance Investigation on Parking Lot and Roadway Stormwater Treatment," Proceedings of the American Pavements: Final Report," RMC Research & Education Society of Civil Engineers GeoCongress,New Orleans,LA, Foundation,79 pp. pp. 1137-1144. Deo, O.; Bhayani,B.; Holsen,T. M.; and Neithalath,N., Korhonen,C.J., and Bayer,J.J., 1989,"Porous Portland 2008,"Modeling the Retention of Oil in Enhanced Porosity Cement Concrete as an Airport Runway Overlay," Special Concretes," Proceedings of the NRMCA Concrete Tech- Report 89-12, U.S. Army Cold Regions Research and nology Forum,Denver,CO. Engineering Laboratory,Hanover,NH,20 pp, Erickson, S., 2006, "Pervious Concrete Durability Little,D. N.; Males, E. H.; Prusinski,J.R.; and Stewart, Testing," Technical Report, Viesko Quality Concrete, B., 2000, "Cementitious Stabilization, TRB Committee Salem,OR,6 pp. A2J01,"7 pp. Florida Concrete and Products Association(FCPA),1990, Low, K.; Harz, D.; and Neithalath, N., 2008, "Statistical Pervious Pavement Manual,Orlando,FL,57 pp. Characterization of the Pore Structure of Enhanced Porosity Ferguson,B. K., 1994,Stonnwater Infiltration,CRC Press, Concretes,"Proceedings of the NRMCA Concrete Technology 288 pp. Forum,Denver,CO. Ferguson, B. K., 1998, Introduction to Stormwater: Mahboub,K.;Canter,J.;Rathbone,R.;Robl,T.;and Davis, Concept, Purpose,Design,Wiley,272 pp. B.,2008,"The Effects of Compaction and Aggregate Gradation Ferguson, B. K., 2005, Porous Pavements, Taylor & on Pervious Concrete," Proceedings of the NRMCA Francis,New York,600 pp. Concrete Technology Forum,Denver,CO. Francis, A. M., 1965, "Early Concrete Buildings in Malhotra,V.M.,1969,"A Low-Cost Concrete Building," Britain," Concrete and Constructional Engineering, Engineering News Record,pp.62-63. London, ri 60 No.2,Feb., 73 Malhotra,V.M., 1976,"No-Fines Concrete-Its Properties Ghafoori,N.., 1995, "Development of No-Fines Concrete and Applications,"ACI JOURNAL,Proceedings V.73,No. 11, Pavement Applications,"Journal of Transportation Engi- Nov.,pp.628-644. veering,V. 126,No.3,May-June,pp.283-288. Haselbach,L.,2010,The Engineering Guide to LEED- Marolf,A.;Neithalath,N,;Sell,E.;Wegner,K.;Weiss,J.; New Construction: Sustainable Construction for Engi- and Olek,J.,2004,"Influence of Aggregate Gradation on the veers, Second Edition, McGraw-Hill Professional, New Acoustic Absorption of Enhanced Porosity Concrete,"ACI York,464 pp. Materials Journal,V. 101,No. 1,Jan.-Feb.,pp. 82-91. Haselbach, L.; Boyer, M.; Kevern, J.; and Schaefer, V., Mata, L., and Leming, M., 2008, "Sedimentation Effects 2011, "Cyclic Heat Island Impacts in Traditional Versus on Pervious Concrete," Proceedings of the 2008 National Pervious Concrete Pavement Systems," Transportation Ready Mixed Concrete Association Concrete Technology Research Record: Journal of the Transportation Research Forum,Denver,CO. Board,V.2240,pp. 107-115. Mathis, D. E., 1990, "Permeable Bases-An Update," Haselbach, L. M., and Freeman, R. M., 2006, "Vertical PCA,No.8,Nov.,pp.3-4. Porosity Distributions in Pervious Concrete Pavement,"ACI Maynard, D. P., 1970, "A No-Fines Road," Concrete Materials Journal,V. 103,No.6,Nov.-Dec.,pp.452-458. Construction,V. 15,No.3,pp. 116-117. Haselbach, L. M.; Valavala, S.; and Montes, F., 2006, Medico,J.J.,Jr„ 1975,"Porous Pavement,"U.S. Patent "Permeability Predictions for Sand Clogged Portland No. 3870422. Cement Pervious Concrete Pavement Systems,"Journal of Meininger,R.C., 1988,"No-Fines Pervious Concrete for Environmental Management,V.81,No. 1,pp.42-49. Paving,"Concrete International,V. 10,Aug.,pp.20-27, Herod, S., 1981, "Porous Concrete Market Blooms in Monahan, A., 1981, "Porous Portland Cement Concrete; Greenhouse,"Modern Concrete,Mar.,pp.40-44. the State of Art,"U.S.Army Engineer Waterways Experiment Houlsby,A.C.,1990,Construction and Design of Cement Station,Structures Laboratory,Vicksburg,MS.,Jan.,27 pp. Grouting,John Wiley and Sons,442 pp, Montes, F. and Haselbach, L. M., 2006, "Measuring ICC, 2010, "International Green Construction Code," Hydraulic Conductivity in Pervious Concrete," Environ- Public Version 2.0, International Code Council,..Wash- menial Engineering Science,Nov.,2006. Copyright American Concrete lnsdtule American Concrete Institute Co n h1^'I sa^a,^.:^I ........ Provided by IHS under license with ACI PY g Ucensee.CH2M Hil Worldwldei5960058046,User.Troi Sean No reproduction or networking permitted without license from IHS Not for Resale,0128/2015 12:09.07 MST REPORT ON PERVIOUS CONCRETE(ACI 522R-10) 39 Montes,F.;Valavala, S.; and Haselbach,L. M.,2005, "A Paine, J. E., 1990, "Stormwater Design Guide, Portland New Test Method for Porosity Measurements of Portland Cement Pervious Pavement,"Florida Concrete and Products 1 Cement Pervious Concrete,"Journal of ASTM International, Association,Orlando,FL, 13 pp. Jan.,V. 2,No. 1. Pindado,M.A.;Aguado,A.;and Josa,A., 1999,"Fatigue Mulligan, A., 2005, "Attainable Compressive Strength of Behavior of Polymer-Modified Porous Concretes," Cement Pervious Concrete Paving Systems," master's thesis, and Concrete Research,V. 29,No.7,pp. 1077-1083. 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Spring,MD, Feb.,60 pp. Rushton, B., 2000, "Low Impact Parking Lot Design Neithalath,N.,2004, "Development and Characterization Reduces Runoff and Pollutant Loads," Southwest Florida of Acoustically Efficient Cementitious Materials," PhD Water Management District,Brooksville,FL,225 pp. thesis,Purdue University,West Lafayette,IN,269 pp. Schaefer,V.R.;Wang,K.;Suleiman,M.T.; and Kevern, Neithalath, N.; Weiss, W. J.; and Olek, J., 2003, J. 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V Copyright American concrete Institute American Concrete Institute CoPyg U rl h''..I ^ Provided by IHS tinder Ikense with AM cersee•CH2M Hill Wor'dwlder5960456046.User.Troyan,Sean _ No reprodunior or networ"',ng permltfed without license from IHS Not tot Resale,01 2812015 1209.W MST s American Concrete Institute Advancing concrete knowledge As ACI begins its second century of advancing concrete knowledge, its original chartered purpose remains "to provide a comradeship in finding the best ways to do concrete work of all kinds and in spreading knowledge:' In keeping with this purpose, ACI supports the following activities: Technical committees that produce consensus reports, guides, specifications, and codes. Spring and fall conventions to facilitate the work of its committees. Educational seminars that disseminate reliable information on concrete. Certification programs for personnel employed within the concrete industry. 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