An Overview of Pervious Concrete Applications in Storm Water Management and Pavement Systems

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An Overview of Pervious Concrete Applications in Stormwater Management and

Pavement Systems

V.R. Schaefer1, M.T. Suleiman

2, K. Wang

3, J.T. Kevern

4and P. Wiegand

5

Abstract

Recent interest in the use of Portland Cement Pervious Concrete (PCPC) for pavements

has been very high, due primarily to the Federal Clean Water Act mandate that

government agencies and private entities manage stormwater runoffboth quantity andquality. Such pavements are full depth and are currently being placed primarily in

parking lot applications and areas of limited truck traffic. Pervious pavements provide a

path for water movement from pavement surfaces and provide increased skid resistance.In addition, PCPC has great potential to reduce roadway noise, either in full-depth

applications or as a wearing course. A PCPC mix design must meet the competing

criteria of sufficient permeability to allow water to flow through the section whilemaintaining adequate strength and durability under site-specific loading and

environmental conditions. To date, two key issues that have impeded the use of PCPC in

the United States are that compressive strengths of PCPC have been lower than necessaryfor required applications and the freeze-thaw durability of PCPC has been suspect. In

this paper a summary of recent research efforts on PCPC mix designs for cold weather

applications, reduction of road noise, stormwater management and constructability issues

is discussed. In addition, the efforts to develop a comprehensive and integrated study forfull depth and wearing course applications under the auspices of the National Concrete

Pavement Technology Center at Iowa State University are discussed.

Introduction

The Federal Clean Water Act mandate that government agencies and private entities

manage stormwater runoffboth quantity and qualityhas driven recent interest in the

use of Portland Cement Pervious Concrete (PCPC) use for pavements in the UnitedStates. This stormwater runoff interest in PCPC has been primarily in parking lot

applications and areas of limited truck traffic. In such applications the pavements are full

depth and provide a path for water to percolate through the pavement to an underlyingbase course or subgrade material, and ultimately to the underlying groundwater system or

a collection system. The need to either store the water or to provide movement to a

1

Professor, Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA, 50011,[email protected]

2Lecturer, Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA, 50011,

[email protected] Professor, Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA,

50011, [email protected] Assistant, Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA,

50011, [email protected], National Concrete Pavement Technology Center, Iowa State University, Ames, IA 50011,

[email protected]


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drainage and/or collection system necessitates a system approach to the design of thepavement system.

Overseas, primarily in Europe and Japan, PCPC has been used in highway pavementapplications to reduce noise and increase skid resistance. In such applications the PCPC

is often a wearing course, a few inches in thickness. Whether used in a full-depthpavement or a wearing-course application, a PCPC mix design must meet the competingcriteria of sufficient permeability to allow water to flow through the section while

maintaining adequate strength and durability under site-specific loading and

environmental conditions. Additionally, ancillary issues of system drainage and storage

must be addressed. To date, two key issues that have impeded the use of PCPC in theUnited States are that compressive strengths of PCPC have been lower than necessary for

required applications and the freeze-thaw durability of PCPC has been suspect.

There is great interest in PCPC for use in pavement applications for both stormwater

management and in highway applications such as noise reduction and skid resistance

purposes. This paper provides an overview of PCPC applications for stormwatermanagement and highway use. Recent research related to mix designs for cold weather

applications is discussed and research needs and issues related to PCPC use for

stormwater management, reduction of road noise, and constructability are touched upon.Increased use of PCPC pavements will provide benefits through improved stormwater

quality and management, and quieter and safer roadways. At present, additional

information is needed to allow designers to properly design full-depth and wearing courseoverlay PCPC pavement sections.

Applications

Pervious concrete pavement has been in use for several decades in various applications,ranging from minimizing runoff to improving irrigation to reducing roadway noise.PCPC has been used in parking lots, streets and local roads with minimal heavy truck

traffic. A wide range of PCPC applications is summarized in Table 1. With 15-20% air

voids, the pervious concrete pavement stays cooler and allows water to filter through to

replenish the water table. Pervious concrete pavements also help to reduce flash floods bytrapping storm-water runoff and help to improve water quality by filtering oil and

chemical pollutants. PCPCs ability to retain storm-water also has positive effects on plant

growth. By using pervious concrete, less land can be set aside for detention basins andirrigation requirements can be reduced. Numerous examples and pictures of applications

to stormwater management are available in recent literature (Tennis et al. 2004, Ferguson

2005, and others) and through internet searches and are thus not shown herein. PCPC has

widespread use in Europe and Japan for roadway applications as a surface course toimprove skid resistance and reduce traffic noise (Beeldens 2001 and Kajio et al. 1998).

The open-structure of pervious concrete pavement surfaces has three distinct advantages:the surface provides for reduced noise, reduced water spray, and enhanced skid resistance

in wet conditions. Road noise from pavements has become an increasingly important

issue in U.S. highway construction and the recent Concrete Pavement Roadmap identifies


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pervious concrete as a promising technology for developing safe, quiet and smoothconcrete pavements (Ferragut et al. 2005).

PCPC has been used as a surface layer on top of standard concrete pavement or as a full-depth pavement layer (Beeldens et al. 2003 and Ferguson 2005). At the present time the

focus in the U.S. is full-depth design for parking lots and low volume roads, whilesurface course designs are primarily used in Europe and Japan as a surface layer forroadways. Since PCPC does not necessarily behave like traditional PCC pavements,

empirical designs have dominated construction practices (Tennis et al. 2004). When used

as a surface layer on top of standard concrete pavement a 1.5 inch layer of PCPC placed

using a wet-on-wet method produced a good bond between the PCPC and PCC and adurable pavement (Beeldens et al. 2003). The wet-on-wet method places a thin layer of

fresh PCPC over a thicker layer of fresh normal concrete.

Table 1. PCPC Applications (after Tennis et al. 2004, Ferguson 2005 and others)

PCPC Applications

Low-volume pavements Residential roads, alleys, and driveways

Sidewalks and pathways Parking lots

Low water crossings Tennis courts

Subbase for conventional concrete

pavements

Foundations/floors for greenhouses, fish

hatcheries, aquatic centers, and zoos

Artificial reefs Slope stabilization

Well linings Tree grates in sidewalks

Patios Hydraulic structures

Pavement edge drains Groins and seawalls

Noise barriers Walls (including load-bearing)Concrete overlays for highway pavements Curb and gutter

Noise reduction Increased skid resistance

Hydroplaning reduction

Noise Reduction. The open structure of the pervious pavement causes a difference in

arrival time between direct and reflected sound waves as shown in Figure 1. Thisdifference causes the noise level to have a lower intensity causing pervious pavements to

absorb sound (Olek et al. 2003), which has drawn the interests of many researchers to

create quiet pavements (Kajio et al. 1998; and Olek et al. 2003). Kajio et al. (1998)

compared the noise levels produced from pervious concrete and dense asphalt pavementscontaining two different sizes of aggregate (i.e., 1/4-inch and -inch) at different vehicle

speeds and showed that for both sizes of aggregate the noise was reduced using perviousconcrete compared to asphalt. Small size aggregate generally produced a quieter

response ranging from 3% to 10% lower noise level, with a maximum difference of 8

decibels (dB).


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(a) (b)Figure 1. Reflection of sound waves resulting from moving vehicles, (a) Wave reflection

from a dense surface, (b) wave reflection from a porous surface (Oleket al.

2003)

Oleket al. (2003) measured noise reduction levels of PCPC using the Tire-Pavement TestApparatus (TPTA). PCPC was placed around a 12.1 feet diameter vertical drum. Once

cured a stationary vehicle tire contacts with the rotating drum. The tire is outfitted with

an array of microphones to determine the average noise value of the pavement. Three

mixes of PCPC were tested against three mixes of Portland cement concrete. Two of the

PCPC mixes were finished using a vibratory screed to smooth the surface and the otherwas allowed to have random surface aggregate orientation. Frequency was measured at

speeds of 10, 20, and 30 mph with as similar trend in frequency for each speed. As thefrequency increased the PCPC became quieter than the standard concrete pavement with

a maximum of 5 decibels (dB) (Oleket al. 2003).

Advantages of Portland Cement Pervious Concrete

In stormwater management applications the key advantage that PCPC has is that of

allowing surface water to easily flow through the pavement structure. The relative highpermeability (often in the 100s of inches per hour) provides for almost complete

percolation of surface water into the pavement, with little to no resulting runoff from the

pavement surfaces. This ability to reduce peak runoff from storm events and reduction instorage detention basins are key uses driving the high interest in PCPC applications. Thecaveat in such applications is that the underlying base course and/or the subsurface soils

must have sufficient permeability to handle the water flow through the pavement

structure. Additionally, the filtering action of the pervious concrete provides someparticulate and contaminate removal from stormwater.

Other advantages are reduction of splash, prevention of ice formation on pavementsurface, reduction of roadway noise, less absorption and storage of heatcooler

pavements, and increased skid resistance. The surface characteristics of PCPC have great

potential in highway applications, in both full depth and wearing course (overlay)

applications.

Challenges of Portland Cement Pervious Concrete

While PCPC has seen tremendous growth in use recently, primarily in the southernUnited States, challenges remain. A number of failures have occurred in use of PCPC,

thus presenting challenges to its use. Among the key challenges are strength and

durability issues, maintenancemost importantly clogging, constructability issues,


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restrictions on heavy vehicles, and cost. Premature failures that affected the industry canoften be linked to a substandard mix designthe mixes were deficient in the amount of

cementitious materials in the mix. Additionally, the use of PCPC in northern climates

was hindered by the lack of a viable freeze-thaw resistant mix design. Hence,overcoming these challenges necessitates rational approaches to development of design,

construction, and maintenance strategies.

Design. In the design area a systems approach is necessary in which the entire pavement

section in considered as a whole. This is true whether one is considering full depth or

wearing course applications. In Figure 2 is shown an idealized section of a PCPC

system. The PCPC pavement layer is just one part of the entire system, albeit a veryimportant part, and is discussed more fully later. Below the pavement layer is the

reservoir system, which may have several pieces including filter layers at the top and

bottom of the reservoir layer. The reservoir system may be sized to store and retain givendesign storm events or may simply act as a conduit for the water to flow to the underlying

soils or to be move out through drainage pipes. Thus hydrologic considerations play a

key role in the system design through the reservoir system, and are more fully developedin Tennis et al. (2004) and Ferguson (2005). The subgrade underlies the reservoir

section, and may be separated by a geofabric layer. Not all of these layers/parts are

present in most applications, but each serves a function in such an idealized section.

Figure 2. Idealized cross section of a PCPC pavement section, NTS.

Proportioning of the mix design plays a key role in the success of any concrete pavementand PCPC is no different. Recently, the authors completed a study of mix designs

primarily for freeze-thaw resistance (Schaefer et al. 2006), with preliminary resultsreported in Kevern et al. (2005) and additional results reported in companion papers to

this conference, Wang et al. (2006) and Suleiman et al. (2006). The key findings of this

work can be seen in Figure 3, which shows the relationship between 7-day compressivestrength, void ratio and permeability of several trial mixes. From Figure 3 it can be seen

that as the void ratio changes, strength and permeability change in an inverse relationship

PCPC LayerFilter Layer

Base Course

Reservoir

Filter LayerFilter Fabric

Subsoil


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to one another. As shown by the dashed lines, void ratios between 15 and 20% providesa range in which the strength is above 3000 psi and the permeability remains several

hundred inches per hour. Additionally, freeze-thaw test results on several trial mixes

resulted in a mix design which is resistant to some 300, completely saturated, freeze-thawcycles. Clearly additional work remains to be conducted on developing mix designs to be

durable for a variety of conditions.

Void ratio (%)

5 10 15 20 25 30 35 40 45

7-daycompr

essivestrength(psi)

0

500

1000

1500

2000

2500

3000

3500

4000

Permeability(in./

hour)

0

500

1000

1500

2000

2500

Strength

Permeability

Permeability (in./hour) = 15.93 (Void Ratio)0.1445

Strength(psi) = 4316-85*(Void Ratio)

Figure 3. Relationship between strength, void ratio and permeability for several trial

mixes of PCPC.

Construction. At the present time, the construction of PCPC systems remains quite

labor intensive due to the viscous nature of the mixes. Past and present construction

practices are discussed in more detail in the companion paper to this conference byKevern et al. (2006). Construction practices are key emerging issues in the future use of

PCPC in both full depth and wearing course applications. To become more cost effective

and to allow large projects and highway applications to be constructed, mechanized

placement and finishing will be required. Several manufacturers are working to developsuch machinery. For overlay applications two lift paving machinery holds great promise.

Maintenance. The overriding maintenance issue in PCPC pavements is that ofclogging. There has been much discussion and concern about the clogging of pervious

concrete pavement sections, with much of it conflicting. Reports abound of clogged

pavements that do not allow water to pass. At the same time there are reports of perviouspavements along the beaches of Florida which are unaffected by the abundant sand

washed onto the surfaces. Due to the high permeability of PCPC, much small sized

material will pass through the concrete section. The clogging and unclogging of PCPC


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sections needs further study. In northern climates, consideration of potential damage tothe concrete surface due to snow removal operations may be of concern.

Comprehensive and Integrated Study of Pervious Concrete

The National Concrete Pavement Technology Center at Iowa State University is currently

developing a research program aimed at developing PCPC mix designs for both fulldepth sections and wearing course sections in pavement applications. There isconsiderable overlap in the information needed for both full-depth and wearing course

sections; however, there will be some information specific to each also. For the full

depth sections strength, durability, and environmental issues will be of paramount

importance and for the wearing course sections the issues of noise and skid resistancewill predominate (assuming adequate strength and water movement capacities). The

constructability issues may also be different for the two sections. At present the

construction of full depth sections is quite labor intensive. It is of paramount importancefor the research to determine techniques for construction that utilizes existing pavement

equipment. The use of PCPC as a wearing course entails construction of a concrete

overlay in rehabilitation efforts. In new construction two-lift construction is a possibility.Thus a two-track research program is envisioned, one track focused on full-depth sections

and one track on wearing course sections. Where possible information will be

interchanged between the two tracks; for example, mix design strength and permeabilityrequirements for the two applications will be similar. A comprehensive study will

require many partners to study the many facets of PCPC pavements.

Common to Both Tracks. Studies on mix designs providing adequate strength, voidratio, permeability, durability and constructability will be common to both full-depth

pavement sections and wearing-course sections. Such studies need to consider various

aggregate types and mix proportions used across the United States and determine the

basic requirements for aggregate quality, aggregate gradation, concrete and admixtureproportions to produce the proper strength, porosity, permeability and freeze-thawresistance of PCPC. Recent studies at Iowa State University have indicated that

compaction methods can have significant effects on the resulting properties of PCPC, see

the companion paper to this conference by Suleiman et al. (2006).

Full Depth Pavement Track. In addition to mix design considerations, placement

techniques and design thicknesses for various applications will need to be studied anddeveloped. At the present time the placement of PCPC in parking lot applications is

particularly labor intensive. To see expanded use, improved construction techniques that

reduce labor and/or make use of existing or new construction machinery will need to be

developed. Design thickness requirements for parking lot applications under variousconditions and for highway applications will need to be evaluated and determined.

Expected outcomes are energy requirements for proper PCPC and the relationship

between compaction and porosity, strength, and permeability, recommended sitecompaction and construction methods, recommended PCPC thickness designs for full-

depth pavement sections, the effect of clogging on PCPC properties, and construction

techniques that utilize existing equipment.


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Much of the mix design efforts will be in laboratory trials. Field trial sections will needto be constructed to evaluate in-place PCPC properties and the effects of construction

methods on the in-place properties. Expected outcomes will be correlations between

field concrete properties and laboratory test results, evaluation of the durability of PCPCunder various environmental conditions in field use, the effectiveness of maintenance on

performance (particularly permeability), and the effectiveness of PCPC with respect tonoise and skid resistance.

Particular to the full-depth track for parking lot and similar applications is the evaluation

of drainage, water quality and freeze-thaw resistance of PCPC pavement systems.

Investigation and evaluation of the water purification abilities of PCPC systems,including the pavement section, the base and the subgrade, will be necessary in both

laboratory and field trials. The effectiveness of various drainage systems with PCPC in

laboratory trials using scaled models and in field trials will be necessary. Expectedoutcomes include the minimum porosity and permeability required for the base and

subgrade layers to provide sufficient drainage for given design storms, the effectiveness

of PCPC systems in water purification, optimum system design for the PCPC system toachieve multiple objectives, and an understanding of the behavior of PCPC systems in

frozen conditions.

Wearing Course Pavement Track. Key issues related to overlay and wearing coursesections is evaluation of noise and skid resistance in the laboratory and the field;

determination and evaluation of wearing course thickness design, constructability, and

longevity; and field trials of promising sections.

A recent study at Purdue University (Olek et al. 2003) has shown that PCPC (termedenhanced porosity concrete in the Purdue University study) can reduce tire-pavement

interaction noise. Tests conducted in Purdue Universitys Tire-Pavement Test Apparatus

(TPTA) showed reduced noise levels above 1000 Hz and some increase in noise levelsbelow 1000 Hz. The increased porosity of PCPC increased mechanical excitation and

interaction between the tire and pavement at frequencies below about 1000 Hz and at

frequencies above about 1000 Hz, the air pumping mechanics that dominate at suchfrequencies are relieved by the increased porosity leading to decreased high frequency

noise levels. Several PCPC pavements have been constructed in Europe and PCPC has

been shown to be promising in reducing tire-pavement noise and wet weather spray

(Descornet et al. 1993; Gerharz 1999). Expected outcomes of studies on noise and skidresistance include the minimum porosity and permeability required for surface

characteristic enhancement, the effectiveness of PCPC systems in noise and skid

resistance, PCPC mix designs for optimal surface characteristic properties, correlationsbetween laboratory concrete properties and surface characteristic measures, evaluation of

clogging and its effect on surface characteristic performance.

Investigation and evaluation of the necessary thickness and construction methods needed

to provide sufficient strength and environmental properties for use of PCPC as an overlay

wearing course or constructed as a two-lift concrete will be needed. Overlay applicationswill require evaluation of the bonding between overlay PCPC and underlying concrete


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and appropriate methods of water removal for overlayed PCPC layers. Expectedoutcomes will be design thickness requirements for PCPC wearing course layers,

drainage requirements for PCPC wearing course layers, and recommended construction

methods for PCPC wearing course overlays or two-lift construction. Suchrecommendations will need to be studied and evaluated in field trial sections that

examine the surface characteristics, the constructability, and the structural andenvironmental performance of in-place PCPC pavement sections.

Summary

A review has been provided of recent interest in the use of Portland Cement Pervious

Concrete (PCPC) for pavements for stormwater management and wearing courseapplications. The advantages of PCPC in such applications have been discussed and the

challenges facing PCPC use from design, constructability and maintenance points of view

have been elaborated upon. Results of recent work at Iowa State University in mixdesign development and related freeze-thaw durability was reviewed. Finally, a research

program aimed at a comprehensive and integrated study of the factors affecting the use of

PCPC in full-depth and wearing course applications was outlined and discussed.

References

Beeldens, A,. Van Gemert, D., and Caestecker, C. (2003). Porous Concrete: LaboratoryVersus Field Experience. Proceedings 9th International Symposium on ConcreteRoads, Istanbul, Turkey.

Beeldens, A. (2001). Behavior of Porous PCC Under Freeze-Thaw Cycling. The Tenth

International Congress on Polymers in Concrete, Honolulu.

Ferragut, T.R., Harrington, D. and Brink, M. (2005). Long-term Plan for ConcretePavement Research and TechnologyThe Concrete Pavement Road Map: Volume

I, Background and Summary. Office of Infrastructure Research and Development,Federal Highway Administration, Report No. FHWA-HRT-05-052, September, 119pp.

Descornet, G., Fuchs, F. and Buys, R. (1993). Noise reducing concrete pavements.

Proceedings of the Fifth International Conference on Concrete Pavements and

Rehabilitation, Purdue University, Vol. 2, pp. 93-98.

Gerharz, B. (1999). Pavements on the base of polymer-modiifed drainage concrete.

Colloids and Surfaces A: Physiochemical and Engineering Aspects, Vol. 152, pp.

205-209.

Ferguson, B. K. (2005). Porous Pavements. Taylor and Francis Group. New York. New

York.

Olek, J., Weiss, W.J., Neithalath, N., Marolf, A., Sell, E. and Thornton, W.D. (2003).

Development of quiet and durable porous Portland cement concrete paving

materials. Final Report SQDH 2003-5, Purdue University, September, 172 pp.

Kajio, S., Tanaka, S., Tomita, R., Noda, E., and Hashimoto, S. (1998). Properties of

Porous Concrete with High Strength. Proceedings 8th International Symposium

on Concrete Roads, Lisbon, pp. 171-177.


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Kevern, J., Wang, K., Suleiman, M.T. and Schaefer, V.R. (2005). Mix designdevelopment for pervious concrete in cold weather climates. Proceedings of the

2005 Mid-Continent Transportation Research Symposium, Ames, Iowa, August, on

CD-Rom.

Kevern, J., Wang, K., Suleiman, M. T., and Schaefer, V. R. (2006). Pervious Concrete

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Nashville, TN, May 23-25.

Schaefer, V.R., Wang, K., Kevern, J., Suleiman, M.T. (2006). Mix DesignDevelopment for Pervious ConcreteIn Cold Weather Climates. Research Report,

Center for Transportation Research and Education, Iowa State University, Ames,

Iowa.

Suleiman, M. T., Kevern, J., Schaefer, V. R., and Wang, K. (2006). Effect ofCompaction Energy on Pervious Concrete Properties. Submitted to Concrete

Technology Forum-Focus on Pervious Concrete, National Ready Mix Concrete

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Tennis, P.D., Leming, M.L., and Akers, D.J. (2004). Pervious Concrete Pavements,Special Publication by the Portland Cement Association and the National Ready

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Documents

An Overview of Pervious Concrete Applications in Storm Water Management and Pavement Systems