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Applications  > Pervious Paving
Cast-in-place allows water to pass through
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Pervious concrete is made from carefully controlled amounts of water and cementitious materials used to create a paste that forms a thick coating around aggregate particles. Unlike conventional concrete, the mixture contains little or no sand, creating a substantial void content – between 15% to 25%.

Using sufficient paste to coat and bind the aggregate particles together creates a system of highly permeable, interconnected voids which drain quickly. Both the low mortar content and the high porosity reduce strength compared to conventional concrete, but sufficient strength is readily achieved for many applications.

Pervious concrete allows 3 to 8 gallons of water per minute to pass through each square foot of the material. By allowing rainwater to seep into the ground, pervious concrete can be instrumental in recharging groundwater and reducing stormwater runoff. This capability can reduce the need for retention ponds, swales, and other stormwater management devices. Pervious pavement integrates hardscape surfaces with stormwater management.
uses

 

sustainabilityApplications for pervious concrete include:
Hardscape
Low-volume pavements
Residential roads, alleys, and driveways
Low-water crossings
Parking lots
Sidewalks and pathways
Patios
Tennis courts
Swimming pool decks
Pavement edge drains
 
Floors
Foundations/floors for greenhouses, fish hatcheries, aquatic amusement centers, and zoos
 
Walls
Load bearing and other walls
Sound barriers
Other
Subbase for conventional concrete pavement
Slope stabilization
Artificial reefs
Well linings
Hydraulic structures
Tree grates in sidewalks
Groins and seawalls
why

Use of pervious concrete is among the Best Management Practices (BMP) recommended by the EPA and other agencies for the management of stormwater runoff on a regional and local basis. By eliminating the need for retention ponds, swales, and other stormwater devices, pervious concrete can lower overall project costs on a first-cost basis, and makes more efficient use of the land. Pervious concrete can also reduce operational costs and allow developers to increase utilization of available property. Pervious concrete has a significantly lower life cycle cost than other alternatives and saves money in teh long run due to its superior durability, strength, and long life span. Parking lot owners who use pervious spend fewer dollars on stormwater management systems and irrigation systems may be downsized or eliminated. Pervious canhelp property owners minimize sewer system usage and avoid municipal stormwater impact fees.
sustainability

 

Pervious concrete has many environmental benefits. See associated sustainability solutions and technical briefs (right) for more detail.
 
Stormwater Management. By allowing water to soak through and infiltrate, pervious paving reduces stormwater flow and pollutant loads. Can contribute to LEED Credit 6.
 
Minimize Site Distrubance. By integrating paving and drainage, less site area may need to be used to manage stormwater, allowing a more compact site development footprint. May contribute to LEED Credit SS 5.
Local. Materials are usually extracted and manufactured locally. May contribute to LEED Credit M 5.
Recycled content. Fly ash, slag cement, or silica fume can substitute partially for cement, and recycled aggregates can replace newly mined gravel. Recycled content can contribute to LEED Credit M 4.
Cool. The voids reduce mass reducing the heat build up associated with heat islands. Lighter colored cements can increase reflectivity. Not specifically approved for achieving LEED Credit SS 7.
considerations

Pervious concrete after screeding (left) and after compaction (right). Note the joint aligned with previously placed slab to avoid reflective cracking. Roller used for compaction is visible on the far right. (Photo courtesy of B. Banka, PCA No. 15592)The properties of pervious concrete vary with design and depend on the materials used and the compaction procedures. General guidelines for specifications are provided below.

Permeability. Typical flow rates for water through pervious concrete are 3 to 8 gallons per sq foot per minute, but can be double that amount if desired.

Compressive Strength. Pervious concretes can develop compressive strengths in the range of 500 to 4000 psi – suitable for a wide range of applications.

Flexural Strength. Flexural strength of pervious concrete ranges between 150 and 550 psi.

Shrinkage. Drying shrinkage of pervious concrete is faster but much less than that experienced with conventional concrete. Many pervious concretes are made without control joints and are allowed to crack randomly.

Freeze-Thaw Resistance. Freeze-thaw resistance depends on the saturation level of the voids in the concrete at the time of freezing. In the field, it appears that the rapid draining characteristics of pervious concrete prevent saturation from occurring. Where substantial moisture and freeze-thaw conditions are anticipated, pervious concrete should be placed on a 6 to 18-in.-thick layer of drainable rock base such as 1-in. crushed stone.

Abrasion resistance. Because of the rougher surface texture and open structure of pervious concrete, abrasion and raveling of aggregate particles can be a problem, particularly where snowplows are used to clear pavements. Surface raveling in new pervious concrete can occur when rocks loosely bound to the surface pop out under traffic loads. This raveling is considerably reduced after the first few weeks.


BOOKMARK
Resources
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 Pervious Concrete
Concrete Technology, August, 2007
A properly designed pervious concrete pavement system can reduce the environmental impact often associated with development. This overview discusses the hydrologic design of pervious concrete, both passive and active mitigation systems and the important consideration in design for storms. The article includes a link to a publication on pervious paving design as well.
Located at BookstorePervious Concrete Pavements (2004)
Paul D. Tennis, Michael L. Leming, and David J. Akers, Portland Cement Association, Item Code EB302, 36 pages
Available for $25. Pervious concrete as a paving material has seen renewed interest due to its ability to allow water to flow through itself to recharge groundwater and minimize stormwater runoff. This introduction to pervious concrete pavements reviews its applications and engineering properties, including environmental benefits, structural properties, and durability. Both hydraulic and structural design of pervious concrete pavements are discussed, as well as construction techniques.
Located at BookstorePervious Concrete: Solutions to Stormwater Runoff
National Ready Mixed Concrete Association, #CES 003, 1 hour
Available for $29 member, $49 non-member. This online seminar provides an introduction to pervious concrete pavement as a solution to reducing stormwater runoff from building sites. The seminar is 1 hour (1 PDH).
Located at BookstorePorous Pavements (2005)
B. K. Ferguson, Portland Cement Association, Item Code: LT 291, 557 pages
Available for $160. This text book on pervious pavement technology covers concrete, asphalt, paving blocks, and others. With its clear explanation and evaluation of each type, it allows landscape architects, civil engineers, and contractors to review and choose materials to meet site-specific conditions. Installation methods, performance levels, and appropriate applications are all addressed. Numerous case studies are included.
Download DocumentConcrete in Practice No. 38 - Pervious Concrete (2004)
National Ready Mixed Concrete Association, 2 pages.
Available for free. Concrete In Practice-Pervious Concrete is a one-page information sheets on important technical topics, written in a non-technical "What, Why and How?" format.
Download DocumentFreeze Thaw Resistance of Pervious Concrete (2004)
National Ready Mixed Concrete Association, 17 pages
Available for free. There have been several pervious concrete pavement projects in dry and wet freeze areas demonstrating good field performance over several years. Recommendations for successful performance of pervious concrete pavements under the various freeze-thaw conditions have been provided. There is limited experience of performance of pervious concrete pavements in hard wet freeze areas. Therefore, in such areas utmost care must be taken. Pervious pavements should be placed by an experienced installer and the pavement structure and surrounding details should be designed to accommodate the anticipated water flow and drainage requirements.
Download DocumentNorth Carolina State University Evaluates Permeable Pavements (2006)
David R. Smith, Kelly A. Collins and William F. Hunt, III, Interlocking Concrete Pavement Magazine, November 2006
The Biological and Agricultural Engineering Department at North Carolina State University is taking a second look at permeable pavements at a test site in Kinston, NC. The project evaluates runoff from four types of permeable pavement and asphalt. Preliminary results show substantial runoff volume and peak flow reductions, the verdict is expected to confirm the effectiveness of permeable pavements in water quality improvement.
Download DocumentPervious Concrete - When It Rains, It Drains
National Ready Mixed Concrete Association, 4 pages
Available for free. This brochure provides an overview of the features and benefits of site cast pervious pavement, as well as an FAQ and additional resources for information.
Download DocumentPervious Concrete Mixtures and Properties (2004)
Portland Cement Association, CT043, 8 pages
Available for free. Pervious concrete is ideally suited as a solution to stormwater management issues with added environmental benefits. The large void content designed into this specialty concrete allows water to pass through rapidly, minimizing runoff and recharging groundwater supplies. Also known as permeable concrete, porous concrete, gap-graded concrete, no-fines concrete, and enhanced porosity concrete, pervious concrete can be used in a wide range of applications, although its primary use is in pavements.
Download DocumentPervious Concrete Pavement: A Win-Win System (2003)
Dan Brown, P.E., Portland Cement Association, CT032, 9 pages
Available for free. Use of Pervious Concrete Pavements Helps Owners and the Environment.
Download DocumentUnderstanding Pervious Concrete (2005)
Dan Huffman, Construction Specifier Institute, December 2005, 9 pages
Available for free. While pervious concrete pavement has been around for more than 20 years, it has only recently garnered much attention due to increasingly stringent stormwater management guidelines that now position the product as a sustainable building material. Pervious concrete provides the potential for environmentally responsible site use and lowered construction costs in projects ranging from a simple sidewalks, driveways and patios, to major pedestrian plazas and full-blown multi-acre parking lots for national commercial big box builders.
Located at External Web SiteChanges In Store (2006)
Wal-Mart showcases green concrete technologies at its store in Texas.
This 4 page article was originally featured in the May 2006 edition of Concrete Producer Magazine, by Hanley Wood. Wal-Mart testing a range of green strategies at this prototype store in McKinney, TX. Along with other green strategies, concrete was used as interior finish flooring, reducing VOC's and maintenance, and pervious pavement in the parking area to improve ground water quality and quantity.
Located at External Web SiteSedimentation of Pervious Concrete Pavement Systems
Pervious concrete pavement systems (PCPS) are a unique and effective means to address important environmental issues and support green, sustainable growth, by capturing stormwater and allowing it to infiltrate into the underlying soil. Sedimentation leading to clogging is a potential problem in serviceability of PCPS.