Pervious concrete is concrete that water drains right through.
Usually pervious concrete consists of rock, cement & water, everything regular concrete has, minus the sand. [more]
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Specify and install PrettyPervious™ to see how fine and consistent pervious concrete can be. We invested over 6 years testing and tweeking our mix design and installation techniques for PrettyPervious™, which is a topping that goes over standard pervious concrete. PrettyPervious™ is available in individual 50 lb sacks as well as in larger bulk quantities for commercial or municipal projects.
Specify PrettyPervious™ concrete on your next job anywhere in the continental United States and let us help you bring beautiful, successful pervious concrete to your area. Please contact Ryan Marlinghaus directly for more information: 408 529-8571.
- Environmental responsibility: green building movement - market forces/pr-LEED (see below)
- Stormwater regulations: US EPA NPDES phase II
- Favorable cost factors: Pervious concrete can be the least expensive stromwater management practice to implement overall on a project.
“Urban storm water runoff is the predominant cause of water quality decline and erosion/sedimentation of streams, lakes and bays.1
And in Buid It Green's Green Point Rated single family checklist:
In section P. INNOVATION A. Site 1 & 2 the use of pervious concrete can achieve 3 points
EPA’s Phase II Program
US Cleanwater Act – NPDES - National Pollutant Discharge Elimination System
US EPA’s phase II program requires min. 6 control measures:
Education & outreach
Illicit discharge detection & elimination
Construction Site Stormwater Runoff Control
Pollution prevention for municipal operations
Post-Construction Stormwater Management – new development & redevelopment
1 acre or more
On-site stormwater treatment before discharge from site
EPA offers a list of Best Management Practices(BMPs) to help owners within regulated areas to control runoff. The effective use of porous pavements are an approved BMP for compliance with phase II stormwater regulations.
Note: The State Water Resources Control Board through the regional water boards is responsible for administering the NPDES program in the state of California. For the San Francisco Bay Watershed the regional water board responsible for administering this requirement is the San Francisco Bay Regional Water Quality Control Board.
Energy Independence & Security Act of 2007 – signed into federal law 12-19-07
SEC.438 STORMWATER RUNOFF REQUIREMENTS FOR FEDERAL DEVELOPMENT PROJECTS
“The sponsor of any development or redevelopment project involving a Federal facility with a footprint that exceeds 5000 square feet shall use site planning, design, construction, and maintenance strategies for the property to maintain or restore to the maximum extent technically feasible, the predevelopment hydrology of the property with regard to the temperature, rate, volume and duration of flow.”
EarthCare's PrettyPervious™ pervious concrete is typically less expensive than installing standard interlocking pavers. Incorporating the use of more colors or more involved designs may increase installation costs to around the cost of installing pervious pavers, but without the associated maintenance issues.
Pervious Concrete Repair:
Pervious concrete that is failing due to raveling can be repaired with a durable finish that will last for years. In addition the 'repaired' pervious concrete will now look far superior to what the original was supposed to look like with the use of our PrettyPervious™. Generally all the design and color options of PrettyPervious™ our available for this application.
Additional Benefits of Pervious Concrete:
Studies conducted by the American National Standard Unit(ANSI) show that light-colored pavements, such as concrete, can be 50% more light reflective than dark-colored pavements. This means that a lot less energy may be needed to illuminate pavement areas at night. It also means money can be saved, both initially by using lesser fixtures and saving about $1 per square foot and annually from $.05 to $.10 per square foot.
Additional Facts About Pervious Concrete:
Pervious concrete can not be pumped. However that doesn't mean large amounts of it can't be placed very quickly & efficiently. Tractors can be used instead, but typically in larger placements, a telebelt system is used - a little more expensive, larger piece of equipment than a pump, but just as effective.
Be very careful who you have to your pervious concrete work. Both the installer and the supplier of the pervious concrete need to have experience with this material as it can be very tricky to work with. Pervious concrete is not like regular concrete.
The primary reason pervious concrete is so difficult to work with is because of its very narrow water demand, a little too much water and the surface can become impervious and too little water or improper curing can cause the surface to fail in the form of raveling. Raveling is basically the surface rocks becoming loose.
Pervious concrete can be painted and even concrete sealers can be applied to it. An advantage to our PrettyPervious™ is that the lines of a parking lot and handicap insignias can be integrally colored, therefore saving having to paint these areas every two to three years as is typical.
There are currently two ASTM approved tests for pervious concrete: ASTM C1688, the unit weight test and ASTM C1701, the permeability test.
There is a widespread perception that pervious concrete needs to be 'wet-cured'. Typically this is done by immediately, within 20 minutes of placement, covering the pervious concrete with a heavy plastic and then kept that way for at least 7 days(10 days for fly ash-modified mixes). Wet-curing may in fact increase the final compressive strength of pervious concrete somewhat just as it would when implemented on regular concrete, however it is not a guarantee against raveling (loosening of the surface rocks). The downside to this type of 'wet-curing' is the efflorescence and 'tiger-striping' it causes. Efflorescence, a white residue, and lines are usually apparent when the plastic is removed. Though this can be a temporary condition that goes away after a year or two, we find it unacceptable for our residential clients and our often very colorful mixes. We therefore have developed our own mix designs and installation practices, that eliminate the use of plastic and its unsightly side affects.
Pervious concrete can be installed with costs comparable to asphalt in certain situations. In particular for pedestrian paths a slipform paver such as one manufactured by Evolution Paving in Salem Oregon can be utilized. A local example of this application is the 1/2 mile path from McClellan Ranch to Blackberry Farm in Cupertino.
Approximately 500,000 square feet of pervious concrete were placed in CA in 2007. In 2008 it was in the millions!
Damage to pervious concrete due to weakening of the subgrade by allowing all that water to reach it is generally not an issue, because the enitire subgrade is getting wet at the same time. The means the soils underneath generally expand and contract together.
Another Word In Regards to the Strength of Pervious Concrete:
Even though pervious concrete is a little weaker than regular concrete, how strong do pavements need to be? Conservatively our pervious concrete mix designs range in compressive strength from 2000 to 3000 psi, but we can design the strength for whatever your requirements may be. Now according to the calculations from http://www.csgc.ucsd.edu/BOOKSTORE/Resources/LID_FACTSHEET.pdf there is a seven-fold safety factor for even firetrucks on a typically designed pervious concrete street.
1 (Arnolds & Gibbons, 1996; US EPA 1996)
More technical definition of pervious concrete from the NRMCA (National Ready Mix Concrete Association)
“Pervious Concrete (PC) is a performance engineered pavement with an interconnected void system that allows rainwater to percolate through it. In PC, carefully controlled amounts of water and cementitious materials are used to create a paste that forms a thick coating around aggregate particles.
A PC mixture contains little or no sand. Using sufficient paste to coat and bind the aggregate particles together creates a system of highly permeable, interconnected voids that drain quickly.
Typically, between 15% and 25% voids are achieved in the hardened concrete, and flow rates for water through PC are typically around 480 in/hr (.34cm/s), which is 5 gal/sqft/min (200L/sqm/min) or higher.
Although low mortar content and high porosity reduce strength compared to conventional concrete mixtures, PC has sufficient strength for most pavement applications including parking areas, streets, plazas, and walkways.”