Pervious concrete pavement is a unique and effective means to address important environmental issues and support green, sustainable growth. By capturing storm water and allowing it to seep into the ground, porous concrete is instrumental in recharging groundwater, reducing storm water runoff, and meeting U.S. Environmental Protection Agency (EPA) stormwater regulations. In fact, the use of pervious concrete is among the Best Management Practices (BMPs) recommended by the EPA-- and by other agencies and geotechnical engineers across the country-- for the management of stormwater runoff on a regional and local basis. This pavement technology creates more efficient land use by eliminating the need for retention ponds, swales, and other storm water management devices. In doing so, pervious concrete has the ability to lower overall project costs on a first-cost basis.
In pervious concrete, carefully controlled amounts of water and cementitious materials are used to create a paste that forms a thick coating around aggregate particles. A pervious concrete mixture contains little or no sand, creating a substantial void content. Using sufficient paste to coat and bind the aggregate particles together creates a system of highly permeable, interconnected voids that drains quickly. Typically, between 15% and 25% voids are achieved in the hardened concrete, and flow rates for water through pervious concrete are typically around 480 in./hr (0.34 cm/s, which is 5 gal/ft²/ min or 200 L/m²/min), although they can be much higher. Both the low mortar content and high porosity also reduce strength compared to conventional concrete mixtures, but sufficient strength for many applications is readily achieved.
While pervious concrete can be used for a surprising number of applications, its primary use is in pavement. This site focuses on the pavement applications of the material, which also has been referred to as porous concrete, permeable concrete, no-fines concrete, gap-graded concrete, and enhanced-porosity concrete.
Volumetric mixers are an ideal way to deliver pervious concrete as one of the original demonstrations for the mega demo at the World of Concrete was done with a Cemen Tech volumetric mixer. The ability to have the concrete on demand in the precise mix and exact slump play a huge role in providing quality pervious concrete.
The market continues to expand as does the need for pervious concrete. Pervious concrete is considered by many to be environmentally friendly because of its application. A huge advantage for volumetric mixers is that they are also environmentally friendly and a good selling point for those who wish to enter this market.