Permeable Concrete

Pervious concrete is a special type of concrete with a high porosity used for concrete flatwork applications that allows water from precipitation and other sources to pass through it, thereby reducing the runoff from a site and recharging groundwater levels. The high porosity is attained by a highly interconnected void content. Typically, pervious concrete has little to no fine aggregate and has just enough cementitious paste to coat the coarse aggregate particles while preserving the interconnectivity of the voids.?

Pervious concrete is traditionally used in parking areas, areas with light traffic, pedestrian walkways, and greenhouses. It is considered one of the important applications for sustainable construction.

Usually, pervious concrete is designed to achieve (3 to 10 MPa) compressive strength, however, pervious concrete is not specified or accepted based on strength. Acceptance is typically based on the density of the in-place pavement which varies (±80Kg/m3).

As with any concrete pavement, proper subgrade preparation is important. The subgrade should be properly compacted to provide a uniform and stable surface. It is recommended to compact the subgrade before pervious concrete is placed.

Typically, pervious concrete has a water to cementitious ratio (W/C) of 0.35 to 0.45 with a void content extended to 30%. The mixture is composed of cement, coarse aggregate, and water with little to no fine aggregate.?

Because the mixture contains little or no sand with the presence of low water content. Unfortunately, this lack of sand results in a very harsh mix that negatively affects missing, delivery and placement.? Mapei has developed a typical solution to enhance the production, handling, and placement of pervious concrete. This system is developed to help producers and contractors overcome these issues.

MAPEPLAST RP100 acts as a cement dispersant, allowing water reduction and efficient cement hydration to maximize the strength of pervious mixes.

VISCOSTAR 3K: since pervious concrete is a harsh mix, Viscostar 3K, a viscosity–modifying admixture, adds body and helps lubricate the mixes. The result is better flow and faster discharge time from the truck and easier placement and compaction in addition that it helps prevent past drain down while casting.