Optimal Mix Designs for Pervious Concrete for an Urban Area

Abstract

Pervious concrete is mixture of cement, aggregate, and water that provide a level of porosity which allows water to percolate into the sub-grade. It differs from the conventional concrete since it usually contains a smaller amount of fine aggregate. There is typically single size aggregate in pervious concrete which provides larger air void than conventional concrete to increase the rate of infiltration. Most jurisdictions have different pervious concrete mix designs. This research was aimed at developing and testing five design mixes of pervious concrete to identify the appropriate mix which would provide the maximum compressive strength with an acceptable permeability rate and flexural strength for the District of Columbia. The tests were conducted on the five design mixes using three different types of compaction methods (self-consolidating, half-rodding and Standard Proctor Hammer). Based on the results, a design mix with a compressive strength of 3,500 pounds per square inch (psi) with a maximum coefficient of permeability of 57.8 inches per hour (in/hr) was identified as the optimum. The maximum modulus of rupture of the selected mix was determined to be 565 psi. In-situ infiltration tests conducted of the pervious concrete installed at 3 locations in DC with the optimal pervious concrete mix yielded average infiltration rates between 86.1 and 208.7 in/hr.