Medhani, Rezene; Khan, Wasi; Arhin, Stephen; Howard University
District of Columbia DOT; FHWA
Compressive strength; Concrete; Flexural strength; Infiltration; Mix design; Permeability; Porosity
Pervious concrete is a mixture of cement, aggregate, and water that provides 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 results in larger air void than conventional concrete. The District Department of Transportation (DDOT) constructed pavements in selected street alleys using pervious concrete on a pilot basis. DDOT does not currently have its own specifications for pervious concrete. As a result, 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. 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 57.82 inches per hour (in/hr) was selected. The maximum modulus of rupture of the selected mix was determined to be 565 psi. The in-situ infiltration tests conducted at 3 locations in the District of Columbia (DC) with the optimal pervious concrete mix yielded average infiltration rates between 86.1 and 208.7 in/hr. This falls within the typical infiltration rate of pervious concrete (i.e., 100 to 200 in/hr, on average).