Potential for Clay Clogging of Pervious Concrete under Extreme Conditions

Pervious concrete is a novel paving material with macropores that aid in maintaining natural hydrologic infiltration rates on developed properties. There is a concern that the pores in the pervious concrete might clog due to long-term deposition of fine materials in runoff, or due to a catastrophic event(s) such as the failure of upstream erosion control measures or flooding. This research focuses on these extreme events and presents a laboratory procedure mimicking a series of catastrophic clogging cycles with clay laden runoff. It is predicted that the clay materials would tend to remain near the surface of pervious concrete systems since most placements have a vertical porosity distribution with the smaller pores near the top. The cores used were from actual field placements and the results indicate that extreme events with substantial deposition of clay on a pervious concrete pavement will substantially reduce its service capability, even temporarily fully “clogging” the pavement. However, most of the clay remains on or near the surface and the infiltration capacity of the pervious concrete was restored to acceptable, although lower, levels with simple maintenance such as surface sweeping, and subsequent rinsing similar to subsequent rainfall events.