Infiltration and Clogging by Sand and Clay in a Pervious Concrete Pavement System

From a hydrologic perspective, one limitation of pervious concrete pavement is the risk of clogging, defined as a reduction in hydraulic conductivity that reduces infiltration into the pavement or exfiltration into the subgrade. Accordingly, a laboratory study was performed to measure clogging by sand and clay (sodium montmorillonite) in a saturated pervious concrete pavement system, and the subsequent effect of surface cleaning by pressure washing. Both sand and clay caused measurable clogging that was not reversible by pressure washing. However, even after clogging, the infiltration and exfiltration rates were well above the average intensity of 66 mm/h for the 100-year 1-h design storm for Denver. This result is encouraging, but should be interpreted with caution, because in these experiments the flow-limiting layer was never the pervious concrete, but rather the subgrade, which in this case was a thin layer of sand with a large hydraulic conductivity. Accordingly, this study suggests that pervious concrete would be effective for storm-water detention when provided with an engineered drainage system, but that its performance for storm-water infiltration will be limited by the rate of exfiltration to the subgrade. DOI: 10.1061/(ASCE)HE.1943-5584.0000424. (C) 2012 American Society of Civil Engineers.