Accelerated Pavement Testing of Drained and Undrained Pavements Under Wet Base Conditions

The California Department of Transportation requires that all new flexible pavements include a 75-mm layer of asphalt-treated permeable base (ATPB) between the asphalt concrete and aggregate base layers. The purpose of the ATPB layer is to intercept water entering the pavement, either through cracks in the asphalt concrete or through high-permeability asphalt concrete, and to transport it out of the pavement before it reaches the unbound materials. Results are presented of a study using heavy vehicle simulator (HVS) trafficking to evaluate the performance of drained and undrained flexible pavements under wet conditions. A drained structure is a pavement section that contains an ATPB layer between the asphalt concrete and aggregate base. An undrained structure is a pavement section that does not contain an ATPB layer. Wet conditions intend to simulate approximate surface infiltration rates that would occur along the northwest coast of California during a wet month for a badly cracked asphalt concrete layer. Results of the accelerated pavement testing indicate that ATPB strips under combined conditions of wet base and heavy loading. Drained and undrained sections have similar pavement lives; however, the primary mode of failure for the drained section was surface rutting and for the undrained sections it was fatigue cracking.