University of California Pavement Research Center

This report presents the data for the accelerated pavement testing (APT) program conducted using the Heavy Vehicle Simulator (HVS) on Section 544. This section is part of the accelerated test program described in the test plan for CAL/APT Goal 5, “Performance of Drained and Undrained Flexible Pavement Structures under Wet Conditions.”(1) Section 544 was tested to evaluate the performance of a typical California “undrained” pavement section under wet conditions and to compare its performance with that of Section 543 (a drained pavement section) in the same condition. From the Caltrans standpoint, an “undrained” pavement section is a conventional flexible pavement that does not have a permeable layer between the asphalt concrete and the aggregate base. A “drained” pavement section is a conventional flexible pavement that includes a 75-mm layer of asphalt treated permeable base (ATPB) between the asphalt concrete and aggregate base connected to a drainage system at the shoulder. 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 carry it out of the pavement before it reaches the unbound materials layers where it may lead to a reduction in stiffness and resistance to rutting. Wet conditions for Section 544 were intended to simulate surface infiltration rates that would occur along the north coast climate region of California during a wet month for a badly cracked asphalt concrete layer.(2) Because the pavement surface course of Section 544 was initially uncracked, water was introduced through small holes drilled through the asphalt concrete into the aggregate base.