Example R02: Old Composite Pavement

This example illustrates how to design for the rehabilitation of an existing composite pavement resulted from a rigid pavement being overlaid with asphalt concrete.

The project is located at the same location as the one in Example R01. As mentioned there, the outside lanes of the mainlines are composite pavements. The FWD backcalculation results for the outside lanes can be found in the same CalBack export file so it has been imported as well as part of Example R01.

After reviewing the backcalculated stiffness of each individual segment in CalBack, the Southbound Lane 3 was found to be the weakest segment and is used in this example.

The following are the design requirements:

Must maintain grade

20 year design TI of 15.0 with a growth rate of 2%, specified by the office of traffic operations (note that this is much higher than the inside lanes)

According to site investigation (core logs and DCP data) and as-built plans, the existing structure for the inside lanes can be simplified as:

•0.1 ft of RHMA-O

•0.65 ft of HMA

•0.75 ft of PCC

•0.42 ft of cement treated base

•1.0 ft of lime stabilized subgrade

•CL subgrade

After updating project location and design traffic and removing the 0.1 ft of RHMA-O, save a copy of this trial under a new name: "SBL3_540-495: Baseline". The input page of the segment is shown below: