De-Bonding of HMA Pavements/Core Logs

Core Logs

A set of core logs was obtained from the WSDOT Materials Laboratory and analyzed for evidence of de-bonding. These logs were opportunistically gathered by the Materials Office and do not represent complete information or a statistical sample. In all, 3,042 core records were analyzed. These cores were grouped by identifying number or general location such that 194 substantially different locations on the WSDOT network were identified. Table 1 summarizes information in the core logs.

These core locations are mapped at:


Table 1: Information Available in the WSDOT Materials Office Core Data


Final numbers on the core logs are as follows:

  • Cores taken: 3,042
  • Cores with documented de-bonding: 328 (10.8%)
  • Projects represented: 194
  • Projects with documented de-bonding: 54 (27.6%)
  • Projects with evidence of de-bonding at overlay interface: 18 (9.3%)

For the 18 projects that showed de-bonding at the overlay interface the Washington State Pavement Management System (WSPMS) was consulted to determine the life of the de-bonded overlay (Figure 1).


Figure 1: Age between the overlay that was de-bonded and the subsequent overlay in preparation for which the coring was done. This gives an idea of how long the de-bonded surface lasted. Red (light) shaded bars represent projects that were not yet overlayed as of 2006.