Case Study on Premature Pavement Failure and Successful Reconstruction of a High RAP Section at the NCAT Test Track

摘要

The objective of this case study was to document an unanticipated pavement failure, the subsequent identification of the failure mechanism, the rapid redesign, and successful reconstruction of an experimental section containing higher-than-normal amounts of reclaimed asphalt pavement at the National Center for Asphalt Technology Test Track. The failure mechanism was identified as debonding between the base and intermediate asphalt concrete lifts, which led to middle-up cracking. Although the section was designed to develop distresses within the two years of trafficking, with the intent to evaluate the entire pavement structure, layer interface debonding inhibited that goal. A laboratory tack coat study was promptly conducted to determine the optimal amount of tack necessary to provide a bond between layers that would withstand the accelerated loading applied at the Test Track. Multiple corrective actions were taken during reconstruction to ensure that this premature failure would not recur. The tack coat application rate was doubled and the mix temperature of the intermediate lift was increased. Since reconstruction, performance evaluations that included falling weight deflectometer testing, instrumented pavement responses and surface distress monitoring have indicated that the section is performing well. This paper compiles the performance evaluations (original and reconstructed), with laboratory testing, and construction quality control results to disseminate the lessons learned.