About the research
The final report for this project provides an integrated selection procedure for evaluating whether an existing hot-mix asphalt (HMA) pavement is an appropriate candidate for a bonded concrete overlay of asphalt (BCOA). The selection procedure includes (1) a desk review, (2) coring, (3) visual examination (site visit), (4) additional coring and/or laboratory testing (optional), (5) preparation of preliminary estimates (optional), and (6) a final report with design recommendations.
This project also included an analysis of material testing performed by the Minnesota Department of Transportation (MnDOT) on numerous HMA cores to determine if the performance of existing BCOAs could be correlated to HMA material properties. The results of the laboratory testing were inconclusive. None of the existing HMA material properties tested could be correlated to long-term BCOA performance due to the high variability among the measured parameters within a section, the small number of cores per section, and the fact that the sections investigated exhibited little or no distress that could be attributed to the asphalt layer’s properties. Although no conclusions could be made from the limited laboratory testing, it is fair to say that the BCOAs from these projects were performing as designed.