| Non-uniformity is a serious problem in hot-mix asphalt pavements. Minimizing non-uniformity is essential to improve pavement performance and reduce maintenance and rehabilitation cost. However, standard quality control/quality assurance procedures which randomly define sampling locations have a low probability of capturing non-uniformity of the in-placed asphalt mixture.; This research seeks to develop a technique to quantify non-uniformity in HMA pavements. Multivariate statistical technologies were adopted to develop models for aggregate segregation, the main type of non-uniformity. Segregation was simulated in the laboratory; performance of the simulated specimens was evaluated with the Asphalt Pavement Analyzer test, the Repeated Shear at Constant Height test, and the Frequency Sweep at Constant Height test. Analysis of the test results indicated that segregation could be classified into three levels. New models with segregation levels, good, fair, and unacceptable, were established for aggregate segregation.; Based on laboratory and field investigation, a methodology to assess non-uniformity is proposed. In this method, density variations are measured across a pavement in real time. Non-uniformity was evaluated by combining non-destructive density measurements and destructive core analysis. It is recommended that agencies and contractors consider implementing the initial methodology in their construction practices to promote uniformly placed, non-segregated pavements. |
