Saskatchewan Ministry of Highways and Infrastructure commissioned a ground penetrating radar (GPR) survey to develop a non-destructive methodology for performing post construction quality assurance characterization of a newly upgraded flexible pavement structure. The survey employed multiple passes of GPR to determine conventional hot mix asphalt concrete (HMAC) surfacing quality assurance measures including layer variability thickness and density. The GPR survey found that 21 percent of the southbound lane and 14 percent of the northbound lane showed low, moderate, or high severity surfacing variability. It was also determined that more asphalt mat variability was present towards the outside of both lanes. Based on the results of this study, GPR was found to provide a measure of HMAC surface irregularity, as well as the severity of the surface variability. The pilot GPR analysis correlated well with the visual condition survey of the surface. As well, the GPR measured HMAC layer thicknesses were validated as they correlated well with retrieved HMAC core thicknesses. However, the GPR did not provide an adequate correlation to surface density. In summary, this research demonstrates that GPR may be a valuable non-destructive measurement tool to provide quality assurance measures of mat thickness and variability of HMAC surfaces in Saskatchewan.
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