Ultrasonic Pulse Wave Velocity Test for Monitoring Changes in Hot-Mix Asphalt Mixture Integrity from Exposure to Moisture

Abstract

The ultrasonic pulse wave velocity test is evaluated as a possible tool for monitoring changes in the integrity of mixtures due to moisture conditioning. Two sets of mixtures were prepared. The first group involved fine-grained (above the restricted zone) and coarse-grained (below the restricted zone) limestone mixtures commonly used by the Florida Department of Transportation (FDOT) that were produced with multiple void structure and permeability configurations by varying the gradations and proportions for a common set of aggregates and asphalt cement. The second set of mixtures consisted of three granite-based mixtures commonly used by FDOT. The results presented show that the small strain modulus obtained with the ultrasonic pulse wave velocity test appears to be sensitive to changes in mixture integrity due to moisture, and therefore it may be a possible tool for the characterization of damage in both laboratory and field specimens. Additional work remains to be performed to better define the meaning of the values obtained. However, the current results indicate that the ultrasonic pulse wave velocity test may be used as an indicator of damage in specimens as well as a quick monitoring device for detecting changes in the integrity of mixtures due to exposure to moisture.