IN-PLACE VOIDS MONITORING OF HOT MIX ASPHALT PAVEMENTS

In 1995, the Colorado Department of Transportation implemented the Superpave gyratory mix design to select the optimum asphalt content of a mixture. The optimum asphalt content was not the same as what the department had historically used. The purpose of this study was to gather data to validate the number of gyrations that should be used with the Superpave mix design. Based on the data gathered from the 25 evaluation sections, the optimal number of design gyrations for the Field Mixed/Lab Compacted material is too high. Mixes appear to be too stiff for the traffic and environmental conditions. Based on the results from this study, two options are recommended to improve design mixes for Colorado's traffic and environmental conditions: (1) Lower the number of gyrations; and (2) Adjust the target mix design air void content. Additional research is recommended to track the adjustments that are made to ensure the desired outcome is achieved.