Book Description

This report presents findings on the effect of conditioning time on the volumetric properties of Superpave Gyratory Compactor (SGC) prepared asphalt mixtures. Field mixtures were sampled from the producing plants and then recreated in the laboratory following 3 different short-term conditioning procedures to measure the effect on the N-design value of the mixture. The projects selected represent three different N-design levels, have different nominal maximum aggregate size, aggregate sources, and asphalt binder types. Bulk Specific Gravity (Gmb) samples were aged at compaction temperature for 1-hr, 2-hr, and 4-hr. Maximum Specific Gravity (Gmm) samples were also aged at compaction temperature for 0-hr, 2-hr, and 4-hr. The short-term aging times are based off of Illinois Department of Transportation aging procedures, current National Center for Asphalt Technology recommendations, and the original Superpave conditioning specifications. It was observed in this study that increased conditioning time has a greater impact on the volumetric properties of polymer-modified binder mixes than on neat binder mixes. Also, noticed is that the presence of polymers in the binder appears to have greater effect than the higher temperatures used for conditioning polymer-modified HMA.