Evaluation of Various Test Devices for the Measurements of Aggregates and Asphalt Mixtures' Specific Gravity

Current test procedures for determining the density properties of aggregate and hot mix asphalt mixtures (HMA) are time consuming and subjective. The density can have significant impact on the performance of asphalt pavements. Three devices (SSDetect, CoreLok, and CoreDry) which can significantly reduce testing time were independently evaluated. Three experiments were performed to evaluate these devices. In the first experiment, specific gravity and absorption of two aggregate types (coarse sand and number II limestone) were conducted. The second experiment evaluated the HMA mixture bulk specific gravity (G(mb)) of two mixture types (open graded friction coarse and dense graded). The last experiment examined the HMA G(mb) of roadway cores. It is noted that the results from these test devices were compared to their counterpart conventional ones. Ten laboratories in Louisiana participated in this experimental program. In general, the SSDetect single operator and multilaboratories precision of both aggregate specific gravity measurements were better than that determined from American Association of State Highway Transportation Officials (AASHTO) T84. Furthermore, the results from the SSDetect device did meet the AASHTO precision criterion. Also, HMA G(mb) precision values for the CoreLok were similar to that of AASHTO T166 for both mixtures. HMA G(mb) values computed from results of the CoreDry device were similar to the ones determined from conventional method for the roadway cores.