Determination of bulk specific gravity (Gmb) of bituminous paving mixtureis an important part of the Superpave mix design system and construction quality control/ quality assurance programs. Two problems commonly associated with AASHTO T 166 are the time it takes to dry test specimens and potential damage to the sample caused by drying at elevated temperatures. A vacuum drying technique has been developed to overcome these shortcomings. Field core samples and laboratory compacted samples of dense graded HMA and SMA were obtained for testing. The objectives of the study were to determine if dry mass and resultant Gmb of laboratory compacted and pavement core samples determined using vacuum drying procedures produces statistically similar results to AASHTO T 166 procedures. A second objective was to compare the dry mass obtained from AASHTO T 166 Method A to that of Method C. Comparisons of the means were made using ANOVA techniques along with paired t-testing. The practical significance of any statistically different results was also evaluated by using the precision statement of AASHTO T 166(5). Results indicated that vacuum drying is an acceptable procedure for determining dry mass and bulk specific gravity of HMA samples.
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