Factors That Affect the Voids in the Mineral Aggregate in Hot Mix Asphalt

摘要

The Colorado Department of Transportation (CDOT) will be specifying a minimumVoids in the Mineral Aggregate (VMA) for the 1993 construction season. The purpose of the report was to provide guidance and information for obtaining VMA. 101 of the mix designs performed by the CDOT during 1992 were analyzed to determine the most appropriate method for drawing the maximum density line. The Texas reference gradation line and the line drawn from the origin to the actual percent passing on the nominal maximum aggregate size provided the best correlation with measured VMA. Staying away from the maximum density line at the No. 30 sieve and the fourth largest sieve to retain material is advised. In addition, 24 laboratory mix designs were prepared to examine the effect of varying four variables considered important in obtaining VMA: gradation, quantity of P200, size of P200, and fine aggregate angularity. The gradation provided the largest changes in VMA. The quantity of P200 and angularity also caused significant changes to VMA. The quantity of P200 made more substantial changes to the VMA of fine gradations than coarse gradations.