If the mixture has sufficient binder, the air voids are controlled by the aggregate gradation. Back To Top Back To Contents Part 3. Definitions Specific Gravity is the ratio of the weight in air of a unit volume of a material to the weight of an equal volume of water at the same temperature. There are two specific gravity measurements used when discussing asphalt mixtures. The theoretical maximum specific gravity is measured on the uncompacted asphalt cement and aggregate mixture.
Specific gravity has no units.
HMA density may be determined either on a laboratory compacted specimen of asphalt mixture, or on a core or sawed section of the in-place pavement. Nuclear density gauges have two advantages in that they determine results rapidly and they are nondestructive. Nuclear gauge densities should be correlated with core densities taken from the same location to determine the true in-place density of each lift of construction. Back To Top Back To Contents Part 4. A density specification represents a comparison between the in-place density of the pavement that is achieved after final compaction, and a reference density.