The theoretical maximum specific gravity of loose asphalt mix, the ratio of its density with zero air voids to the density of water. It is measured on uncompacted mix by the vacuum flask method that crews call the Rice, and values land around 2.4 to 2.6 depending on the aggregate. Every in-place density and air void percentage is reported against Gmm, so an out-of-date Gmm can turn a passing mat into a failing one on paper.
Gauge says 93.5 percent of Gmm, but that's on last week's value, get the new one from the lab before anybody signs the sublot.
Also heard as
- maximum theoretical specific gravity
- max gravity
- Rice gravity
Related terms
Rice
Lab slang for the maximum specific gravity test on loose mix, and for the Gmm value it produces.
Air voids
The small pockets of air between binder-coated aggregate in compacted mix, given as a percent of total volume.
Density
How tightly a compacted asphalt layer is packed, reported as a percentage of its maximum theoretical density.
Nuclear gauge
A portable instrument with a radioactive source that estimates asphalt density in about a minute without cutting a core.