Study on the Criterion of SMA Framework

From the traditional point of view, the criterion of framework for SMA (stone matrix asphalt) mix is that V DRC (the voids in coarse aggregate on the dry rodded condition) must be larger than V Mix (the voids in coarse aggregate of mix). However, there are several facets, such as the compaction method, the measuring precision, and the density conversion for calculating the voids in coarse aggregate, which could cause system errors. Consequently in many cases V DRC is always larger than V Mix , and the optimal gradation can not be realized. The test results show that the V Mix which is calculated with the bulk density measured by calipers is fairly reasonable. There is a turning point in the curve for the V Mix versus the percentage of the fine aggregate passing the 4.75 mm sieve. It is feasible to use this turning point to evaluate the formation of coarse aggregate skeleton in a SMA mix.