7.5.1 Dilation Point Method
The dilation point method, which was devised by the American National Center for Asphalt Technology (NCAT) and then adopted in Australia (Stephenson and Bullen, 2002), serves to determine the maximum content of aggregate less than 4.75 mm (i. e., the passive fraction), which still does not cause the dilation of the coarse aggregate (i. e., the active fraction). The method consists of preparing a series of samples with various contents of fine aggregate. The samples are compacted in a gyratory compactor with a constant content of binder and stabilizer. According to the rule, voids among the coarse aggregate are gradually filled with passive particles. This has an impact on the SMA’s particular properties; in the Australian method the resilient modulus is examined. The point at which a skeleton is filled with passive particles is determined through an analysis of the height of samples during compaction in the gyratory compactor. Tests of different contents of fine aggregate at various screenings through 4.75, 2.36, 1.18, and 0.6 mm sieves have been conducted.
