SBS MODIFIED ASPHALT IN LIGHT OF SUPERPAVE, SUPERPAVE PLUS AND MULTIPLE STRESS CREEP AND RECOVERY TESTS

摘要

Polymer modified asphalt (PMA) has been found to be quite effective in improving the rutting resistance and the low-temperature cracking resistance of paving asphalt binder. In the last few years, PMAs are evaluated and tested not only by the Superpave performance grading (PG) system, but also by the Superpave Plus tests such as elastic recovery and dynamic shear rheometer (DSR) phase angle. Another multiple stress creep and recovery test (MSCR) test was recently proposed for better detection of the rutting resistance of PMA. We found in this study that by using Alberta asphalts as base, with styrene-butadiene-styrene (SBS) polymer at various levels, as the modifier; the minimum amount of polymer required to pass these tests are very similar, in the range of 2.6N to 3.0N% by weight for PG58 PMAs, where N is a constant number. For PG64 PMAs, the Superpave high-low spread is the limiting factor, I.e., PMAs passing the Superpave PG grades also met the Superpave Plus test requirements.