Moisture-induced damage resistance of asphalt mixture entirely composed of gneiss and steel slag

Gneiss and fine steel slag are seldom used in the construction of asphalt pavement due to their poor performances. Asphalt mixture entirely composed of gneiss (coarse aggregate) and steel slag (fine aggregate and asphalt filler) was proposed in this research in order to promote their wide use. Limestone fine aggregate and filler were functioned as control groups. The inadequacy of using 100% of gneiss to prepare asphalt mixture and the performance deterioration mechanism of fine steel slag were discussed based on some newly revealed material characteristics and previous research results, and corresponding improvement measures were established first. Then four asphalt mixtures (two fine aggregate and two filler) were designed by Superpave procedure. Finally, the moisture stabilities of uncompacted aggregate-mastic system and compacted asphalt mixture were fully investigated, and hot water damage mode and freeze-thaw damage mode were adopted. Results suggested that asphalt mixture entirely composed of coarse gneiss and re-processed fine steel slag possessed satisfactory moisture resistance performance.