关键词: 钢渣;水侵蚀;动态模量;水化产物

Abstract: The use of steel slag instead of limestone as coarse aggregate in asphalt mixture.Two kinds of asphalt mixture with different aggregate were prepared by Superpave Gyratory Compactor(SGC).The dynamic modulus of two kinds of asphalt mixture were measured under different temperature(0℃,20℃and 55 ℃)and load frequency during the condition of water erosion and dry-wet cycles(0,1,2,3,4, 5 times).The effect of water erosion and dry-wet cycles on the dynamic modulus of two kinds of asphalt mixture was investigated,the X-ray diffraction(XRD)was used to determine the phase composition of flaky material formed in sample surface and the scanning electron microscopy(SEM)was used to examine changes in microstructure at the crack of the specimen.The experimental results show that initial dynamic modulus of the steel slag asphalt mixture without water erosion is higher than that of the limestone asphalt mixture.After 5 times of water erosion and dry-wet cycle, the dynamic modulus of all steel slag asphalt mixtures were significantly reduced,but the residual dynamic modulus at 0 ℃ and 20℃were still larger than limestone's.The results of XRD and SEM show that swell matter mainly consists of calcium hydroxide(Ca(OH)2), calcium carbonate(CaCO3), calcium silicate hydrated(C-S-H).From our results, we can conclude that the failure mechanism in steel slag asphalt mixture in moist environment is determined as the formation of Ca(OH)2, CaCO3and C-S-H, which leads to partial structural failure and facilitates water infiltration.

Key words: steel slag;water erosion;dynamic modulus;hydration product