Impact of salt and freeze-thaw cycles on performance of asphalt mixtures in coastal frozen region of China

The impact of salt on asphalt binders was first studied through basal experiments of binders. The complex influence of freeze-thaw cycles and salt on strength, volume and weight of three types of asphalt mixtures was then investigated through freeze-thaw tests. Test results indicate that salt has a significant effect on the low temperature performance of asphalt binders; Freeze-thaw is a main influencing factor when the percentage of salt is less than 3%, and the erosion effect of salt accelerates the failure of asphalt mixtures when the percentage of salt is more than 3%. The damage of asphalt mixtures is initiated by ice expansion load and accelerated by the interfacial damage between asphalt and aggregate or fracture of asphalt mortar. It can therefore be concluded that different types of asphalt mixtures have fixed residual lives after a number of freeze-thaw cycles. Freeze-thaw cycles, salinity, percent air void, asphalt property and 4.75. mm percent passing are main factors having an influence on freeze-thaw strength.