EFFECTS OF AGGREGATE, SASOBIT, AND HYDRATED LIME ON MOISTURE SUSCEPTIBILITY OF ASPHALT MIXTURES

摘要

Moisture susceptibility of asphalt layer is one of the major causes of premature pavement failures, decreasing the performance and service life of pavement. Many variables affect the amount of moisture damage in the asphalt mixtures; such as the type of aggregate, bitumen, additive properties that are introduced to the bitumen, mixture design and construction, environmental conditions, and level of traffic. This study focused on investigating the effects of aggregate characteristics, additives such as Sasobit (an organic WMA additive), and hydrated lime as mineral filler on moisture resistance of asphalt mixtures. Sasobit concentrations tested were 1.5, 2.5, 3.5 percent of base bitumen (PG64-22), and lime marinated mixtures contained 1, 1.5, 2 percent of hydrated lime by the weight of aggregate. The modified Lottman test (AASHTO T283) was used to calculate Tensile Strength Ratio (TSR %) for asphalt specimens. Indirect Tensile Test (IDT) showed that each of techniques, hydrated lime addition and Sasobit modification, increased the resistance of asphalt mixtures to the detrimental effects of freeze and thaw cycles. Moreover, two different sources of aggregates were used and the results are corresponded with aggregates specifications.