Moisture susceptibility assessment of hydrated lime modified asphalt mixture and surface energy

The influence of hydrated lime on moisture susceptibility of asphalt mixture was assessed using a combination of surface energy measurements and modified saturation ageing and tensile stiffness test. Four aggregate types, which are commonly used for manufacturing asphalt mixtures in the UK have been selected. These aggregates were from various rocks across the UK which includes felsic intrusive, calcite sedimentary, mafic extrusive and argillaceous sandstone rock sources. Two out of four aggregate sources including felsic intrusive, and argillaceous sandstone showed improvement with the hydrated lime replacement, however the performance of aggregates from calcite sedimentary, mafic extrusive rocks remained unaffected. Mineralogy test results, showed significant differences among four aggregate types used in this study. The difference in the behaviour of four aggregate types to the hydrated lime replacement can be credited in part to mineralogical composition of different aggregates. The hydrated lime content of 1% was observed better than 2% in the aggregates who showed improved performance with the use of hydrated lime. The trends obtained in the surface energy measurements have been found similar to saturation ageing and tensile stiffness (SATS) test technique. The results clearly illustrate a close agreement between both techniques used in this study for the evaluation of moisture susceptibility.