ABSTRACT

This research focused the impact of various aggregate gradations on permanent deformation and moisture susceptibility of asphalt concrete mixtures. Five wearing course of different gradation, namely NHA-A, NHA-B, SP-1, SP-2 and MS-2, were adopted. Two paving grade bitumen i.e. 40/50 and 60/70 were used. Hamburg Wheel Tracking Test (HWTT) and Modified Lottman test were performed to assess rutting propensity and moisture damage of asphalt mixtures. The results indicated the superior performance of NRL 40/50 binder in HWTT while mixes prepared with Parco 60/70 showed better resistance against moisture. In HWTT, NHA-A performed well followed by NHA-B and SP-2 while MS-2 and SP-1 failed the minimum rut depth criteria. All the mixtures passed the minimum benchmark for Tensile Strength Ratio (TSR). Aggregate gradation SP-1 given in Superpave guidelines provided greater resistance to moisture damage due to compact nature of the blend. Rutting tendency of the mixtures increased with increasing TSR and decreasing Indirect Tensile Strength (ITS).