Effects of hydrated lime on mechanical behaviour of asphalt concrete at nanoscale

Asphalt concrete (AC) is a mix of mineral aggregates and natural sand held together with a binder of bitumen. This paper presents the effects of adding hydrated lime (HL) to AC on the nanoscaled mechanical properties. Two hot mixes of AC were used (one control mix and one mix with HL). Nanoindentation was conducted to study the load–displacement behaviour at nanoscale and evaluate the nanomechanical (elastic modulus and hardness) properties of AC across the mastic, matrix and aggregate phases. It was observed that the HL-containing samples have greater resistance to deformation at nanoscale in the mastic and matrix phases. The resistance is more pronounced in the mastic phase. There is also strong evidence suggesting that HL has the most potent effect on the mastic phase, with significant increase in elastic modulus and hardness.