Laboratory evaluation of the effect of nano-organosilane anti-stripping additive on the moisture susceptibility of HMA mixtures under freeze–thaw cycles

The objective of this research study was to evaluate moisture susceptibility of hot mix asphalt (HMA) with and without Zycosoil as a nano-organosilane anti-stripping additive and hydrated lime in the form of slurry. Moisture resistance was evaluated on mixtures prepared with two sources of aggregate: limestone and siliceous. The base bitumen used was AC 60–70 grade, and two anti-stripping additives. The functional characterization of the base bitumen with and without Zycosoil was analyzed by means of Fourier Transform Infrared Spectroscopy (FTIR). The performance of HMA mixtures under multiple freeze–thaw cycles was evaluated through the following tests: resilient modulus; indirect tensile strength; tensile strength ratio and fracture energy. The findings of this research indicate that use of both additives enhanced the resilient modulus ratio of the mixtures. It was also observed that the effects of anti-stripping additives on specimens made by siliceous aggregate are more pronounced than those prepared with limestone aggregates. Fracture energy results also proved that use of Zycosoil additive will increase adhesion bond between the aggregates and asphalt binders, and in turn influences the moisture resistance of the mixture to moisture damage.