Study of the amine-based liquid anti-stripping agents by simulating hot mix asphalt plant production process

Stripping is one of the major distresses threatening the longevity of hot mix asphalt (HMA) pavements. Numerous types of liquid anti-stripping agents have been introduced to reduce moisture susceptibility of the Asphalt in HMA pavements. However, laboratory findings on the asphalt binder samples might be quite different with the actual conditions of mixing processes in asphalt plants. In HMA production plants, HMA mixtures and/or asphalt stored in asphalt storage tanks, are kept at high temperatures for hours, which drastically reduces the effectiveness of liquid anti-stripping agents. In this study, it is intended to simulate the HMA production conditions and then investigate the impacts of two types of liquid amine-based anti-stripping agents on the performance of HMA using the tensile strength ratio (TSR) and semi-circular Bending (SCB) tests. Results of this study indicated that effectiveness of these additives was significantly decreased after long-term being heated for HMA production. It is recommended that use of the manufacturer's suggested percentages of liquid anti-stripping additives, should be carefully reexamined with regard to production conditions.