Effect of short-term and long-term ageing on dynamic modulus of foamed warm mix asphalt

Abstract

ABSTRACTThis study investigated the effect of short-term and long-term ageing on the dynamic modulus of foamed warm mix asphalt (WMA) produced by water injection and traditional hot mix asphalt (HMA). Four asphalt binders (PG 64-22, PG 64-28, PG 70-22 and PG 76-22) and one aggregate (limestone NMAS 12.5 mm) were used in the preparation of the laboratory-produced asphalt mixtures. The short-term and long-term ageing of the asphalt mixtures were simulated using AASHTO R 30. The experimental test results showed lower dynamic modulus values for foamed WMA than those obtained for traditional HMA for both short-term and long-term oven-aged specimens. By comparing the dynamic modulus values of the short-term and long-term oven-aged specimens, it was observed that some mixtures, such as those prepared using PG 64-22, had a smaller increase in dynamic modulus for foamed WMA mixtures than traditional HMA mixtures, while a comparable increase in dynamic modulus for both foamed WMA and HMA was observed for other mixtures, such as those prepared using PG 70-22 and PG 76-22. This suggests that the binder type plays a significant role in determining the ageing characteristics of foamed WMA and HMA mixtures.