Chemical inhibition of wax precipitation to improve cracking resistance of warm mix asphalts

Abstract

In recent years, the wax-based warm mix additives are always doped into the asphalt to lower the construction temperatures, which can lead to the substantial energy savings and promote energy sustainability. However, few studies have considered the methods to inhibit the premature precipitation of wax-based warm mix additives in warm mix asphalt, which will deteriorate the cracking resistances of asphalt pavement. This paper introduced a new method from the essence of the phase separation between the wax-based warm mix additives and asphalt leading to the reduction of cracking resistance, which chemically inhibited the premature precipitation of common additives (linear aliphatic hydrocarbon (LAH), polyethylene (PE), fatty acid amides (FAA), and Fischer-Tropsch (F-T) waxes) by wax inhibitors (WIs) to improve the compatibility of additives, and the cracking resistances of warm mix asphalts with addition of WIs were also investigated through the multi-stress creep recovery (MSCR), linear amplitude sweep (LAS), dynamic mechanical analysis (DMA), and thermal fatigue tests. The results show that the wax precipitation temperature (WPT) of warm mix asphalt reduces with the addition of WIs to inhibit the precipitation of additives to improve the compatibility, and the wax inhibition efficiencies of WIs are better with the asphalt doped with short-chain additives at higher content. The WIs can provide the warm mix asphalt with the additional elasticity and decrease the dependency on the applied strain, which increases the high-temperature rutting and intermediate-temperature fatigue resistances. The cracking and thermal fatigue resistances of warm mix asphalt at the low temperature can also be improved after doping with WIs, which is leaded by the precipitation inhibition of additives. Therefore, it is promising to improve the cracking resistances of warm mix asphalts and develop a new energy-saving pavement by chemically inhibiting the precipitation of additives.