Chemical Modification of Waxes to Improve the Compatibility with Asphalt Binders

Existing wax-based warm mix additives have poor compatibility with asphalt binders, which results in premature wax precipitation and cracking of the asphalt pavement. However, there are few studies on improving the compatibility between the waxes and asphalt. In this study, the wax precipitation temperature (WPT) was recommended as a new suitable evaluation index of the compatibility according to the consistency of changing laws between the solubility parameter distance deduced from Hansen solubility parameter (HSP) experiments and WPT, and a new component of wax-based warm mix additives with better compatibility was also introduced by maleation of the natural waxes. On this basis, the low-temperature cracking resistance of maleated natural waxes was systematically compared with that of unmodified natural waxes and commercial wax-based warm mix additives through dynamic mechanical analysis (DMA), extended bending beam rheometer (Ex-BBR), and double edge notched tension (DENT) tests. The results show that the reactant temperature has the greatest influence on the grafting effect, and the maleated natural waxes with better compatibility can reduce the viscosity, WPT, physical hardening rate, and grade loss and also improve the ductile resistance compared with the unmodified natural waxes and commercial wax-based warm mix additives. The maleation of waxes is a promising method for improving the compatibility of the waxes and asphalt.