Effect of cross-linkers on the performance of polyethylene-modified asphalt binders

Phase separation or lack of storage stability is one of the challenges of using polymer-modified binders in flexible asphalt road pavements. Meeting this challenge while maintaining the performance of these binders is of great interest to pavement engineers. The research reported in this paper aimed to solve the problem of the susceptibility of binders modified with high-density polyethylene to phase separation by using cross-linking agents. Sulfur and polyphosphoric acid were selected to improve the storage stability of the polyethylene. These materials were added to a 60/70 penetration graded asphalt binder in different amounts, and a cigar-tube test was performed to determine the separation tendency of the polyethylene. In addition, a linear-amplitude sweep test was used to evaluate the fatigue performance of the resulting binders. The results showed that, unlike sulfur, polyphosphoric acid improved the storage stability and performance against fatigue of the polyethylene-modified binders.