Comprehensive Evaluation of Polymer-Modified SMA Mixture Produced with New Polyethylene Wax-Based WMA Additive with Adhesion Promoter

The use of polymer-modified stone mastic asphalt (PSMA) is increased in highways and expressways because it provides high rutting resistance, a good skid resistance and noise reduction for heavily trafficked roads. However, PSMA mixture requires high mixing and compacting temperatures to create a suitable coating between polymer-modified asphalt and large size of aggregate. Warm-mix asphalt (WMA) technology is being used in polymer-modified asphalt (PMA) mixture to reduce mixing and compacting temperatures. A new polyethylene wax-based WMA additive with adhesion promoter was selected to use in PSMA mixtures at significantly lower temperature than a conventional PSMA mixture. In this study, the performance characteristics of PSMA mixture using new polyethylene wax-based WMA additive (PSMA-WMA) are evaluated against a conventional PSAM mixture without additive (PSMA-HMA) in terms of the moisture susceptibility, viscoelastic properties, rutting resistance at high temperature, fatigue resistance and crack resistance at low temperature. The mix design is carried out in the laboratory for the conventional PSMA-HMA mixture and a similar composition was adopted for the PSMA-WMA mixture (with the incorporation of 1.5% WMA additive in the bitumen) in order to evaluate the influence of polyethylene wax-based additive on the performance characteristics of the resulting mixture. Drain-Down and Cantabro test results of PSMA-WMA mixture meets the requirement of criterion. Based upon the comprehensive evaluation of PSMA-WMA mixture against PSMA-HMA mixture, it is concluded that the performance characteristics of the PSMA-WMA mixture are better than those of the PSMA-HMA mixture in the moisture susceptibility, rutting resistance at high temperature, fatigue resistance at intermediate temperature and crack resistance at low temperature. Thus, new polyethylene wax-based WMA additive is effective on reducing the production temperature without compromising the performance of PSMA-WMA mixture.