Rheological and Mechanical Evaluation of Polyurethane Prepolymer-Modified Asphalt Mixture with Self-Healing Abilities

Abstract

The objective of this study was to evaluate the effect of an innovative UV light-activated self-healing polyurethane prepolymer (SPP) on the rheological, mechanical, and self-healing properties of asphalt mixture. This new additive combines polymer modification and self-healing capability into one modifier in order to enhance the mechanical properties of asphalt mixture, while increasing its crack healing rate. For this purpose, asphalt mixtures were prepared with asphalt binder modified with three percentages (5%, 10%, and 15%) of self-healing polyurethane prepolymer. A self-healing test was performed to evaluate the rate of crack healing in asphalt mixtures prepared with or without self-healing polyurethane. Furthermore, a Semi-Circular Bending test and a Loaded Wheel Tracking test were conducted to study the fatigue and rutting resistances of the prepared samples. Asphalt binder was also extracted from the samples and was tested using the dynamic shear rheometer and bending beam rheometer. An increase in the crack healing rate was observed with 5% and 10% self-healing polymer; however, when the SPP percentage was increased to 15%, the healing efficiency was affected adversely. The addition of SPP also led to an improvement in the cracking and rutting resistances. Results from the rheological test showed that SPP resulted in an increase in the high-temperature grading while the low-temperature grading was not affected. Furthermore, multiple stress creep recovery test results showed an improvement in the elastic recovery and rutting resistance of the binder extracted from aged and unaged asphalt mixtures.