Linear Viscoelastic Properties and Rutting Resistance of Asphalt Mixtures Modified with Crumb Rubber and Polymer-Covered Sulfur

Modification of bitumen with different modifiers already has been done in order to modify rheological properties of neat bitumen to ideal bitumen. The point which has to be considered is that asphalt mixture fabricated with this modified bitumen has to show appropriate performance which is expected. Also, environmental consistent with appropriate price materials should be used to modify bitumen. In this research, bitumen modified with crumb rubber and polymer-covered sulfur were prepared using high shear rate mixer. After fabrication of modified and unmodified asphalt mixtures according to Superpave method, dynamic modulus and dynamic creep tests were conducted on them to investigate their performance and mechanical properties. From the results of dynamic modulus test, linear viscoelastic characterization accomplished and dynamic modulus master curves were developed. Comparison of those master curves showed that asphalt mixture with 40 percent polymer-covered sulfur has the highest dynamic modulus in high temperatures (low frequencies). Then, asphalt mixture with 20 percent crumb rubber has higher dynamic modulus compared to control asphalt mixture. Also, dynamic creep test results at 50 ᵒC showed that asphalt mixture modified with polymer-covered sulfur has the most resistance to rutting, and then, asphalt mixture modified with crumb rubber is more resistant to permanent deformation compared to control asphalt mixture.