Investigating the Rheological and Physical Properties for Unaged of Crumb Rubber-Modified Binders Containing Warm Mix Asphalt Additive

The growing usage of crumb rubber modified in flexible pavements justification and the requirement for a good comprehension of its physical and rheological properties as well as its elastic behaviors. However, crumb rubber asphalt mixtures demand rising product temperatures than traditional asphalt binder due to the high viscosity of asphalt rubber binder. The main points of this research are to investigate the unaged rheological and physical properties of crumb rubber modifier (CRM) asphalt. In this study, crumb rubber-modified percentages was 0, 5, 10, and 15% from the binder weight, with adding 1.5% warm mix asphalt additive (Sasobit). The wet method was used to mix the CRM with bitumen, the CRM conducted at 177 °C for 30 min whit 700 rpm, and Sasobit conducted at 120 °C for 10 min with 1000 rpm. The results display that various crumb rubber contents have important impacts on modified binder properties. The result shown that increase the complex shear G* and decreased the phase angle δ at high temperature with increased the CRM contents. The rutting resistance parameter was rising with increased CRM percentages at 70 °C. The softening results in rise in the temperature with adding the CRM and the penetration results in reduction with the growing CRM contents. The elastic recovery increased with higher CRM content. The storage stability was within the range for unmodified and 5% of CRM but for 10 and 15% the result was over the range. From the results we conclude that the CRM improves the elasticity and improves the stiffness of the modified binder.