Abstract
This study evaluates the viscoelastic behavior and rheological properties of Warm Mix Asphalt (WMA) binders modified with crumb rubber (CR) and Sasobit using a Dynamic Shear Rheometer (DSR). Crumb rubber modification is an effective technique to enhance the high-temperature rutting resistance and elasticity of asphalt binders, although it substantially increases binder viscosity, creating compaction and workability challenges. To address this limitation, Sasobit, an organic wax-based WMA additive, was incorporated. A base asphalt binder (PG 64-22) was blended with crumb rubber at concentrations of 10%, 15%, and 20% by weight of the binder, alongside a constant dosage of 1.5% Sasobit. Temperature and frequency sweep tests were performed using the DSR to measure the complex shear modulus (G*), phase angle (δ), and the rutting parameter (G*/sinδ). The experimental results demonstrate a synergistic effect: crumb rubber significantly increases the binder stiffness and elastic recovery, while Sasobit reduces the rotational viscosity at compaction temperatures. The combination of 15% crumb rubber and 1.5% Sasobit was identified as the optimal formulation, successfully upgrading the high-temperature performance grade to PG 76 while maintaining acceptable workability limits.
