Evaluation of the Crack Resistance of Hot Mix Asphalt Mixtures Modified with Enprene 611 Elastomer

Abstract

In this study, the crack resistance of Hot Mix Asphalt (HMA) mixtures prepared using neat bitumen and bitumen modified with Enprene 611 elastomer was experimentally investigated through the Semi-Circular Bending (SCB) test. Asphalt mixtures were produced by incorporating 2%, 3%, and 4% Enprene 611 elastomer, by weight of the binder, into B70/100 penetration-grade bitumen. The compacted cylindrical specimens were cut into two equal halves, and artificial notches with depths of 10, 20, and 30 mm were introduced at the center of each semi-circular specimen to obtain SCB test samples. The SCB tests were conducted at 20°C and 40°C to evaluate the combined effects of temperature and notch depth on the fracture behavior of the asphalt mixtures. The experimental results demonstrated that the mixtures containing 4% Enprene 611 consistently exhibited the highest maximum fracture load (Pmax) at all notch depths and test temperatures, significantly outperforming both the neat and the other modified mixtures. Furthermore, increasing the Enprene 611 content considerably enhanced the deformation resistance, cohesive bonding strength, and crack propagation resistance of the asphalt mixtures. Overall, the findings indicate that Enprene 611 is an effective polymer modifier for improving the fracture performance and mechanical durability of hot mix asphalt mixtures.