Evaluating the suitability of CRMB for high performance asphalt applications

High modulus asphalt concrete is widely used in regions with hot/mild weathers and ultra-heavy traffic due to its superior stiffness and durability. However, its use in cold climates is limited, as the stiff binders typically employed become brittle at low temperatures. To address this, high performance asphalt concrete (HPAC) tailored for cold regions is needed. This study explores the optimization of crumb rubber modifier (CRM) content for HPAC applications, targeting a high-temperature performance grade (PG) of 82 as a performance benchmark. A PG 64-22 binder was modified with 30 mesh (600 µm) CRM at 3%–15% concentrations and blended for 30–90 min at 180 °C. The dynamic modulus curve confirmed that 12% CRM achieves the PG 82 target, striking a balance between stiffness and flexibility. Blending time optimization showed no significant difference in PG across durations, allowing for shorter blending times, supporting the feasibility of in-field blending. Although storage stability due to phase separation remains a concern, in-field blending effectively addresses this issue and enhances practical applicability.