Rubber Aggregate Concrete with Enhanced Damping Performance for Mass Concrete Applications

Mass concrete structures are subjected to long-term dynamic excitations, yet traditional concrete lacks the damping needed for effective vibration control. Rubber aggregate concrete has shown promise for vibration mitigation, but how rubber particle size and replacement ratio govern damping mechanisms and thermal performance in mass concrete remains unclear. Here we study rubber aggregate concrete with two particle sizes (40-mesh and 100-mesh) at 5%, 10%, and 20% sand replacement, combining mechanical, thermal, and dynamic testing with multi-scale microstructural characterization including FTIR, MIP, and nanoindentation. The damping ratio increased by up to 110% (from 1.43% to 3.01%), the adiabatic temperature rise decreased by 32%, and the linear expansion coefficient by 88%. Three damping mechanisms were identified: rubber viscoelasticity, interfacial friction at the weak rubber–mortar interface, and pore and micro-crack energy dissipation. Finer 100-mesh rubber outperformed coarser 40-mesh at higher replacement ratios due to a micro-filler effect that refined pore structure. RC-20-100 achieved 26.6 MPa at 90 days, adequate for non-primary structural elements. We recommend 20% fine rubber as the optimal balance of high damping, thermal crack mitigation, and adequate strength for vibration-controlled mass concrete applications.