Performance evaluation of concrete pavement incorporating recycled rubber tire mulch for urban heat island mitigation

The global generation of approximately 1.5 billion end-of-life tires (ELTs) annually presents a significant environmental challenge, with traditional disposal methods like landfilling and incineration contributing to greenhouse gas emissions and health risks. This study explores the use of recycled rubber tyre mulch as a volumetric fiber additive in cement mortar, aiming to enhance thermal insulation and mechanical durability while offering a sustainable solution for ELT waste management. Unlike conventional approaches that replace sand or aggregate with rubber, often at the expense of compressive strength, this research evaluates rubber in addition to fiber form to retain structural integrity. Experimental results reveal that mortar specimens containing 10% and 20% rubber fibers exhibit surface temperature reductions of approximately 2.8 °F after 1 h and 4 °F after 2 h of heating, attributed to rubber’s low thermal conductivity and porous microstructure. Although a 71.5% reduction in compressive strength was observed at 20% rubber tire incorporation, the values remained within the permissible range for non-structural applications, mechanical characterization indicates improved fracture toughness and ductility, supported by mechanisms such as crack bridging and deflection. The findings demonstrate that incorporating rubber fibers can reduce pavement heat retention and enhance durability, contributing to urban heat island mitigation and promoting circular economy principles in construction materials.