Surface treatments of waste tyres for sustainable concrete production: a performance, environmental and cost-based review

Incorporating waste tyres into concrete as a partial aggregate replacement offers a sustainable solution to reduce landfill disposal and conserve natural resources. However, the poor mechanical performance of rubberised cement-based composites (RCC), primarily due to weak interfacial bonding, low rubber stiffness, and hydrophobicity, limits their practical applications. This review presents a comprehensive and systematic evaluation of studies published between 2000 and 2025 on physical, chemical, and combined surface treatment strategies aimed at enhancing the rubber–cement interface, increasing rubber stiffness, and improving the mechanical performance of RCC. Using the strength recovery factor (SRF) as a comparative metric, the most effective single and combined treatment strategies are identified, and the environmental impacts and associated costs of these treatments are systematically evaluated and compared. The results indicate that among single treatments, partial oxidation, heat treatment, NaOH treatment, and fly ash coating achieved the greatest improvements across the reviewed studies, providing 84–94% strength recovery at rubber replacement levels up to 10%. Combined treatments, including NaOH-treated rubber coated with high-performance cementitious materials or blended cement with silica fume and Na₂SiO₃, showed the highest effectiveness, attaining 93–102% strength recovery at a 15% rubber replacement level. Environmental and cost analyses reveal that heat treatment and NaOH-treated rubber coated with blended cement containing silica fume and Na₂SiO₃ are the most sustainable single and combined approaches, respectively. Finally, future perspectives are outlined for the development of eco-friendly, cost-effective, and efficient treatment methods to advance the sustainable application of RCC.