Unveiling the Effects of Waste Tire Rubber on Concrete: A Multi-Scale Review from Macro Performance to Microstructure

Rubberized concrete (RC) has emerged as a critical solution for valorizing waste tires, offering a dual benefit of environmental sustainability and functional enhancement. This review presents a systematic analysis of the material, spanning tire processing methods, aggregate replacement strategies, and the interaction mechanisms across macro-, meso-, and micro-scales. The incorporation of rubber particles (RP) significantly improves energy absorption capacities—specifically toughness, impact resistance, and damping—as well as durability traits such as freeze–thaw and chloride resistance. Mechanistically, RPs act as stress-relieving inclusions that alter crack propagation patterns through bridging and deflection effects. However, the inherent hydrophobicity and low stiffness of rubber create a weak Interfacial Transition Zone (ITZ), characterized by poor bonding and a lack of nucleation sites. This interfacial incompatibility increases the proportion of harmful pores, precipitating a sharp decline in mechanical strength, which remains the material’s primary limitation. To address this, surface modification and synergistic approaches are critically evaluated for their efficacy in enhancing hydrophilicity, promoting mechanical interlocking, and densifying the ITZ. By synthesizing current findings to establish a robust mechanism–performance correlation, this review outlines pivotal future directions, emphasizing nano-enhanced interfaces and data-driven functional design for sustainable infrastructure.