Upcycling End-of-Life Tire Rubber into Polymer Composites: A Critical Review of Binder Chemistry, Granulometry, Performance Trade-Offs and Sustainability

End-of-life tire rubber offers a secondary feedstock for polymer-bound construction products, but sustainable use depends on performance, durability and life-cycle impacts. This critical narrative review compares epoxy, polyurethane, unsaturated polyester and phenolic/novolac systems while distinguishing direct polymer–rubber experiments from adjacent evidence. Binder chemistry, rubber gradation, dosage basis and processing jointly control the reported strength–deformation response; no universally optimal matrix or particle-size distribution emerges. Selected polyurethane–rubber formulations exhibit large apparent compressive strains, highlighting deformation capacity alongside strength. These machine-displacement-based measurements do not establish cyclic damping or elastic recovery. Acid-exposure studies of epoxy microconcretes support the durability potential of polymer matrices, although chemical resistance must be verified separately for rubber-containing formulations. Surface treatment can improve stiffness while reducing tensile strength, and thermal stability does not establish fire performance. Contrasting life-cycle studies show that waste incorporation alone does not guarantee lower environmental burdens. The synthesis links sustainable development to resource conservation, validated service performance, durability and reduced replacement demand, assessed over equivalent functional units and service lives. Study-level comparisons and a material-selection framework identify priorities for independent replication, comparable reporting and product-specific environmental and safety testing.