Evaluating Polyurethane Concrete under Varying Temperature Conditions: Advancing Sustainable and Resilient Railway Joint Materials

High-temperature arching in longitudinal slab track expansion joints compromises track smoothness and safety, demanding innovative materials that accommodate slab deformation while meeting structural requirements. This study evaluated polyurethane concrete (PUC) as a sustainable alternative to traditional cement-based joints by investigating its mechanical properties and mesoscopic failure behavior across temperatures. Two reactive PUC types were compared with ordinary portland cement concrete (OPC-60) in terms of strength, elastic modulus, and elongation at break. Mesoscale analyses revealed fracture propagation patterns and three-dimensional (3D) contact force distributions under stress. Results indicate that reactive polyurethanes enter glass transition at 56.8°C and 68.1°C, reducing molecular chain binding and thus mechanical strength. Coarse aggregates enhance transverse contact strength, improving compressive resistance despite localized fractures. Crucially, PUC maintains its low modulus and high strain capacity while remaining undamaged at high temperatures, ensuring deformation resistance under extreme loads. By extending service life, reducing repairs, and minimizing resource use, PUC offers an ecoefficient solution for durable railway infrastructure.