Performance analysis of cement-based sandwich composites with fiber-reinforced skins and rubberized concrete core from waste tire recycling.

This article focuses on the development and characterization of cement-based sandwich composites (SCs) featuring a rubberized cementitious core made from 70% rubber powder and 30% rubber granules derived from waste tires, combined with fiber-reinforced mortar skins incorporating short glass fibers (GF) or nanoclay-treated recycled carbon microfibers (rCF). The SCs achieved lightweight concrete densities (1745–1781 kg/m³) suitable for semi-structural applications and demonstrated enhanced flexural strength (up to 195% increase over rubberized core alone) and impact energy absorption (up to 270% higher than reference mortars). Thermal testing showed that fiber-reinforced skins improved residual strength after high-temperature exposure, although the overall thermal stability was limited by degradation of the rubberized core; SCs also exhibited reduced thermal conductivity due to interfacial delamination disrupting heat transfer. Scanning electron microscopy revealed stronger fiber-matrix bonding for rCF but identified interfacial microcracking between core and skins, highlighting the need for improved skin-core adhesion and optimized fiber dispersion to fully realize the composites’ structural potential.