Recovered Tire-Derived Aggregates for Thermally Insulating Lightweight Mortars

This study explores the innovative use of recovered tire-derived aggregates in cement-based mortars to enhance thermal insulation and reduce environmental impact. The research addresses the pressing global challenge of managing end-of-life tires (ELTs), which are non-biodegradable and contribute significantly to waste management issues. By incorporating crumb rubber from recycled tires into mortars, this study investigates the feasibility of creating lightweight, thermally insulating mortars suitable for building repair and rehabilitation. The primary objective is to develop mortars that minimize structural load, decrease energy consumption in buildings, and promote the recycling of ELTs as a valuable resource. The study focuses on evaluating how varying crumb rubber content affects key properties such as workability, thermal conductivity, compressive strength, and fracture energy. Experimental tests were conducted to assess these properties, with the results indicating that mortars with up to 50% crumb rubber content exhibit improved thermal insulation and meet industry standards for non-structural repair applications. The methodology involved creating eight different mortar mixtures with varying proportions of crumb rubber particles (ranging from 0% to 100%). Each mixture was tested for physical and mechanical properties, including density, workability, air content, setting time, thermal conductivity, and strength. The experimental results showed that as the crumb rubber content increased, the thermal conductivity of the mortars decreased, indicating enhanced insulation properties. However, higher crumb rubber content led to reduced mechanical strength, highlighting the need for a balanced approach in material design. Key findings reveal that the air content of early-age mortar paste increases linearly with the crumb rubber replacement ratio, impacting the hardened behavior by concentrating stresses or facilitating the infiltration of damaging elements. The study also establishes relationships between mortar properties and crumb rubber content, contributing to the development of sustainable construction materials. The environmental benefits of recycling ELTs are emphasized, as this practice reduces the reliance on natural sand, a resource that is the second most consumed globally after water. This study underscores the viability of using crumb rubber from recycled tires in mortars for repair and rehabilitation purposes. The developed mortars, particularly those with 25% to 50% crumb rubber content, show promise as non-structural repair products, offering improved thermal insulation and reduced environmental impact.