Impact of crumb rubber on the performance of unsaturated polyester-dune sand mortar

Polymer mortars have attracted immense interest as effective and rapid repair materials in the modern construction industry owing to their advantages over conventional Portland cement mortar. Various types of polymer binders, such as unsaturated polyester resin (UPR), have been used in polymer mortar owing to their low cost, excellent strength, high workability, and rapid curing. However, the brittleness of Unsaturated polyester resin mortar (UPRM) limits its applications in construction. Herein, we investigated the feasibility of reutilizing locally available industrial crumb rubber (CR) (CR, <0.8 mm) waste in the production of UPR/dune sand (DS) (DS, 100–600 μm) mortars with reduced environmental impact for repair applications. Polymer mortars were prepared by replacing 3, 5, 7, and 10 wt% DS aggregates with CR in 60/40 DS/UPR mortar formulations. The mortars provided superior ductility and comparable durability compared with the control mix. Furthermore, the inclusion of CR decreased thermal conductivity, thereby improving insulation ability. Although replacing CR degraded the mechanical strength, the mortar still met the workable standards for repair applications. The inclusion of CR further decreased the density of the mortar (1475–1800 kg/m³) rendering it suitable for lightweight concrete applications. These findings support the use of CR in polymer mortar and demonstrate its potential benefits in the construction industry.