Effect of graphene oxide–treated textile waste cotton and polyester fibers on fresh, mechanical, thermal and durability properties of cement mortar

The incorporation of waste textile fibers into mortar has recently gained attention as a sustainable approach, yet untreated textile fibers often reduce workability, mechanical and durability properties due to poor interfacial bonding between the fiber and the cement matrix. This study investigates the effect of Graphene Oxide (GO)–treated waste cotton and polyester fibers on the fresh, mechanical, thermal and durability performance of cement mortar. The hybrid fiber-reinforced mortar was prepared with a cement-sand ratio of 1:2.25 (by weight) in two phases. In Phase 1, the polyester fiber content was kept constant at 0.10%, while varying the cotton fiber content: 0%, 0.05%, 0.10%, 0.15%, 0.20% and 0.25% (by weight). In Phase 2, the cotton fiber content was kept constant at 0.10%, and varying the polyester fiber content: 0%, 0.05%, 0.10%, 0.15%, 0.20% and 0.25% (by weight). The cotton and polyester fibers were pre-treated by dispersing them in a 10 mg/l GO solution prior to mixing. The workability, compressive and flexural strength, thermal performance, acid and alkali resistances, and microstructural evolution of GO-treated fiber-reinforced mortars were tested. The mixture, containing 0.1% polyester and 0.25% cotton fibers, demonstrated the best overall performance, achieving 19% and 22% improvements in compressive and flexural strength, respectively, 73% improvements in thermal insulation, and a 43% improvement in acid resistance compared with the conventional mortar. The presence of oxygen-containing functional groups in GO enhanced fiber–matrix adhesion and the formation of Calcium Silicate Hydrate (C–S–H) near the interface between the fibers and cement matrix, leading to superior microstructural integrity and durability. The results demonstrate the synergistic benefits of hybrid GO-treated waste cotton and polyester fibers in cement mortar, providing an effective pathway for reusing of textile waste while simultaneously improving mechanical, durability and thermal performance of the mortar. • GO-treated cotton and polyester fibers were incorporated into cement mortar using a two-phase hybrid design approach. • The optimum mix (0.25% cotton + 0.10% polyester) improved compressive and flexural strength by 19% and 22%, respectively. • Thermal insulation and acid resistance increased by 73% and 43%, with only a marginal (∼11%) loss in workability. • GO treatment enhanced fiber hydrophilicity, interfacial bonding, and C–S–H formation at the fiber–matrix interface. • An effective and sustainable pathway for high-volume recycling of waste textile fibers in cementitious composites.