Enhanced Mechanical and Microstructural Properties of Eco-friendly Cementitious Composites Reinforced with Treated Natural Fibers and Nano-graphene Oxide

To improve mechanical and microstructural performance, this study develops a sustainable nano-engineered cementitious composite reinforced with alkali-treated natural fibers and nano-graphene oxide (nano-GO). Bagasse pulp and recycled coir fibers were used as environmentally friendly reinforcements, while nano-GO served as the nano-modifier to promote matrix hydration, densification, and fracture resistance. Single-fiber tensile testing and thermogravimetric analysis confirmed that alkali (NaOH) surface modification of coir fibers at varying concentrations significantly enhanced tensile strength, Young’s modulus, thermal stability, and fiber–matrix interfacial adhesion. A laboratory-scale Hatschek technique was employed to fabricate composite boards with treated fiber concentrations ranging from 5 to 15 wt.%. According to three-point bending test results, treated fiber-nano-GO composites exhibited significantly higher flexural strength and ductility than untreated systems. With a flexural strength of 11.82 MPa, the optimal formulation with 5 wt.% treated coir fiber, 19 wt.% bagasse pulp, and 0.5 wt.% nano-GO exceeded conventional fiber-cement performance standards. Microstructural investigation confirmed improved load transfer, enhanced fiber–matrix bonding, and reduced microcracking due to synergistic nano-reinforcement effects. These results demonstrate a resource-efficient and sustainable approach for producing high-performance cementitious materials enabled by nanotechnology, appropriate for durable and cost-effective construction in developing countries.