Engineering properties of strain-hardening geopolymer composites reinforced with various natural fibers: Multiscale synergistic optimization and sustainability

Achieving a synergistic optimization of material cost, environmental sustainability, and mechanical performance presents a significant challenge in the development of EGC, owing to the high cost and non-degradability of commonly used polyethylene (PE) fibers in EGC. This study comprehensively investigated the feasibility of replacing PE fibers with natural fibers (NF) to develop EGC with superior mechanical properties, cost-effectiveness and environmental sustainability, with a special focus on the effects of three NF types (jute, ramie, and coconut fibers) on mechanical properties, fiber-matrix interface behavior and microstructure of EGC. X-ray computed tomography (XCT) and backscattered electron microscopy (BSEM) were employed to analyze the internal microstructure, including pore structure and fiber distribution. Results indicate that the EGC mix showed pronounced strain-hardening and multiple cracking behavior when 0.5 % PE fiber was replaced with NF, attributed to the improved fiber-matrix interfacial properties and enhanced fiber distribution. EGC with 0.5 % jute fiber outperformed other hybrid fiber reinforced mixes in terms of compressive strength (85.4 MPa), tensile strength (6.6 MPa) and tensile strain capacity (6.5 %), comparable to those of single fiber reinforced mixes. The material cost, embodied carbon and embodied energy of EGC with NF were decreased by up to 73 %, 5 % and 26 %, respectively, as compared to EGC with solely PE fibers. This study provides a potential pathway for developing high-strength, cost-effective, and environmentally friendly green building materials, expanding the application of NF-EGC to address complex environmental demands.