The effect of woven glass and carbon fiber reinforcements on the mechanical behaviour of cementitious composites

This study investigates the impact of fiber reinforcement, specifically carbon and glass fibers, on the flexural behavior and fracture performance of cementitious composites with varying strengths The strength grades of the composites were designated as high-strength, medium-strength, and low-strength. The composites were reinforced with woven glass and carbon fibers at different length/span ratios and subjected to flexural testing to evaluate key parameters such as strength, strain, and modulus. High, medium, and low-strength prism specimens were prepared using specific cement dosages (634.26 kg/m 3 for high strength, 535.26 kg/m 3 for medium strength, and 432.65 kg/m 3 for low strength) with corresponding water-to-cement ratios of 0.3, 0.4, and 0.65, respectively. The results indicate that fiber reinforcement significantly enhances the flexural properties of all composite categories, with the most notable improvements observed in the medium-strength and high-strength composites. Among the composites, the carbon fiber-reinforced high-strength composite (HS-CFRC-4/7) demonstrated the highest flexural strength (10.00 MPa), a 73% improvement over the control specimen. However, a diminishing return in strength gain was observed in high-strength composites, suggesting weaker anchorage bond between woven fiber and the specimen where the matrix strength becomes the dominant factor. Additionally, carbon fibers exhibited a higher strain capacity than glass fibers, with consistent increases in ductility across all composite groups. Fracture analysis revealed distinct failure modes, including flexural cracks, diagonal shear cracks, and delamination, especially in high-strength composites.