Study on the effect of non-metallic fibers on mechanical properties of high-strength mortar for marine structure applications

Abstract

This study evaluates the effect of non-metallic fibers on the mechanical and physical properties of high-strength mortar (HSM) for marine structure applications. In the context of global infrastructure development facing challenges of superior load-bearing capacity, long lifespan, and resilience in harsh environmental conditions, HSM emerges as a key material due to its impressive compressive strength, superior durability, and excellent impermeability. However, the inherent brittleness of HSM, especially in corrosive marine environments characterized by chloride and sulfate ion ingress, wave erosion, and freeze-thaw cycles, poses significant risks. Reinforcement with fibers has been widely studied to mitigate this brittleness. While metallic fibers like steel fibers are highly effective in enhancing mechanical properties, their susceptibility to corrosion in marine environments can degrade their load-bearing capacity and accelerate structural deterioration. Therefore, this research focuses on non-metallic fibers (polypropylene (PP), polyvinyl alcohol (PVA), glass fiber (GF), basalt fiber (BF), carbon fiber (CF)), which offer excellent corrosion resistance, low specific gravity, non-conductivity, and good chemical resistance. The primary objective is to comprehensively assess the influence of both discrete non-metallic fibers and non-metallic fiber meshes on critical mechanical and physical properties of HSM, including compressive strength, flexural tensile strength, elastic modulus, impermeability, post-cracking behavior, energy absorption capacity, and crack control mechanism, with samples designed for marine applications. The results indicate that the addition of PP fibers generally reduced the slump flow, compressive strength, and flexural strength of HSM. Specifically, increasing PP fiber content from 0% to 0.5% initially increased slump flow, but further increases beyond 0.5% tended to decrease it. The bulk density of the samples ranged from 2223 to 2432 kg/m³. Non-metallic fiber contents of 0.25% and above significantly reduced both compressive and flexural strength, reflecting the disruption of the concrete matrix structure and the creation of micropores. Nevertheless, PP fibers contribute to ductility enhancement and improved crack resistance, particularly when combined with steel fibers. An optimal fiber content below 0.5% is suggested. These findings provide a solid scientific basis and reliable experimental data for the effective and sustainable design and application of HSM in marine structures, enhancing crack resistance and shrinkage control.