Synergistic effects of fiber hybridization on the fracture toughness of seawater sea-sand concrete

This study investigates the fracture behavior of fiber-reinforced seawater sea-sand concrete (FR-SWSSC), focusing on the impact of fiber hybridization on fracture toughness properties and potential synergistic effects. The study employed micro-fibers including short polypropylene (PPS), polyvinyl alcohol (PVA), basalt fibers (BF), and macro-fibers consisting long polypropylene (PPL) and twisted polypropylene (TPPL) fibers. The results indicated that macro-fibers, PPL and TPPL, significantly enhanced the post-peak behavior of SWSSC, increasing fracture energy by 144 % and 93 % respectively, while micro-fibers alone showed negligible impact on the post-peak behavior. Micro-fiber hybridization significantly enhanced both flexural strength and fracture energy of SWSSC, with hybrid PPS/BF and PPS/PVA demonstrated notably improved fracture energy by 176 % and 290 %, respectively, compared to mono PPS. Hybrid combinations of micro/macro-fibers demonstrated a synergistic effect on fracture toughness, where PPL and TPPL fibers bridged larger cracks, activating micro-fibers for enhanced energy dissipation. Moreover, the strong interfacial bond of PVA and BF fibers with the concrete matrix improved macro-fiber bonding strength and overall fracture resistance. By exploring the synergistic effect of hybrid discrete fibers in enhancing the fracture performance of FR-SWSSC, this research promotes sustainable construction practices by addressing inherent challenges of SWSSC.