Cyclic flexural performance of seawater sea-sand concrete reinforced with hybrid fibers

Abstract

Fiber-reinforced seawater sea-sand concrete (FR-SWSSC), a sustainable alternative to traditional concrete, requires evaluation of its flexural performance under cyclic loading, critical for coastal and marine structures experiencing repeated loads. This study investigated the effect of fiber hybridization and its potential synergistic effects on the cyclic flexural behavior of FR-SWSSC. Incremental cyclic loading was employed for testing FR-SWSSC specimens in four-point cyclic bending. This investigation employed micro-fibers—polypropylene (PPS), polyvinyl alcohol (PVA), basalt (BF)—and macro-fibers—long polypropylene (PPL) and twisted polypropylene (TPPL)—to explore the synergistic influence of fiber size and type (synthetic and natural) on the cyclic flexural behavior. Hybrid-fiber reinforcements were incorporated in two configurations: micro-fibers only and a combination of micro- and macro-fibers. This approach facilitated the evaluation of size-dependent synergy on cyclic flexural properties. According to the results, micro/macro-fiber hybridization significantly improved performance during large deflection cycles. Hybrid TPPL/PVA exhibited 105 % and 664 % greater energy dissipation compared to mono TPPL and PVA, respectively. Similarly, PPS/PVA hybrids displayed a 79 % and 112 % increase in hysteretic damping ratio, over mono PVA and PPS fibers, respectively and reduced damage index and improved strength degradation at large deflections compared to mono fibers. This improvement was attributed to enhanced bonding strength of TPPL or PPS by the strong chemical bonding strength of PVA fibers, which strengthened the surrounding concrete matrix and allowed for a greater contribution from the hybrid components. This study addresses a knowledge gap and paves the way for improved material development through the utilization of a potential sustainable alternative concrete. • The study assessed the cyclic flexural performance of SWSSC reinforced with hybrid fibers. • Hybrid fiber reinforcement significantly enhanced the flexural performance of SWSSC under cyclic loading conditions. • Chemically bonding micro-fibers strengthened the concrete matrix and enhanced macro-fiber adhesion. • The complementary effects of hybrid fibers countered the limitations typical of individual fiber types.

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