Effect of Hybrid Fiber on the Chloride Salt Erosion Resistance of Shotcrete

The use of shotcrete is a critical support technique in ocean engineering structures. However, it often exhibits low chloride and salt erosion resistance under ocean environmental conditions and poor long-term durability. This study employed polypropylene fiber (PF) and basalt fiber (BF) to optimize the shotcrete mix design. Laboratory immersion and salt spray tests simulated chloride ion corrosion environments in the ocean's underwater and atmospheric zones. The effects of different corrosion mechanisms and varying fiber volume fractions on shotcrete strength and durability were then analyzed. The results indicate that shotcrete demonstrates strong resistance to chloride-induced corrosion in both ocean underwater and atmospheric zones when the volume fractions of PF and BF are 0.2% and 0.1%, respectively. Based on test results from 3D digital microscopy (3D-DM), X-ray diffraction (XRD), and scanning electron microscopy (SEM), the chloride-induced degradation mechanism of hybrid fiber-reinforced shotcrete was analyzed from both mesoscopic and microscopic perspectives. This study offers theoretical support for applying hybrid fiber-reinforced shotcrete in ocean engineering environments.