Impacts of corrosion deterioration and loading rates on tensile properties of ultra-high performance fiber-reinforced concrete

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UHPFRC has been widely applied in marine engineering owing to its exceptional durability. However, the coupled effects of corrosion damage and loading rate on the tensile properties of UHPFRC remain incompletely understood, restricting its structural design and safety evaluation in marine environments. This study investigates the tensile performance degradation and microscopic mechanism of UHPFRC under four corrosion degrees and six loading rates (0.1–0.6 mm/min), integrating mercury intrusion porosimetry (MIP)/optical microscopy/scanning electron microscopy (SEM). 72 cubic compressive specimens and 120 valid tensile specimens are adopted. Results reveal that aggravated chloride corrosion continuously increases matrix porosity and fiber deterioration, degrading UHPFRC's mechanical strength. A distinct coupling effect exists between corrosion degree and loading rate. Elevated loading rates produce a dynamic strengthening effect and slightly improve the tensile strength of uncorroded and slightly corroded UHPFRC, whereas high loading rates exacerbate the defect expansion and tensile performance deterioration of moderately and severely corroded specimens. The coupling condition of severe corrosion and low loading rate corresponds to the pseudo-minimal unfavorable combination state with the lowest tensile bearing capacity and ductility. This work clarifies the synergistic deterioration mechanism of corroded UHPFRC under variable loading conditions, providing practical references for the marine application of UHPFRC.