Corrosion deterioration mechanism of fiber-reinforced concrete based on macro- and micro-scale analysis

This study systematically investigated the mechanical response and microstructural characteristics of polypropylene fiber-reinforced concrete with prefabricated cracks under simulated field and laboratory corrosion conditions. Six corrosion scenarios were designed based on a C40 concrete mix. Through mechanical testing, digital image correlation, and microstructural characterization, we found that a polypropylene fiber content of 0.3 wt% markedly enhances compressive strength and suppresses lateral deformation, while excessive fiber content leads to performance deterioration due to increased porosity. Higher corrosion concentrations induced a decline in the elastic modulus, although the fiber network mitigated stiffness degradation. Prefabricated cracks promoted the propagation of mixed-mode I–II fractures, with severe corrosion environments significantly increasing microcrack density and advancing the onset of critical strain zones. Microstructural analysis revealed that SO₄²-/Cl- corrosion decomposes C-S-H gel, generating gypsum, ettringite, and Friedel’s salt. This study provides a multiscale theoretical foundation for the corrosion-resistant design and service-life prediction of support structures in deep mining from both macro- and microscale perspectives.