Deterioration Mechanism and Constitutive Model of BFRC Corroded by Acid Rain

To elucidate the long-term degradation mechanism of basalt-fiber-reinforced concrete (BFRC) subjected to acid rain corrosion, this study conducted mechanical tests on BFRC specimens with a fiber content of 0.15% under simulated acid rain (pH = 3.0) over 0–120 corrosion cycles. Results reveal a nonlinear evolution in both compressive and splitting tensile strengths—an initial decrease, subsequent increase, and final gradual decline—with peak values attained at 60 and 30 cycles, respectively, corresponding to maximum enhancements of 20% and 45% relative to the initial strength. Microstructural analyses (SEM-EDS) identify a three-phase deterioration process: chemical dissolution (surface decalcification), competitive pore filling coupled with C-S-H decalcification, and expansive cracking induced by ettringite formation. Integrating the experimental data and degradation mechanisms with maturity theory, a dynamic constitutive model incorporating corrosion cycles is developed. The model accurately predicts the time-dependent mechanical degradation of BFRC under acid rain exposure, providing a theoretical foundation for durability design and assessment of fiber-reinforced concrete in corrosive environments.