Pore structure evolution and chloride ion permeability of concrete under sulfuric acid

Underground reinforced concrete pipelines experience structural degradation due to external high-frequency fatigue loads and internal corrosive environments. This study investigates the effects of prolonged sulfuric acid attack on concrete specimens, focusing on mass loss, volume loss, surface roughness, corrosion depth, and chloride ion permeability. Corrosion depth measurements reveal a linear increase over time, while surface roughness, analysed using three-dimensional (3D) laser scanning, increases linearly with corrosion time at a rate of 0.0084 mm/day. The chloride ion diffusion coefficients exhibit a non-linear trend, ranging from 0.02 to 17.49 × 10−12 m2/s. Increased porosity and enhanced permeability accelerate structural degradation. By integrating advanced techniques such as 3D scanning and X-ray fluorescence for microscale analysis, this study provides novel insights into concrete deterioration. The findings offer practical guidance for designing protective coatings and improving the durability of pipelines in acidic environments.