Research on Durability Evolution of Concrete in Sulfuric Acid Corrosion Environment

Sulfuric acid corrosion is a non-negligible problem affecting the durability of concrete materials. To explore the mechanism of sulfuric acid corrosion on the fracture performance and microstructure of concrete, three-point bending test was utilized to analyze the evolutionary characteristics of the crack mouth opening displacement and the fracture toughness of concrete corroded by sulfuric acid. Scanning electron microscope and energy-dispersive spectrometer were utilized to analyze the characteristics of microscopic morphology and corrosion products of concrete corroded by sulfuric acid. The result shows that the fracture evolution of concrete can be divided into four stages: nonlinear development stage, linear development stage, deceleration expansion stage, and accelerated expansion stage. In purified water environment, the peak fracture load and fracture toughness of concrete is positively related to corrosion time. In sulfuric acid corrosion environment, the peak fracture load and fracture toughness of concrete are negatively related to corrosion time and concentrations of sulfuric acid solution. Microscopic experiments show that the interior of concrete is less affected by sulfuric acid corrosion, and the structure is relatively dense compared with the surface. The expansion crystal ettringite formed at the fracture surface of the concrete specimen during sulfuric acid corrosion was the main reason for the durability reduction of concrete.