Effects of Alkali–Silica Reaction on Ion Erosion in Granite-Manufactured Sand Concrete

To address potential durability issues in granite-manufactured sand concrete affected by alkali–silica reaction (ASR) under sulfate or chloride ion environments, admixtures such as fly ash, silica fume, slag, alumina, and aluminum hydroxide were selected. An ASR-ion erosion experiment was designed with compressive strength, dynamic elastic modulus, and electric flux as key indicators, assessing the impact of rock types, and single and combined admixtures on concrete’s ion penetration resistance. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were used to investigate deterioration mechanisms under sulfate exposure. The experiments show that ASR accelerates the rate of compressive strength loss and decreases the dynamic elastic modulus of granite-manufactured sand concrete under sulfate attack. Additionally, ASR reduces the electric flux, thereby enhancing the concrete’s resistance to chloride ion penetration. Fly ash effectively mitigated compressive strength loss, slag slowed the reduction in dynamic elastic modulus, and the combination of slag and aluminum hydroxide significantly reduced dynamic elastic modulus loss. Additionally, the combination of slag and alumina enhanced sulfate resistance.