A potential sustainable way for iron tailings sand in cast-in-situ concrete subjected to sulfate-chloride attack: performance and mechanisms

This study employed iron tailings sand (ITS) at different replacement ratios (0%, 25%, 50%) to substitute river sand in the preparation of iron tailings sand cast-in-situ concrete (ITS-CISC). Through macroscopic performance tests and microstructural characterization, the effects of ITS content on the performance of concrete in distilled water, sulfate, and sulfate-chloride corrosion environments are systematically investigated. Results show that after 180 days of sulfate and sulfate-chloride corrosion, incorporating 25% ITS increases the compressive strength of concrete by 8.69% and 6.22%, respectively. Sulfate-chloride corrosion aggravates the deterioration of concrete. At 180 days, the compressive strength of specimens with 25% ITS content in the sulfate-chloride environment is 7.53% and 26.67% lower than that in the sulfate and distilled water environments, respectively. In sulfate and sulfate-chloride environments, ITS enhances mechanical interlocking between particles and promotes the formation of hydration products, thereby increasing the compactness of the interfacial transition zone.