Synergistic mechanism of silica fume polystyrene particle concrete against sulfate attack and chloride ion penetration

Abstract Polystyrene particle (EPS) concrete is a lightweight thermal insulation material with significant potential for applications in building energy conservation and specialized structures. However, its durability is limited under corrosive conditions, such as in saline-alkali soils and marine environments, which restricts its engineering use. This study systematically investigates how silica fume (SF) enhances the resistance of EPS concrete to sulfate attack and chloride ion penetration. The results show that adding SF significantly improves both sulfate resistance and reduces chloride permeability in EPS concrete, with optimal performance observed at a 10% SF dosage. At this ratio, after 360 sulfate wet–dry cycles, the EPS concrete exhibits a compressive strength retention rate 149.5% higher than that of the control group, and a mass loss rate 67.6% lower. Additionally, its chloride migration coefficient decreases by 89.6%, reaching an ‘extremely low’ performance level. Micromechanical analysis indicates that silica fume optimizes the microstructure through a synergistic mechanism involving physical filling, chemical inhibition, and interfacial strengthening. This combined effect consumes the reactants responsible for the formation of expansive corrosion products and significantly enhances the density and mechanical performance of the interfacial transition zone. This study provides a theoretical foundation for the development and application of highly durable lightweight concrete in demanding environments such as marine engineering and saline-alkali regions.