Development and Performance Evaluation of a Composite Silicate-Based High-Penetration Surface Treatment Agent for Portland Cement Concrete

Abstract Silicate-based surface treatment agents are sustainable materials that provide protective effects on the surface of portland cement concrete, consequently improving the long-term durability of concrete infrastructures. This study proposed a composite silicate-based surface treatment agent for concrete. The original proportion included lithium silicate and potassium silicate as main agents, with lithium sulfate, urea, organosilicon polyether surfactant, and fluorocarbon surfactant as additives. Additionally, dimethyl sulfoxide (DMSO) was incorporated to further enhance the penetrability of the treatment agent. The performance of the optimized material was assessed by testing the penetration depth, rebound value, freeze-thaw resistance, water impermeability, and carbonation resistance of the treated concrete samples with different strength grades. Furthermore, the influence of the treatment on the pore structures of concrete was investigated through nuclear magnetic resonance and scanning electron microscopy. The results showed that DMSO effectively improved the penetration performance of the treatment agent, achieving a penetration depth of 6.8 mm at a content of 1.5%. Compared to the original proportion, the optimized proportion exhibited significant advantages in surface hardness, freeze-thaw resistance, water impermeability, and carbonation resistance, indicating enhanced protective effects on the concrete. Pore characteristics analyses revealed that the improved protective effects involved a larger reduction of the porosity in the surface layer of concrete. The addition of DMSO improved the penetrability of the treatment agent, facilitating the reaction between the silicates and portlandite, which further contributed to the blocking effect. This work offers an effective approach for developing high-penetration silicate-based treatments for portland cement concrete.