Research on initial external solution curing technology to enhance durability of cement mortars and chemical deposit infilling mechanism

The improvement of cement concrete curing technology is of great significance for enhancing durability of cement concrete structures then reducing carbon emissions throughout the lifecycle of cement concrete materials. With new insight of adopting the pore blocking curing agent in initial curing water, the proposed initial external solution curing technology is expected to achieve better durability without changing traditional construction process. With initial external solution curing technology, the surface rebound strength of mortar specimens increased about 17.0%, the initial water absorption decreased about 12.5%, the rapid chloride migration coefficient decreased about 22.7%, the carbonation depth decreased about 11.4%, comparing with that of the mortar specimens with water curing. at 28 days curing age. Initial external solution curing technology can promote cement hydration, generate new hydration products to infill micro pores, enhance cement mortar surface performance, and then improve cement mortar durability. The chemical deposit of sodium silicate solution curing was mainly C-S-H gel, and the chemical deposit of sodium bicarbonate was mainly calcium carbonate micro crystal, in initial curing time. Sodium bicarbonate solution curing significantly reduced the content of calcium hydroxide, promoted the generation of calcium carbonate. Compared with water cured mortars, the porosities of mortars cured with sodium silicate solution and sodium bicarbonate solution decreased by an average of 6.1% and 9.2%, respectively. The enhancement ability for pore structure refining of sodium bicarbonate solution was better than sodium silicate solution for mortar specimens. We anticipate our research to provide a new perspective for scientific and technological research on cement concrete surface to enhance structure durability effectively.