Effect of citric-acid-modified chitosan (CAMC) on hydration kinetics of tricalcium silicate (C3S)

Studying the mechanism by which organic admixtures affect the hydration and dissolution of tricalcium silicate (C 3 S) reveals the effect of organic admixtures on ordinary Portland cement and enables target regulation of cement-based materials. In this study, the effects of citric-acid-modified chitosan (CAMC) on the hydration exotherm, hydration products, and microscopic morphology of C 3 S were investigated. The interface structures, ion adsorptions, and dissolution properties of CAMC and C 3 S were analyzed using a molecular dynamics simulation method. The results showed the presence of an attraction between the C 3 S surface and CAMC due to the existence of O p -H w , O p -Ca s , and H p -O w ion pairs. CAMC adsorbed most of the Ca ions released upon dissolution of C 3 S in the aqueous solution and the resulting pairs exhibited low solubilities. The Ca ions were located on the surfaces of C 3 S particles, preventing the dissolution of the particles and proving the interference effect of additives on the hydration of the cement silicate phase.