Molecular insight into the influence of temperature and salt ion concentration on the formation of CaCO3 clusters in C-S-H gel
Shaojie Guan, Te Liang, Xuefu Zhang, Jiachuan Ran, Dongshuai Hou, Shiyang Liu, Xiangge Chen
Abstract
The deposition and adsorption phenomena of sparingly soluble salts are common in underground infrastructure, severely affecting drainage efficiency and causing structural blockages. The nucleation and growth mechanisms of calcium carbonate (CaCO 3 ) clusters within C-S-H gel pores under various temperatures and concentration conditions are investigated in this study using molecular dynamics simulations. The results indicated that elevated temperatures accelerate particle motion and prenucleation, which significantly enhance the nucleation and aggregation rates of CaCO 3 . At low concentrations, stable coordination bonds and hydrogen bonding facilitate the adsorption of cluster ions on the C-S-H surface. At high concentrations, increased ionic interactions and limited of adsorption sites on the C-S-H matrix surface lead to ionic bonding between small clusters, promoting the formation of larger clusters. The bonding strength of Ca-O c and Ca w -O c increased with increasing temperatures and decreasing concentrations, contributing to the stability of the clusters. The increase in temperature and concentration accelerated hydrogen bond breakage, promoting the formation of CaCO 3 clusters. This study revealed the significant effect of temperature and concentration on the nucleation and growth of CaCO 3 clusters within C-S-H gel pores. These findings provide a scientific basis for the development of new anti-decalcification cement materials that are crucial for enhancing the durability and stability of underground infrastructure.