RILEM Webinar: Tricalcium Silicate Hydration and Calcium Silicate Hydrate Formation

We are pleased to announce that the next ROC&TOK in Chinese webinar will take place on Thursday, February 24th, 2022 at 7:30 PM Beijing time and will be one hour long (30-minute presentation + 30-minute interaction). The registration for this webinar is free.

Speaker: Prof. Zongjin Li, from University of Macao, China
Host: Dr. Pan Feng, Southeast University, China

Title: Tricalcium Silicate Hydration and Calcium Silicate Hydrate Formation Mechanism Revealing Using Ab Initio Method

Understanding the hydration mechanisms of tricalcium silicate (C3S) and formation process of calcium silicate hydrate (C-S-H) is fundamental in concrete technology, which can help the modification of the materials structure of concrete at nano meter scale and subsequently improving the mechanical properties and durability of concrete. In this study, we provide an exhaustive atomic insight into the C3S hydration and C-S-H formation by first-principles calculations. First, we introduce the background of C3S hydration and basic characterization of C-S-H. Then, the adsorption mechanism of water on the C3S surface is revealed from first-principles calculations. We find the adsorption energy increases with the increase of electron transfer at water/C3S interface and strength of total Ca-Ow bonds. Next, we discuss the feasibility of the calcium silicate aqua complexes as C-S-H precursors using ab initio metadynamics simulations. We discover two kinds of calcium silicate aqua complexes, [Ca(H2O)n(SiO2(OH)2)] and [Ca(H2O)n(SiO(OH)3)]+, which have six and five stable states on the free energy surface (FES), respectively and different ligand substitution mechanisms. Moreover, an ab initio mechanism for tricalcium silicate dissolution was unraveled. Finally, the water adsorption, proton exchange and diffusion of water into the surface layer accelerate the leaching of calcium ions from the surface step by step have been investigated.