Full process of calcium silicate hydrate decalcification: Molecular structure, dynamics, and mechanical properties. (November 2022)

• Record Type: Journal Article
• Authors: Zhang, Yu; Guo, Le; Shi, Jinyan; Luo, Qi; Jiang, Jinyang; Hou, Dongshuai
• Is Part Of: Cement and concrete research. Volume 161(2022)
• Publication Date: 2022-11
• Subjects: C-S-H gel -- Decalcification -- Molecular dynamics -- Bound water -- Lamellar mineral; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2022.106964
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: C-S-H gel is the origin of cohesion of cement and deteriorates with decalcification. However, the molecular process underlying its complex chemical reactions and structure/properties evolution is mostly unexplored. Herein, the influence of decalcification on calcium silicate hydrate (C-S-H) is studied by molecular dynamics and experiments. The results show, during the decalcification, the transformation of C-S-H molecular structure from lamellar crystal into cross-linked glassy structure, transformation from bound water into -OH groups, and transformation of dynamics characteristics from lattice vibration at fixed sites into diffusion, which would be exacerbated by the dissociation of intralayer calcium. Mechanically, for both nano and micro/macro scale, tensile property of C-S-H depends on interlayer bonding and so is weakest at complete dissociation of interlayer calcium, whereas compressive property decreases continuously with decalcification. The interlayer bonding basically determines the threshold of micro/macro mechanical properties of C-S-H gel. This study provides a well example for molecular-scale exploration of the full process of aluminosilicate mineral dissolution.