Calcium silicate hydrate colloid at different humidities: Microstructure, deformation mechanism, and mechanical properties

CY Liang and Q Zheng and JY Jiang and PJM Monteiro and SF Li, ACTA MATERIALIA, 228, 117740 (2022).

DOI: 10.1016/j.actamat.2022.117740

Calcium silicate hydrate (C-S-H) is the main hydration product of Portland cement, while fundamental questions persist regarding its colloidal structure and water content. In this work, we developed a full atomistic C-S-H colloid model and investigated the physical and mechanical properties at different gel water concentrations. Water confined in nanometer gel pores degrades the mechanical properties of C-S -H because of its hydrolysis effect. A "ductile to brittle" transition was observed in the C-S-H colloid model with increasing gel water contents, evolving from transgranular failure to intergranular fracture. The gel water confined in nanometer-sized pores displays glassy characteristics, and it acts as a lubricant and facilitates structure distortions during the deformation. We elucidated the topology effect of the hydrogen bond network on the evolution of the viscoelasticity of C-S-H at different humidities. This work sheds light on the role of water in C-S-H colloids from nanostructure perspectives.(c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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