Heterogeneous Nature of Calcium Silicate Hydrate（C-S-H） Gel:A Molecular Dynamics Study
来源期刊：Journal Of Wuhan University Of Technology Materials Science Edition2020年第2期
论文作者：金书成 LI Jinhui 徐文远 DING Qingjun
文章页码：435 - 440
摘 要：Structure and mechanical properties of Calcium silicate hydrate （C-S-H） at a molecular level act as "DNA" of cement-based construction materials.In order to understand loading resistance capability of C-S-H gel,research on molecular dynamics （MD） was carried out to simulate the uniaxial tension test on C-S-H model along x,y,and z directions.Due to the structure and dynamic differences of the layered structure,the C-S-H model demonstrates heterogeneous mechanical behavior.On an XY plane,the cohesive force can reach 4 GPa,which is mainly provided by the Ca-O and Si-O ionic-covalent bonds.The good plasticity of calcium silicate sheet is attributed to the silicate branch structure formation and the recovery role of interlayer calcium atoms.However,in z direction,C-S-H layers connected by the unstable H-bonds network,have the weakest tensile strength 2.2 GPa.This results in the brittle failure mode in z direction.The relatively low tensile strength and poor plasticity in z direction provides molecular insights into the tensile weakness of cement materials at macro-level.
金书成1，LI Jinhui2，徐文远1，DING Qingjun2
1. School of Civil Engineering, Northeast Forestry University2. School of Materials Science and Engineering,Wuhan University of Technology
摘 要：Structure and mechanical properties of Calcium silicate hydrate （C-S-H） at a molecular level act as "DNA" of cement-based construction materials.In order to understand loading resistance capability of C-S-H gel,research on molecular dynamics （MD） was carried out to simulate the uniaxial tension test on C-S-H model along x,y,and z directions.Due to the structure and dynamic differences of the layered structure,the C-S-H model demonstrates heterogeneous mechanical behavior.On an XY plane,the cohesive force can reach 4 GPa,which is mainly provided by the Ca-O and Si-O ionic-covalent bonds.The good plasticity of calcium silicate sheet is attributed to the silicate branch structure formation and the recovery role of interlayer calcium atoms.However,in z direction,C-S-H layers connected by the unstable H-bonds network,have the weakest tensile strength 2.2 GPa.This results in the brittle failure mode in z direction.The relatively low tensile strength and poor plasticity in z direction provides molecular insights into the tensile weakness of cement materials at macro-level.
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