Molecular dynamic simulation on the anisotropic tensile properties of the calcium silicate hydrate enhanced by graphene oxide

SJ Lu and WQ Chen and Y Gao and J Zhang and ZY Zhang and ZR Xiang, JOURNAL OF MATERIALS SCIENCE, 59, 21362-21376 (2024).

DOI: 10.1007/s10853-024-10448-3

Benefiting from its superior mechanical properties, abundant oxygen- containing functional groups and ultrahigh specific surface area, graphene oxide (GO) can effectively strengthen cement-based materials. However, the calcium silicate hydrate (C-S-H), as the most significant binding phase in cement, has apparent anisotropy characteristics. The enhancement of GO on the tensile performance of C-S-H in different directions requires to be revealed. Hence, in this work, the molecular dynamic simulation was applied to study the influence of GO in different directions on the tensile properties of C-S-H composites and the corresponding reinforcing mechanisms. The results demonstrate that the GO nanosheets incorporated in parallel water layers can reinforce the ductility of C-S-H, with the tensile strain energy density increasing up to about 43.9%. The structural characteristics demonstrate that the GO nanosheets incorporated in parallel water layers significantly change the C-S-H failure mode, whose initial failure diffuses from the GO surface. By contrast, the failure mode of plain C-S-H composites is diffused from the high-stress zone. Nevertheless, when GO nanosheets are incorporated in the vertical water layer direction, the destruction form of the C-S-H composite changes little, with the tensile strain energy density only increasing by 11.9%. The energy evolution characteristics verify that the external work of GO nanosheets added in the parallel water layer is increased by about 53.4%, about 2.4 times higher than that of GO nanosheets added in the vertical water layer. The findings of the study not only promote boarder understanding of GO-reinforced cementitious composite but also assist nanomodification cement design in the future.

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