Molecular dynamics study of temperature and defects on mechanical properties of Gr(GO)/C-S-H composites

Abstract

In this paper, the effects of temperature and different defect types on the interfacial properties, kinetic properties and mechanical properties of Gr(GO)/C-S-H composites were investigated by molecular dynamics. It is shown that the incorporation of graphene (Gr) and graphene oxide (GO) improves the mechanical properties of the calcium silicate hydrate (C-S-H) model to varying degrees. The presence of defects at different temperatures affects the ordering of oxygen (Ow) in water in the proximal range of interlayer Ca ions and can effectively influence the spatial correlation between interlayer Ca ions and oxygen (Oc) in functional groups. The bond lengths of some Caw-Oc at different temperatures can be modulated by defects, thus affecting the interaction between calcium ions and graphene oxide. Compared with Gr/GO and C-S-H composites in perfect state, the incorporation of defects slows down the rate of C atoms, which can effectively enhance the interfacial connection. At temperatures of 100K-300 K, the effect of defect type on Gr/GO and C-S-H composites is small and the mobility of H atoms did not change significantly. Whereas, at high temperatures 400 K and 500 K, the presence of defects gives higher mobility of H atoms, which affects the properties of the composites. The tensile strength (compressive strength) and Young's modulus of Gr(GO)/C-S-H composites at perfect and different defect types basically show a decreasing trend with increasing temperature. The system structure changes during the relaxation process because of the different defect types and Gr (GO), which make the initial structure different, and thus the mechanical properties change.