Molecular dynamics simulation of the interfacial interaction mechanism between functional groups on graphene-based two-dimensional matrix and calcium silicate hydrate

Abstract

It has been proved that the incorporation of graphene (G) -based two-dimensional (2D) materials can improve the mechanical and durability performance of cementitious matrix to varying degrees. However, there is not a clear understanding of the nano-scale interaction mechanism between the matrix and 2D materials, as well as its correlations with the improvement efficiency. By the molecular dynamics simulation, this work simulated the growth process of C-S-H gel on 2D matrix with different functional groups, investigated interfacial interaction between C-S-H gel and 2D materials, and revealed the underlying reinforcement mechanism. The results show that C-S-H gel tend to nucleate on the surface of graphene oxide (GO) and functionalized graphene oxide (FGO) due to strong attractions of hydroxyl and silanol groups. As a consequence, C-S-H particles are regularly packed on the surface of GO and FGO, with diameters ranging from 3 nm to 5 nm, consistent with the CM-II model. Furthermore, the ranking with regards to the interfacial bonding strength is FGO > GO≫G. It is attributed to the high-strength Ca-O and Si-O connections formed on the C-S-H/FGO interface, which can contribute to a greater enhancement efficiency of 2D materials. The mechanism interpreted here may optimize the application of graphene-based materials on the cementitious matrix.