The interaction of graphene oxide with cement mortar: implications on reinforcing mechanisms

A comprehensive insight into the interactions between cementitious matrices and graphene oxide (GO) remains critical to the understanding of fundamental factors, such as reinforcing mechanisms, governing the engineering performance of cement composites. Herein, for the first time, this study investigated the snubbing effect on the interaction of GO in cement mortar. Molecular dynamic (MD) simulations were performed to pull out GO sheets from the mortar matrix from different angles. Simulation results showed that the increase in pull-out angle led to up to a fourfold increase in the bridging stress of GO, which confirmed the critical role that the snubbing effect played on the reinforcing mechanism of GO. To further understand the snubbing effects, interactions between GO and mortar matrix were analysed from both physical and chemical perspectives, showing the increase in bridging stress caused by pull-out angles is mainly attributed to the enhanced mechanical interlocking and the facilitated formation of interfacial bonds. Based on these findings, an analytical model was developed to quantify the key parameters of the snubbing effects, including snubbing coefficient, adhesion band, friction and strain-hardening coefficient, which guides design inputs of GO-reinforced cementitious composites. Graphical abstract: [Figure not available: see fulltext.]