Dispersion and Reinforcement Mechanism of Graphene Oxide in Cement-Based Materials

To investigate the dispersion behavior of graphene oxide (GO) in cement-based materials and its reinforcement mechanism, the dispersion stability of GO in simulated cement pore solution (calcium hydroxide solution) and the anti-flocculation effect of different dispersants, as well as the influence of GO on the fluidity and mechanical properties of cement mortar, were systematically studied. GO was synthesized by a modified Hummers method, and its functional groups and morphology were characterized using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The improvement in dispersibility of GO in alkaline environment by polycarboxylate superplasticizer (PC) was quantitatively evaluated using UV-Vis spectrophotometry. The results show that PC can effectively prevent the agglomeration of GO in alkaline environment. Compared with the reference group without GO, the 28 d compressive and flexural strengths of cement mortar containing 0.03% GO increased by 21.37% and 39.62%, respectively. Based on an analysis combining observations of microstructural morphology using a scanning electron microscope (SEM) and finite element simulations, a possible mechanism of action is proposed: GO nanosheets exert a “shielding effect” that prevents the propagation of microcracks in the cement paste, thereby enhancing the strength of cement-based materials.