Catalysis and Regulation of Graphene Oxide on Hydration Properties and Microstructure of Cement-Based Materials

Graphene oxide (GO) is a two-dimensional material that adds functionalized oxygen-containing groups on the surface of graphene through strong acid oxidation. The oxygen-containing functional groups on the surface make GO have good dispersion and surface activity. When GO is incorporated into cement-based materials, while providing nucleation sites for cement hydration, it can also react with ions released by cement hydration. Therefore, GO has a catalytic effect on the hydration process of cement and plays a role in regulating the morphology of the hydration products, which in turn affects the formation of the microstructure of cement-based materials. In this study, the catalytic and regulatory effects of GO on the hydration characteristics, pore structure, and internal interface of cement-based materials are reviewed. The analysis shows that the oxygen-containing functional groups on the surface of GO can absorb a large number of water molecules, promote the dissolution of cement particles in water, and adsorb the Ca2+ released by cement particles, thereby reducing the concentration of Ca2+ around the cement particles and shortening the induction period of cement hydration. In addition, GO can provide more nucleation sites for cement hydration and shorten the hydration acceleration period. GO promotes the formation of hydration products through the nucleation effect and gradually transforms needle-like and rod-like hydration products into flower-like or polyhedral-like crystals. In addition, GO optimizes the pore structure of cement-based materials when it affects cement hydration and the morphology of hydration products through the above-mentioned effects. In addition, it makes the connection between hydration products closer through the bridging effect, so that the total porosity of cement-based materials decreases, gel-pore content increases, capillary-pore content decreases, and pore structure is significantly optimized. Finally, while optimizing the pore structure of cement-based materials, GO has an obvious optimization effect on the interface transition zone (ITZ) of cement-based materials, which significantly reduces the ITZ width and increases the ITZ density.