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

Abstract

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 cementbased 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 Ca 2+ released by cement particles, thereby reducing the concentration of Ca 2+ 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.

Defoaming and Toughening Effects of Highly Dispersed Graphene Oxide Modified by Amphoteric Polycarboxylate Superplasticizer on Oil Well Cement

“…As a nano-reinforcing material used in various engineering matrixes, the large specific surface area, high modulus, and reactivity of GO make it a promising material for enhancing the toughness of cement [ 4 , 5 ] and concrete composites [ 6 ]. More importantly, GO can disperse in water due to its plentiful oxygenated hydrophilic functional groups, thereby accelerating the hydration process of cement and forming effective interfacial bonds between hydration products [ 7 ]. During the hydration process, GO sheets can act as active sites to accelerate the deposition and growth of hydrated crystals, thus providing GO-reinforced cements with good mechanical properties [ 8 , 9 ].…”

Effects of Hybrid Graphene Oxide-Nanosilica on Calcium Silicate Hydrate in the Simulation Environment and Cement

“…Nanomaterials such as nano-CaCO 3 , nano-SiO 2 , carbon nanotubes, carbon nanofibers, and graphene oxide (GO) have been widely used to ameliorate the properties of cement composites. − However, due to their tiny surface area, zero-dimensional nanomaterials, which are highly reactive and can produce calcium silicate hydrate (C-S-H) gels by reacting with Ca­(OH) 2 , are unable to prevent crack extension or provide enough nucleation sites for the growing of cement hydrates . Carbon nanotubes, which are a one-dimensional substance, can prevent crack extension in cement matrix composites and have a considerable crack bridging effect.…”

“… 1 − 4 However, due to their tiny surface area, zero-dimensional nanomaterials, which are highly reactive and can produce calcium silicate hydrate (C-S-H) gels by reacting with Ca(OH) 2 , are unable to prevent crack extension or provide enough nucleation sites for the growing of cement hydrates. 5 Carbon nanotubes, which are a one-dimensional substance, can prevent crack extension in cement matrix composites and have a considerable crack bridging effect. Even with the use of effective dispersants and ultrasonic treatments, it is challenging to disperse because of the strong van der Waals forces.…”