Use of graphene oxide nanosheets to regulate the microstructure of hardened cement paste to increase its strength and toughness

Graphene oxide (GO) nanosheets are prepared by oxidation of graphite followed by sonication exfoliation. FTIR and AFM results indicate that the GO nanosheets have a thickness of about 6 nm, and that the GO surface is covered with oxygenated groups (-OH, -O-, -COOH and -SO3H). Hardened cement pastes containing different proportions of the GO nanosheets are prepared, and it is found that the GO formed both flower-like and polyhedron-like crystals, with these effects increasing as the GO content increases from 0.01% to 0.06% by weight of the cement. The compressive strength and toughness of the corresponding hardened cement paste are found to be markedly increased compared to a control sample. The results suggest that the GO nanosheets can control the crystalline form and assembly of the cement hydration products. A formation mechanism for regular hydration crystals is proposed, based on the experimental results. This research indicates significant potential for the practical application of GO nanosheets in the preparation of cement-based materials of high strength and durability.