Effect of GO nanosheets on shapes of cement hydration crystals and their formation process

The effects of graphene oxide (GO) nanosheets with different sizes and dosages on cement hydration crystal shapes and the mechanical strength of cement paste are investigated. It is found that flower-like crystals are more prominent at low GO dosage (<0.03%) and polyhedral or lamellar crystals at high dosage (>0.03%). The flexural and compressive strengths of cement paste with smaller GO nanosheets are clearly improved. Formation processes for hydration crystals are proposed based on scanning electron microscopy images. GO nanosheets can promote assembly of flower-like and polyhedral structures from rodlike crystals, with the ultimate formation of a dense structure. (C) 2014 Elsevier Ltd. All rights reserved.