Effect of the Oxygen Content of Graphene on the Mechanical Properties of Cement-Based Composites.

Recent research indicates the possibility of using nanomaterials (carbon nanotubes, graphene, titanium oxide, nanosilica, and nanoalumina) in civil infrastructure applications; however, costly process and low production of such materials may limit such applications [1]. Introduction of nanomaterials in cement paste reduces the porosity and rate of hydration leading to the development of stronger and more durable products [2]. The high surface area of these materials makes them efficient in controlling the propagation of microcracks in cementitious composite materials. It is demonstrated that graphene and graphene oxide may reduce the brittleness and enhance toughness, tensile and flexural strength of the hydrated cement composite [2]. An improvement of the properties of cement can be achieved only if the graphene is well dispersed in the matrix. Thus, it becomes necessary to disperse graphene in the water used for the preparation of the cement. The dispersion plays a key role in standardizing the properties of graphene-based composites, and has been extensively studied [3,4]. However, in most of the cases graphene is dispersed through the use of an organic surfactant which can create problems at the level of the interface between cement and graphene. Graphene oxide (GO), which have many polar groups on the surface, does not require the surfactant to obtain a good dispersion and also presents a higher interaction with the cement matrix. Indeed, a polar surface improves both the dispersion in water and the interaction between cement and graphene, leading theoretically to better mechanical properties.