Assessing the combination of graphene and graphene oxide nanosheets in cement-based materials

Graphene (Gr) and Graphene Oxide (GO) are graphene-based nanosheet (GNS) materials with ultrahigh mechanical properties. The addition of Gr/GO (from 0.01 % to 2 % in mass) to a cement-based material can significantly enhance its mechanical properties. GO has higher efficiency than Gr, but it is more costly. In this paper, a Gr-GO solution was developed by combining Gr and GO in water. The compressive strengths of the samples with and without Gr-GO were determined. Deep analyses were performed by applying several imaging techniques such as nano-tomography, SEM, and confocal Raman imaging to exploit the correlation between microstructural properties and mechanical properties and durability of cement-based materials. The micro- structural properties were also quantified from the 3D images obtained by nano-tomography. The results showed that the GNS-added sample had a higher porosity (about 12.4 %) than that of the reference sample (about 6.1 %) but the GNS-added sample had a more homogeneous distribution of micropores. Raman imaging results explained the formation of hydration product and acceleration of hydration rate by Gr-GO in GNS-added samples. The mechanical properties showed that the addition of 0.03 % Gr-GO could increase the compressive strength of mortar samples by 28 %.