Multi-scale analysis of the strengthening mechanism of functionalized graphene as reinforcement in cement composites

This paper explored the impact of graphene oxides used as cement composites reinforcing materials on the mechanical properties of samples. In the direct method, graphene oxide (GO) was incorporated into the mortar in different dosages, and two GOs (GO-C and GO-N, with carboxyl and amino groups respectively) greatly improved the mechanical performance of mortar. The test results show that GO promoted the hydration process, hydration products can grow on the surface of GO and GO interspersed in the matrix playing the role of riveting, filled the internal holes and cracks of mortar. In the indirect method, GO was used as the film coating onto the surface of the polyethylene fiber (PE). The flexural strength of mortar with GO-C and GO-N coated fiber is increased by 17.24 % and 13.79 %, respectively. While GO-C, GO-N and PE samples increased by 12.07 %, 8.62 % and 10.35 %. GO coated is stronger than the samples using plain PE fiber and GO alone. The SEM indicated that the roughness of fibers was modified by the wrinkled GO surface and GO film modified the bond between fiber and matrix. Molecular dynamics simulation (MD) was employed to analyze the interfacial adsorption characteristics. MD results showed that the interaction between GO-C/C-S-H is 3.03 times of GO-N/C-S-H, GO-C can help matrix to bear more load and GO-C has a higher enhancement than that of GO-N. Anyhow, increasing the bonding and reaction of GO/matrix is crucial to the development of cement-based materials, and efficiently functionalized GO is the focus of future development.