Effects of triethanolamine modified graphene oxide on calcium silicate hydrate in synthesized system and cement composite

Graphene oxide (GO) has been used as an ideal admixture in cement composite because of the remarkable properties. However, the complicated system of cementitious materials limits the investigations on the reinforcing mechanism of GO. As the main hydration product, calcium silicate hydrate (C-S-H) determines the mechanical performance of cement composite, and research on the reaction between GO and C-S-H is of much importance for clarifying the reinforcing mechanism of GO. In this study, triethanolamine-graphene oxide (TEA-GO) was synthesized to improve the dispersion of GO in pore solution. And the impacts of GO and TEA-GO on the properties of C-S-H in the synthesized system and cement were comprehensively investigated by Si-29 MAS-NMR, SEM, FTIR and nano-indentation. In the synthesized C-S-H system, the well-dispersed TEA-GO accelerated the deposition and growth of C-S-H on nano-sheets. The improvement in the polymerization of synthesized C-S-H was also found. When TEA-GO was incorporated in cement, the interfacial bonding strength of TEA-GO with the matrix was enhanced and a large amount of high-density C-S-H formed in TEA-GO/cement composite. The refined microstructure of C-S-H and ameliorated interfacial bonding are promising to improve the mechanical properties of TEA-GO/cement composite because of the efficient cracking-bridging and load transfer.