Preparation and mechanism of graphene oxide/isobutyltriethoxysilane composite emulsion and its effects on waterproof performance of concrete

In the present paper, graphene oxide (GO) was used to modify isobutyltriethoxysilane. GO/isobutyltriethoxysilane composite emulsion was then prepared by the sol-gel method. The properties of the obtained composite emulsion were characterized by Fourier Transform Infrared (FT-IR), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS). The waterproof performance of GO/isobutyltriethoxysilane composite emulsion was studied by capillary water absorption and water contact angle experiments. The FT-IR results showed that the number of Si-O bonds in the composite emulsion were superior to that in silane emulsion while carboxyl groups were found to be less. This indicated that GO was successfully grafted to the isobutyltriethoxysilane monomer. The XPS data showed that amounts of C-OH in the composite emulsion were lower than those in silane emulsion, suggesting that part of C-OH in the composite emulsion participated in formation of Si-O-C covalent bond between GO and silane. SEM and EDS revealed that the composite emulsion and silane emulsion could form a dense hydrophobic layer on the concrete surface, thereby achieving waterproof effect. Water contact angle and capillary water absorption tests of concrete indicated composite emulsion with significantly improved waterproof performances when compared to silane emulsion. (C) 2019 Elsevier Ltd. All rights reserved.