Preparation of Highly Dispersed Graphene and Its Effect on the Mechanical Properties and Microstructures of Geopolymer
Siyao Guo, Xiao-Li Qiao, Teijun Zhao, Yan-Shuai Wang
Abstract
The dispersibility of graphene is one of the determining factors which affect its efficacy in practice. In the present work, highly dispersed graphene [namely, titanium dioxide (TiO2)-reduced graphene oxide (RGO) nanocomposites] was fabricated by a novel TiO2 intercalation method to the RGO. Such a highly dispersed graphene with a marginal doping amount of the solid aluminosilicate precursors (i.e., 0.01% and 0.02% by weight of geopolymer paste) was used to modify geopolymer pastes. Experimental results showed that such TiO2-RGO nanocomposites can effectively improve mechanical properties of geopolymer matrix, especially the flexural strength, which increased 85%–125% with 0.02% by weight graphene. The graphene enabled the reduction of concentrated stress, which prevents the development of cracks in geopolymer matrix. Compared with the control specimens, the graphene-modified geopolymers are more compact and denser due to the refined pore structures of graphene/geopolymer composites, which is confirmed by the scanning electron microscopy and mercury intrusion porosimetry results.