Abstract
This paper evaluated the effect of graphene oxide/graphene (GO/GR) hybrid on mechanical properties of cement mortar. The underlying mechanism was also investigated. In the GO/GR hybrid, GO was expected to act as a dispersant for GR while GR was used as reinforcement in mortar due to its excellent mechanical properties. For the mortar specimen, flexural and compressive strength were measured at varied GO to GR ratios of 1:0, 3:1, 1:1, 1:3, and 0:1 by keeping the total amount of GO and GR constant. The underlying mechanism was investigated through the dispersibility of GR, heat releasing characteristics during hydration, and porosity of mortar. The results showed that GO/GR hybrid significantly enhanced the flexural and compressive strength of cement mortars. The flexural strength reached maximum at GO:GR = 1:1, where the enhancement level was up to 23.04% (28 days) when compared to mortar prepared with only GO, and up to 15.63% (7 days) when compared to mortar prepared with only GR. In terms of compressive strength, the enhancement level for GO:GR = 3:1 was up to 21.10% (3 days) when compared with that of mortar incorporating GO only. The enhancement in compressive strength with mortar at GO:GR = 1:1 was up to 14.69% (7-day) when compared with mortar incorporating GR only. In addition to dispersibility, the compressive strength was also influenced by other factors, such as the degree of hydration, porosity, and pore size distribution of mortar, which made the mortars perform best at different ages.
Highlights
Cementitious materials are the most widely used construction materials worldwide [1]
Wang [7] reported that the flexural strength of GR-cement composite showed a more remarkable increase when compared to the compressive strength
Graphene oxide (GO) and GR hybrid was used as an additive in cement mortar to improve the dispersion of GR in mortar and to improve the mechanical properties of mortar
Summary
Cementitious materials are the most widely used construction materials worldwide [1]. Cao et al [9] observed that by adding GR at 0.02 wt% by weight of cement, the enhancement in flexural and compressive strength at 28 days was up to 32.0% and 20.3%, respectively. It is reported that the further increase in mechanical properties is difficult which may be due to decreased tensile strength of GO when compared with GR owing to the breakage of carbon chains by functional groups [19,20]. Hong et al [23] found that the incorporation of GO greatly enhances the aqueous dispersion of a robust Cu2O nano-catalyst From these studies, it can be speculated that GO might act as dispersant to improve the dispersibility of GR in water, so that the excellent mechanical properties of GR can be utilized to further enhance the crack resistance of cement-based materials. The work in this research explored the new role of nano-materials in the application of cementitious materials
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