Abstract
In this study, the effects of graphene oxide (GO) on the microstructure of cement mortars were studied using scanning electron microscopy (SEM), thermogravimetric (TG), and X-ray diffraction (XRD) techniques. Cement mortar samples with different proportions of GO (0.02, 0.04, 0.06, and 0.08 wt % based on the weight of cement) were prepared. The test results showed that GO affected the crystallization of cement hydration products, C–S–H (calcium silicate hydrate is the main hydrate product) and CH (calcium hydroxide). The morphology of hydration products changed with the increase of GO content. Furthermore, the results of XRD analyses showed that the diffraction peak intensity and the crystal grain size of CH (001), (100), (101), and (102) for GO samples increased considerably compared with the control sample. Based on the results, it can be understood that GO can modify the crystal surface of CH, leading to the formation of larger crystals.
Highlights
Graphene oxide (GO) is one of the graphene derivatives, which basically consists of a several layers of wrinkled two-dimensional carbon sheet with various oxygen-containing functional groups such as hydroxyl, carboxyl, and epoxy groups on its surface and/or between the inter-sheet layers [1]
The results indicated that graphene oxide (GO) significantly improved the mechanical properties of cement mortar, with the greater effect on the early age strengths
Some studies reported that the enhanced mechanism of GO in cement composites is similar to what has been observed in the cement composites with carbon nanotubes (CNTs)
Summary
Graphene oxide (GO) is one of the graphene derivatives, which basically consists of a several layers of wrinkled two-dimensional carbon sheet with various oxygen-containing functional groups such as hydroxyl, carboxyl, and epoxy groups on its surface and/or between the inter-sheet layers [1]. Zhu et al [8] investigated the influences of GO on hydration progress and microstructure of alkali-activated slag (AAS) cementitious material. They found that increasing GO content could reduce the fluidity of AAS mortar due to the large surface area of GO. GO reduced the setting time and fluidity of MKPC due to the large surface area They reported that GO (0.05 wt %) modified MKPC with denser microstructure showed better mechanical strength, which was attributed to the “filler effect” and good mechanical performances of GO. The influence mechanism of GO on cement hydration was revealed using the following test methods: X-ray diffraction (XRD), thermogravimetric (TG), and scanning electron microscopy (SEM) observations
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