From Graphene Oxide to Reduced Graphene Oxide: Impact on the Physiochemical and Mechanical Properties of Graphene–Cement Composites

Abstract

Graphene materials have been extensively explored and successfully used to improve performances of cement composites. These formulations were mainly optimized based on different dosages of graphene additives, but with lack of understanding of how other parameters such as surface chemistry, size, charge, and defects of graphene structures could impact the physiochemical and mechanical properties of the final material. This paper presents the first experimental study to evaluate the influence of oxygen functional groups of graphene and defectiveness of graphene structures on the axial tension and compression properties of graphene-cement mortar composites. A series of reduced graphene oxide (rGO) samples with different levels of oxygen groups (high, mild, and low) were prepared by the reduction of graphene oxide (GO) using different concentrations of hydrazine (wt %, 0.1, 0.15, 0.2, 0.3, and 0.4%) and different reduction times (5, 10, 15, 30, and 60 min) and were added to cement mortar composites at an optimal dosage of 0.1%. A series of characterization methods including scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared spectroscopy were performed to determine the distribution and mixing of the prepared rGO in the cement matrix and were correlated with the observed mechanical properties of rGO-cement mortar composites. The measurement of the axial tension and compression properties revealed that the oxygen level of rGO additives has a significant influence on the mechanical properties of cement composites. An addition of 0.1% rGO prepared by 15 min reduction and 0.2% (wt %) hydrazine with mild level of oxygen groups resulted in a maximum enhancement of 45.0 and 83.7%, respectively, in the 28-day tensile and compressive strengths in comparison with the plain cement mortar and were higher compared to the composite prepared with GO (37.5 and 77.7%, respectively). These results indicate that there is a strong influence of the level of oxygen groups and crystallinity of graphene structures on the physiochemical and mechanical properties. The influence of these two parameters are interconnected and their careful balancing is required to provide an optimum level of oxygen groups on rGO sheets to ensure that there is sufficient bonding between the calcium silicate hydrate (C-S-H) components in the cement matrix and minimum level of defects and higher crystallinity of graphene structures, which will improve the mechanical properties of the composite. Finding the optimized balance between these two parameters is required to formulate graphene cement composites with the highest performance.

Two‐Dimensional Layered Metallic VSe2/SWCNTs/rGO Based Ternary Hybrid Materials for High Performance Energy Storage Applications

“…Other characteristic peaks are those at 1712 cm −1 (C=O stretching due to carboxyl groups), at around 1600 cm −1 ( due to C=C bonds), and peaks at 1110 and 1043 cm −1 , which correspond to C−O stretching vibrations . In comparison with GO, the disappearance of peaks at 1712, 1100 and 1043 cm −1 and the appearance of peaks at 1640 cm −1 (C=C) and 2935 cm −1 (C−H stretching) in the VSR 1 sample corroborate the successful reduction of GO in the composite . Although VSe 2 and its composites produce similar XRD patterns, they are completely distinct from each other with respect to their morphologies.…”

Advancing fabrication and properties of three-dimensional graphene–alginate scaffolds for application in neural tissue engineering

“…The absence of the characteristic peak of graphite at $26 and the existence of the GO peak at 9.88 validates the oxidation of graphite. 28 Morphology and structure of fabricated graphene-based composite scaffolds Fig. 3a-c displays the sponge-like feature of fabricated graphene composite aerogels with low density.…”

Structural Applications of Thermal Insulation Alkali Activated Materials with Reduced Graphene Oxide

“…Nanomaterials have been widely applied in concrete to improve its mechanical performance [40][41][42][43]. Particularly, reduced graphene oxide (rGO) is used in construction for its large specific surface area, favorable mechanical strength, and high toughness [44][45][46][47]. In addition to this superior performance, rGO can effectively disperse in the highly alkaline environment of AAMs matrix (pH~12.5) due to electrostatic stabilization and significantly improve its mechanical properties [48][49][50].…”