Abstract
This study focused on the uniform distribution of graphene oxide (GO) nanosheets in cement composites and their effect on microstructure and performance. For this, three polymer dispersants with different level of polar groups (weak, mild, and strong) poly(acrylamide-methacrylic acid) (PAM), poly(acrylonitrile-hydroxyethyl acrylate) (PAH), and poly(allylamine-acrylamide) (PAA) were used to form intercalation composites with GO nanosheets. The results indicated that GO nanosheets can exist as individual 1–2, 2–5, and 3–8 layers in GO/PAA, GO/PAH, and GO/PAM intercalation composites, respectively. The few-layered (1–2 layers) GO can be uniformly distributed in cement composites and promote the formation of regular-shaped crystals and a compact microstructure. The compressive strengths of the blank, control, GO/PAM, GO/PAH, and GO/PAA cement composites were 55.72, 78.31, 89.75, 116.82, and 128.32 MPa, respectively. Their increase ratios relative to the blank sample were 40.54%, 61.07%, 109.66%, and 130.29%, respectively. Their corresponding flexural strengths were 7.53, 10.85, 12.35, 15.97, and 17.68 MPa, respectively, which correspond to improvements of 44.09%, 64.01%, 112.09%, and 134.79%.
Highlights
Graphene oxide (GO), a derivative of graphene, inherits the structural and propertyrelated features of graphene such as a large surface area and high strength, and exhibits unique properties such as the presence of a large number of oxygen-rich functional groups and good hydrophilicit [1,2] The unique structure and properties of GO give it potential for use in improving the mechanical properties and durability of cement composites
The results indicated that the polycarboxylate superplasticizers (PCs) and polyacrylate cannot uniformly distribute GO in cement composites with few layers by forming composites due to their poor intercalation with GO nanosheets, and the resulting cement composites have an uneven and porous microstructure
The results indicated that forming grafting copolymers of PCs and polyacrylate with GO would obviously decrease the number of active groups on the nanosheets and, their ability to control the cement microstructure [36]
Summary
Graphene oxide (GO), a derivative of graphene, inherits the structural and propertyrelated features of graphene such as a large surface area and high strength, and exhibits unique properties such as the presence of a large number of oxygen-rich functional groups and good hydrophilicit [1,2] The unique structure and properties of GO give it potential for use in improving the mechanical properties and durability of cement composites. The cement hydration crystals often distribute and grow unevenly in the cement composites, forming large interfacial gaps and cracks This occurs primarily because GO nanosheets aggregate re-stacking in suspensions and cement composites due to large-area π–π interactions and strong Van der Waals interactions between graphene oxide layers [32]. Our goal is to prepare GO nanosheets made up of only a few layers and uniformly distribute them in an aqueous suspension solution by forming GO/dispersant intercalation composites. Through doping the GO/dispersant intercalation composites in cement composites, we aim to distribute GO nanosheets uniformly and individually in cement composites to form compact, uniform microstructures throughout the materials, improving their performance. For convenience of analysis and discussion, S1, S2, S3, S4, and S5 are used to represent the blank and control samples, and the GO/PAM/cement, GO/PAH/cement, and GO/PAA/cement composites, respectively
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