Abstract
Original graphene oxide (GO) nanosheets were prepared using the Hummers method and found to easily aggregate in aqueous and cement composites. Using carboxymethyl chitosan (CCS) as a dispersant, few-layered GO nanosheets (1–2 layers) were obtained by forming CCS/GO intercalation composites. The testing results indicated that the few-layered GO nanosheets could uniformly spread, both in aqueous and cement composites. The cement composites were prepared with GO dosages of 0.03%, 0.05% and 0.07% and we found that they had a compact microstructure in the whole volume. A special feature was determined, namely that the microstructures consisted of regular-shaped crystals created by self-crosslinking. The X-ray diffraction (XRD) results indicated that there was a higher number of cement hydration crystals in GO/cement composites. Meanwhile, we also found that partially-amorphous Calcium-Silicate-Hydrate (C-S-H) gel turned into monoclinic crystals. At 28 days, the GO/cement composites reached the maximum compressive and flexural strengths at a 0.05% dosage. These strengths were 176.64 and 31.67 MPa and, compared with control samples, their increased ratios were 64.87% and 149.73%, respectively. Durability parameters, such as penetration, freeze-thaw, carbonation, drying-shrinkage value and pore structure, showed marked improvement. The results indicated that it is possible to obtain cement composites with a compact microstructure and with high performances by introducing CCS/GO intercalation composites.
Highlights
Cement composites have been used for over 2000 years, while Portland cement was discovered nearly 200 years ago and has been used ever since [1,2]
The results showed that grafting a polymer onto graphene oxide (GO) nanosheets would decrease active groups on the GO nanosheets resulting in reducing the template effects, the control capacity for cement hydration products [42]
We investigated the effects of GO nanosheets on cement composites by incorporating carboxymethyl chitosan (CCS)/GO composites into the cement paste and the mortar, separately
Summary
Cement composites have been used for over 2000 years, while Portland cement was discovered nearly 200 years ago and has been used ever since [1,2]. Previous studies showed that graphene oxide (GO) nanosheets can promote the formation of regular-shaped cement hydration products and an even-compact microstructure Both of these have a repairing effect on cracks and pores, resulting in improved strength and durability [27,28,29]. Though researchers have varying opinions on the reinforcing function of GO nanosheets [34], the common consensus is that GO can, as a nano additive, have filling, interlocking and bridgings functions between cracks and pores in cement composites and that it can promote the formation of a compact microstructure in them while visibly improving mechanical strength and durability [35,36,37,38,39]. Our research results contribute to the preparation of high-performance cement composites through the few-layered GO nanosheet based formation of a compact and even microstructure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
