Effects of graphene oxide on fluidity of cement paste and structure and properties of hardened cement paste

Graphene oxide( GO) nanophase dispersion was prepared by Hummers method followed ultrasonication. The effects of GO on fluidity of cement pastes and microstructure of hardened cement paste were studied. The microstructure of GO and hardened cement paste were characterized by FT-IR,AFM,XRD and SEM. The tested results showed that the fluidity of cement paste with GO would reduce. And the study also found a 0. 01% increase in the dosage of GO should increase 0. 02% of polycarboxylate superplasticizer( PCs) in order to keep the fluidity more than 200 mm within3 h. Meanwhile,the results also showed that the microstructure of hardened cement hydrate have changed obviously with the addition of GO. When GO / PCs dosage was 0. 01% /0. 24%-0. 03% /0. 28%,there are lots of flower-like microcrystals with distribution evenly in the hardened cement paste at hydration age of 7 d. When GO / PCs dosage was 0.05% /0. 32%-0. 07% /0. 36%,there are many lamellae shaped crystals in the hardened cement paste at 7 d. And the hardened cement paste showed dense trend with hydration age extended to 28 d. The results suggested that GO can ragulate the microstructure of cement hydration products and have excellent reinforcing and toughening effects,which has a significance for the improvement of the strength and toughness of cement based composites.