▎ 摘　　要

Due to its high aspect ratio and outstanding tensile strength, graphene oxide (GO) can dramatically reduce the brittleness of cement-based materials. In this paper, GO nanosheets were successfully synthesised using the modified Hummers' method. Effects of the GO on the fluidity, mechanical properties of alkali-activated slag (AAS) mortars and the microstructure of the AAS pastes were studied. It is found that addition of the GO caused a significant reduction in fluidity and a slight decrease in the compressive strength of the hardened mortars. However, the GO improved the flexural strengths by 20% with a dosage of 0.01 wt% after 7 days. Large-scale layered double hydroxides (LDHs) were observed using SEM, the compositions of which were identified and EDS and XRD. A possible mechanism of the formation of LDHs in the GO-AAS system is proposed. Due to the Mg2+/Al3+ decomposed from the slag and the Al (OH)(4)(-) formed in the high pH condition in the GO-AAS system, the reaction pathway of LDHs can be regarded as aMg(2+) + Al(OH)(4)(-) + (2a - 2)OH- + xH(2)O + A(-) reversible arrow MgaAl(OH)(2+2a)A center dot xH(2)O(s) This research provides a further understanding of the effect of graphene oxide which has a potential application of GO in AASC. (C) 2016 Elsevier Ltd. All rights reserved.