In situ fabrication and characterization of graphene/geopolymer composites

Homogeneously dispersed graphene reinforced geopolymer composites were easily and simply prepared through in-situ reduction of graphene oxide (GO) in alkaline geopolymeric solutions. The in-situ GO reduction degree, microstructure and mechanical properties of reduced graphene oxide (rGO)/geopolymer composites were investigated systematically. The results revealed that the rGO C/O ratio increased dramatically after in situ reaction at 60 degrees C for 72 h in geopolymeric solutions. The reduction is mainly attributed to conversion of C=O to C-O bonds and then elimination of residual oxygen-function groups under the alkaline conditions. The as-obtained rGO was uniformly dispersed and exhibited good long-term stability in the geopolymeric solutions. The final amorphous geopolymer matrix structure was unaffected by the homogeneously dispersed rGO yet strong interfacial bonding was observed. As a result, the fracture toughness of the composite with 1 wt% rGO was improved by similar to 17% compared with the pristine geopolymer. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.