Graphene Oxide – A New Potential Nano Reinforcement

Abstract

Graphene oxide (GO) is a new potential nano reinforcement in cementitious composites. In previous research, graphene oxide has shown promising potential for improving mechanical properties, and particularly the tensile strength capacity. The thesis investigates the effect of GO on fresh cement mortar (workability, air content, heat of hydration), microstructure (SEM & EDS) and mechanical strength (Flexural -, compressive -, splitting tensile strength) after 3,7, and 28 days of curing. These properties are studied by introducing various dosages of GO combined with a constant content of polycarboxylate (SP). The selected dosages of GO are 0.03 wt%, 0.05 wt%, and 0.2 wt% of the cement weight. The effects of two different types of GO have been studied: Water dispersed- and fine powder concentrate GO. The results show that the workability decreases correspondingly to the increasing content of water dispersed GO. The heat of hydration is increased for both types of GO which indicate a chemical reaction between GO and cement. The percent air content is almost constant with a GO dosage of 0.03 wt% and 0.05 wt%, but is increased from 3.2 % to 4.9 % with 0.2 wt% water dispersed GO. The increased air content is an indirect outcome of poor compaction and workability. The adverse effects of GO on fresh mortar will consequently influence the mechanical properties. GO has the potential of accelerating the hydration process and enhance the early mechanical strength (3 and 7 days), but has no effect after 28 days of curing. Particularly for the highest content of water dispersed GO, the adverse effect on the workability seems to diminish the mechanical strength after 28 days. No distinct influence of GO on the microstructure has been observed with SEM, except for the presence of GO sheets verified by EDS.