Fresh and hardened performance of concrete enhanced with graphene nanoplatelets (GNPs)

Abstract

This paper presents an investigation into the fresh and hardened properties of concrete enhanced with graphene nanoplatelets (GNPs). GNP dispersions were prepared using wet dispersion techniques and the influence of various factors on dispersion quality, such as mixing/dispersion methods, sonication time/intensity and GNP concentrations were evaluated. Sedimentation photos and zeta potential analysis were used to assesses the stability of GNP dispersions and determine optimal dispersion conditions for incorporation of GNPs into the concrete specimens. Further, advanced X-ray diffraction (XRD) techniques were used to determine the crystallographic structure of GNPs and a scanning electron microscope (SEM) revealed information about the external morphology (texture), composition and the orientation of the nano materials. Various GNP concentrations were explored including: 0.0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.3 and 0.35 wt % and their effects on workability, apparent density, compressive strength and flexural strength were evaluated. The results suggested that the optimal concentration of GNP was 0.25 wt% which increased compressive and flexural strength of concrete by up to 20.7% and 8.8%, respectively. However, the addition of 0.25 wt% GNPs decreased workability by more than 50% compared to control specimens. Further, apparent density of concrete specimens was not affected by adding GNPs.