Improving the mechanical performance of concrete by graphene nanoplatelets (GNP) enrichment in the interfacial transition zone (ITZ)

Abstract

The interfacial transition zone (ITZ) between the aggregates and cementitious paste is generally a weak spot in concrete. To address this deficiency, the graphene nanoplatelets (GNP) are adopted and a novel approach is proposed in this study. Initially, GNP with three different diameters of 2 μm, 4 μm and 7 μm are evaluated. The 2 μm GNP are selected for the best strength and microstructure improvement in cementitious composites. Subsequently, the concrete made of GNP-precoated aggregate is prepared. The SEM and EDS are used to evaluate the microstructure and elementary composition of its ITZ. This research demonstrates that GNP-precoated aggregate approach significantly improves the efficacy of GNP in concrete by enhancing the ITZ. GNP promote the formation of calcium silicate hydrate (C–S–H) while concurrently mitigating the production of calcium hydroxide (CH) in ITZ, leading to enhanced elemental distribution and compactness of ITZ, as well as a reduced ITZ thickness. The proposed method notably enhances the mechanical properties of concrete.