Investigation on the re-agglomeration of graphene nanoplatelets in cement composites using X-ray computed tomography

This paper presents the results of X-ray computed tomography (XCT) analysis on the size and distribution of graphene nanoplatelets (GNPs) in hardened mortar. GNP dosages of 0.035, 0.07 and 0.1 wt% were adopted. The results indicated that re-agglomeration degree increased with increasing GNP loading. The most
significant re-agglomeration was observed at 0.1 wt% dosage, which formed slender flake-like morphology with a lateral size of ~ 249 μm. Microstructural analysis indicated that the well-dispersed GNPs could function as nucleation sites to promote hydration, while the re-agglomerated GNPs which formed large size plates introduced weak zones at the graphene-matrix interface. The compression test results complied well with the microstructural analysis, showing the optimal GNP dosage of 0.07 wt% increased compressive strength by 19% compared to plain mortar.