Evaluating the physico-mechanical performance of cement mortar reinforced with metakaolin/graphene oxide dual nano-additives

Researchers interested in producing high-mechanical-performance cement-based structures follow many strategies to achieve this purpose; one of these is the dual addition of materials. The current study was used thermal activation and chemical exfoliation to successfully prepare nano-metakaolin (NMK), whereas Hummers’ traditional technique was followed to prepare graphene oxide (GO). The key aim of this investigation was to promote the mechanical performance of cement mortars by incorporating both NMK and GO in the same matrix, where very few studies have examined the usage of both NMK and GO in the same cement matrix. For this purpose, six groups of plain and blended mortars were cast, with the cement being partially replaced with 10% NMK and GO being added at ratios of 0.01–0.04 wt.% of cement. The pore size distribution of the prepared mortars was studied using the nitrogen adsorption method, while phase composition/decomposition analysis was recognized by TGA and XRD. The microstructure was investigated by SEM. The obtained results revealed a great enhancement of splitting tensile strength by about 71% and about 20% for compressive strength, in addition to the refinement of the pore structure and promotion of the hydration reaction as confirmed by XRD, TGA, and SEM analysis.