The mechanics of carbon-based nanomaterials as cement reinforcement — A critical review

This review attempts to organize and critique recent forays in using carbon-based nanomaterials as cement and concrete reinforcement. Most carbon-based nanoreinforcers show significantly improved flexural and compressive strength (> 100 %) and increased durability (> 80 % increase in acid resistance) at very low concentrations (< 0.08 % by weight of cement). Nanomaterial and cement paste (C-S-H) interactions are shown to be chemical rather than physical, resulting in a denser cement matrix. Graphene oxide (GO) ranks as the best nanoreinforcement candidate due to its low manufacturing cost, ease of use and high modification potential. Key challenges with carbon nanomaterial incorporation are proper dispersion (i.e. due to hydrophobicity) and reduced overall workability (i.e. necessitating superplasticizer use). Specific interactions between C-S-H and GO are unclear, furthermore an absence of proper nomenclature and characterization of GO and graphene has led to ambiguous results. Eventually, this comprehensive review suggests key issues to be explored, such as the translation of positive effects of GO-cement composite on to concrete samples. [Display omitted] •Graphene oxide’s (GO’s) hydrophilicity allows for easy dispersal in the cement matrix.•GO sheets regulate dense microstructural C-S-H growth, accelerating hydration.•CNT impart high tensile strength to cement, their dispersal improved by functionalization.•Incomplete GO characterization has led to missing links in GO-cement research.•Nanomaterials erroneously applied as admixtures with non-optimal combinations.