Size-dependent regulation of graphene nanoribbons on cement hydration and mechanical properties

초록

Graphene nanoribbons (GNRs) have attracted increasing attention for reinforcing cement-based composites; however, their size-dependent effects and underlying mechanisms remain insufficiently understood. While carbon-based nanomaterials are known to accelerate hydration and enhance strength, the combined influence of structural transformation, specific surface area (SSA), and dispersion characteristics has not been systematically clarified. This study investigates the size effect of GNRs synthesized from multi-walled carbon nanotubes (MWCNTs) with different diameters on dispersion behavior, hydration kinetics, and mechanical properties of cement paste. Results show that the unzipping process markedly increases SSA, whereas smaller GNRs exhibit higher SSA but reduced dispersion quality. Among all samples, medium-sized GNRs (GNRs-M) achieve an optimal balance between SSA and dispersion, leading to the greatest mechanical enhancement, with compressive and splitting tensile strengths increasing by 40.71% and 25.59% at 28 days, respectively. Calorimetry and phase analyses confirm that GNRs-M most effectively regulate hydration and promote hydration product formation, resulting in a denser microstructure. The findings reveal that performance improvement depends on the synergistic balance between morphology and dispersion rather than SSA alone, providing new guidance for the rational design of carbon nanomaterial-reinforced cement composites.

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