Mechanical Characterization of Nano-Reinforced Mortar: X-ray Micro-CT for 3D Imaging of Microstructure

Microstructural characteristics and mechanical properties of nano-reinforced cementitious mortar using multi-walled carbon nanotubes (MWCNTs), dispersed in an aqueous solution by applying ultra-solicitation, were studied using X-ray microcomputed tomography (micro-CT), an innovative, non-destructive technique. This useful method was applied for characterizing the cementitious composites’ spatial micro-pore structure. The changes due to the MWCNTs’ integration into the mortar matrix and their effects were studied. The analysis revealed that the density and porosity values processed by micro-CT imaging are crucial parameters. They correlated with the mechanical strength of 2 × 2 × 8 prisms (in cm) in order to evaluate the dispersion effect of the different nanotube concentrations, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, and 0.5 wt.% by the mass of cement. The results highlight the linear correlation of the density, porosity, and spatial pores’ distribution obtained by the micro-CT 3D in vivo imaging of the microstructure, with the nanotubes’ concentration and flexural and compressive strengths. This investigation was achieved by proving that a deeper understanding of the complex nano- and microstructures can be utilized for the design of advanced cementitious composites at multiple scales.