The mechanical properties of Portland cement mortars blended with carbon nanotubes and nanosilica: A study by experimental design

The pozzolanic effect of nanosilica (NS) particles when combined with Multi Walled Carbon Nanotubes (MWCNT) was studied in Ca(OH) 2 pastes and Portland cement mortars. Experimental design techniques were used to plan the experiments and identify the effect of the nanoparticles on the properties of the cementing matrices by means of Analysis of Variance (ANOVA). Samples were prepared with different combinations of NS and MWCNT. Ca(OH)2 pastes were used to study the effect the nanoparticles had on the Calcium-Silicate-Hydrate (C-S-H) production. Portland cement mortars were used to study the effect of the nanoparticles on the compressive and flexural strength of the cementing matrices. We found that only NS had a significant effect on the C-S-H formation for up to 21 days of hydration, and that MWCNT did not present a positive effect on the mechanical strength of mortars due to the effects of reagglomeration.