Effect of multi-wall carbon nanotubes on the flexural performance of cement based composites

Abstract

In this work, multi-wall carbon nanotubes (MWCNT) are added (0-0.5 wt%) into a cement matrix to improve the flexural performance of the resulting nanocomposites. Under static testing, the compressive and flexural strengths were found to increase with MWCNT content with an optimum content of 0.2% and 0.1%, respectively, before decreasing because of dispersion problems (agglomeration). But it was observed that increasing the mixing time and adding silica fume improved the MWCNT dispersion. Under fatigue testing, similar trends were obtained with respect to MWCNT content as the maximum fatigue life was observed at 0.2%. A comparison between nano-silica and MWCNT reinforced concrete is also made showing that MWCNT provides better improvement at lower content. The MWCNT reinforced cement-based composite results were well fitted using linear regressions. Finally, a morphological analysis via scanning electron microscopy (SEM) was performed to explain the results based on the micro-mechanical mechanism of MWCNT reinforced composites.