Acid-treated carbon nanotubes and their effects on mortar strength

In the present study, multi-walled carbon nanotubes (MWCNTs) were treated in an acidic mixture solution, made with nitric and sulfuric acids in a ratio of 3:1 by volume. The durations of the treatment were 100 and 180 min. The defects of these treated MWCNTs were examined using Raman spectroscopy. The attachment of hydroxyl functional groups to the walls of the MWCNTs were verified using FTIR spectroscopy. The dispersion of CNTs with acid treatment is assessed using UV-Vis spectroscopy and Scanning Electron Microscopy (SEM). The results indicate that the duration of the acid treatment has significant effect on both the degree of defects and functionality of the MWCNT. The compressive strength of mortar increased with the addition of the acid-treated MWCNTs; however, no appreciable difference was noted for the two treatment durations under this study.