Carbon nanotubes (CNT) and nanofibers (CNF) are among the toughest and stiffest materials discovered to date. Their use in cement composites is not wide spread yet and is of great interest. In this study, some important physical and mechanical properties of microcement mortar with CNT and CNF addition are investigated. Various water cement (w/c) ratios and CNT/CNF dosage rates were explored. The compressive and flexural strengths increased significantly at early ages with CNT/CNF addition However, decrease in strengths was observed for a number of mixes at 28 days age. CNT dosage rate of 0.05% at 0.4 w/c ratio yielded the best combination for mortar strength. Nanoparticles increased flowability, decreased initial setting time and had no effect on bleeding and shrinkage rates. CNT addition resulted in more consistent effects on mortar properties than CNF addition. Additional investigation is needed to fully understand the potential usage of these nanoparticles in cement composites and remove some of the relevant inconsistencies.
