Analysis of Cementitious Composites Prepared with Carbon Nanotubes and Nanofibers Synthesized Directly on Clinker and Silica Fume.

Cement pastes and mortars were prepared incorporating carbon nanotubes (CNTs) and nanofibers (CNFs) synthesized directly on ground clinker and silica fume. Setting times of the cement pastes were not significantly influenced by the presence of nanotubes and nanofibers. Mortar mechanical behavior (compressive and flexural tensile strength) was evaluated and compared with reference mortars having the same composition but without nanotubes and nanofibers. The mortars incorporating nanostructured clinker showed 5.4–14.1% higher compressive and flexural tensile strengths, respectively. The same values for the mortars prepared with nanostructured silica fume were 39.6 and 9.4%, respectively. Gas adsorption porosimetry and helium pycnometer analysis showed modification of the pore structure as an effect of nanostructured material addition: pore diameter decreased, specific surface area increased, yet density of the mortars remained unchanged. [ABSTRACT FROM AUTHOR]