Dynamic and physio-mechanical effects of combined functionalised MWCNTs and nanosilica particles on cement composites

Abstract

The aim of this work was to study the single and combined effects of laboratory synthesised, purified, functionalised multi-walled carbon nanotubes (MWCNTs) and nanosilica (NS) particles on the physico-mechanical and dynamic properties of cement mortars. Portland cement was partially substituted by nanostructured MWCNTs (0.2, 0.4, 0.6, 0.8 and 1.0 wt%), then NS (2, 4, 6, 8 and 10 wt%) and finally both MWCNTs and NS in different ratios. The physico-mechanical and dynamic properties of the composite materials (compressive strength, bending strength, water consumption and initial and final setting times) were measured. The morphology of hardened samples was studied by scanning electron microscopy (SEM) and transmission electron microscopy was conducted to determine the size of the nanoparticles. The results showed that, compared with control samples, the compressive strength of the cement mortars containing MWCNTs increased by 27% at 28 days and the bending strength increased by 9.9% at early age. SEM images showed that the cement mortar containing 0.4 wt% MWCNTs had a more compact microstructure than then the control samples due to the bridging effect of the MWCNTs.