Effect of Undensified Silica Fume on the Dispersion of Carbon Nanotubes Within a Cementitious Composite

The synergistic effect of multi-walled carbon nanotubes (MWCNTs) with different percentages (5%, 10%, 15%) of Undensified Silica Fume (USF) on the mechanical (compressive and direct tensile strengths) and microstructural... [ view full abstract ]

The synergistic effect of multi-walled carbon nanotubes (MWCNTs) with different percentages (5%, 10%, 15%) of Undensified Silica Fume (USF) on the mechanical (compressive and direct tensile strengths) and microstructural properties (through Scanning Electron Microscopy) of cementitious composites has been studied. In the current study, USF was used to enhance the dispersion of nanotubes in the composite due to its small particle size, and to improve the bond between the nanotubes and the cementitious matrix. Ultrasonication techniques were employed to aid the dispersion of MWCNTs in water in the presence of superplasticizer as a dispersion agent. The experimental results indicate that incorporation of USF can considerably improve the dispersion of nanotubes (Fig.1), with subsequent enhancement of composite mechanical performance. This enhancement can be attributed to a reduction in the porosity of the cementitious composites, and improved crack arresting properties. Cementitious composites with hybrid incorporation of MWCNTs (0.025% by cement weight) and 10% USF showed a 36% and 22% increase in compressive strength at 3 and 28 days curing respectively.