Abstract:
Multi-walled carbon nanotubes (MWCNTs) belongs to the most promising family of nano-materials that have the potential of effectively altering the characteristics of com-posite matrices. But, their effectiveness strongly depends upon the level of dispersion of these nano-metric sized structures in the composite matrices. In cementitious envi-ronment, achieving efficient dispersion of MWCNTs have remained a long standing issue and in the current research work, the formulation of efficient dispersion scheme for the dispersal of MWCNTs in the cement mortar matrix using natural Acacia Nilotica Gum and commercial Triton X-100 has been focused. Further, the influence of efficient dispersion of MWCNTs on the hydration kinetics, early-age volume stability, fracture properties and the microstructure have been studied in detail. In total, five formulations containing 0.0, 0.025, 0.05, 0.08 and 0.10 MWCNTs by weight percent of cement were prepared and analyzed in detail. It was observed that the natural surfactant produced efficient dispersion at much reduced cost (>14% approx.) compared with the commer-cial alternate. The estimated weight efficiency factor ‘ᶲ’of Acacia Nilotica Gum was found 6.5 times higher than Triton X-100 as dispersant resulting in remarkable increase of 23% in modulus of rupture on 0.08 wt.% addition of MWCNTs. Besides, strength enhancement the dispersed MWCNTs also improved the first crack and ultimate frac-ture toughness by 51.5% and 35.9%, respectively. The field emission scanning electron microscopy of the cryofractured samples revealed efficient dispersion of MWCNTs in the matrix leading to the phenomenon of effective crack bridging and crack branching in the composite matrix. Furthermore, significant reduction in total volumetric shrink-age was also observed in the MWCNTs reinforced composites with Acacia Nilotica Gum used as dispersant.
