The critical incorporation concentration (CIC) of dispersed carbon nanotubes for tailoring multifunctional properties of ultra-high performance concrete (UHPC)

Abstract

This study aims to elucidate the effect of carbon nanotube (CNT) concentrations on the mechanical, electrical, shrinkage, and thermal properties of ultra-high performance concrete (UHPC). The stable dispersion of CNTs was achieved using well-dispersed CNT suspension and confirmed by consistent decrease in electrical resistivity. The autogenous shrinkage was effectively reduced by over 30% by incorporating around 0.5 wt% CNT content. While thermal conductivity was gradually increased with increasing CNT dosage, the volumetric heat capacity was minimized, and the thermal diffusivity was maximized at the percolation threshold. The addition of CNTs positively affects engineering properties; however, above 0.5 wt% CNT content, compressive strength, elastic modulus, and thermal diffusivity were deteriorated mainly due to higher porosity from reduced fluidity. From these results, the single value of the critical incorporation concentration of CNTs could be proposed as 0.5 wt% for tailoring the multifunctional properties of CNT/UHPC composites.