Ultra high performance cement-based composites incorporating low dosage of plasma synthesized carbon nanotubes

Ultra high performance cement-based composites (UHPCs) have gathered more attention and interest due to their excellent properties. In this study, a new type of carbon nanotubes (p-CNTs) synthesized by plasma process was used to modify the mechanical properties of UHPC at low dosage. The dispersion and sedimentation of p-CNTs were investigated and the mechanical properties of the resulting CNT modified UHPCs (CNT-UHPCs) were studied. The results showed that p-CNTs can be dispersed uniformly in water through ultrasonication without the need of surfactant or chemical modification on surface. In addition, the p-CNTs showed a much improved dispersion and stability as compared to the normal CVD synthesized CNTs. Well-dispersed p-CNTs greatly enhanced the flexural strength of UHPC from 12.5 to 21.2 MPa at a dosage of only 0.067% by the weight of cement. This highlighted the importance of dispersion of CNTs which not only improved the bridging efficiency but also reduced the CNT dosage and cost. All of these make the applications of nano-material feasible and more economical attractive.