Synergistic effect of carbon nanotube/TiO2 nanotube multi-scale reinforcement on the mechanical properties and hydration process of portland cement paste

Abstract

The synergistic effect of hybrid carbon nanotube (CNT)/TiO2 nanotube (TNT) multi-scale reinforcement on the mechanical properties, early-age hydration process, and microstructure of Portland cement paste was investigated. In this study, TNT was synthesized via the hydrothermal process. The dispersion of CNT in an aqueous solution was enhanced in the hybrid CNT/TNT. Further, the dispersion state of CNT was modified to a smaller agglomeration of hybrid CNT/TNT. At the optimal CNT/TNT ratio (0.1 wt% CNT/0.5 wt% TNT), an earlier initiation of the acceleration period in the hydration process, an enhanced degree of hydration, and improvements of 29% and 40% in the compressive and splitting tensile strengths of the cement paste, respectively, were observed. Further, the time taken for the occurrence of the calorimetric peak of cement paste was shortened from 3 h (without nanotubes) to 2.3 h and the time taken to achieve maximum peak intensity was shortened from 13.6 h to 11.5 h. Enhancing effect of the hybrid CNT/TNT on the hydration and mechanical properties of cement paste was more apparent than only that of CNT or TNT. The results suggest that using multi-scale hybrid CNT/TNT can be feasible as a new nano-reinforcing method for various cementitious materials.