Effect of titanate nanotubes on the properties of cement-based composites

Abstract

Recently, nano-reinforcing technology using nanotubes has attracted significant attention as a method of compensating for poor tensile strength and improving the performance of various cementitious materials. In this study, for the first time, we investigated the mechanical properties, microstructure, and early hydration kinetics of cement paste with titanate nanotubes (TNTs). The microstructures of the fracture surfaces of samples were investigated with scanning electron microscopy (SEM). TNTs were successfully synthesized using a hydrothermal method. With 0.5 wt.% addition of TNTs, both compressive and flexural tensile strength were improved for all curing days, but it was found that TNT reinforcement was more effective for flexural strength enhancement. Moreover, the analysis of the hydration kinetics by isothermal conduction calorimetry clearly showed that the TNTs improved the hydration kinetics of the pure cement clinker phase (C3S) at the initial stage of hydration. Pore analysis showed that nano-sized TNTs filled pores between 10 to 100 nm in size, resulting in a denser microstructure of the cement paste. SEM images clearly showed that TNTs bridged cracks and voids in the cement paste, which mitigated and altered crack propagation in the cement paste. These results suggest that TNTs have great potential as a new nano-reinforcing agent for cementitious materials.