Effect of diameter of multi-walled carbon nanotubes on mechanical properties and microstructure of the cement-based materials

Abstract

This paper is intended to investigate the effects of multi-walled carbon nanotubes (MWCNTs) with different inner diameters on the mechanical properties (flexural strength and compressive strength) and microstructures of cement-based materials. Three kinds of multi-walled carbon nanotubes (MWCNTs) with diameter of 10–20 nm, 20–40 nm and 40–60 nm were ready to reinforce cement-based materials. And each batch incorporated 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt% MWCNTs by cement weight. To obtain a uniform distribution of MWCNTs in the cement-based materials, the effects of ultrasonic dispersion time and intensity on the properties of MWCNTs cement-based materials were studied. In addition, the relationships between mechanical properties, porosity and diameter of MWCNTs were investigated. Experimental results showed that the improvements of flexural strength and compressive strength of cement-based materials were altered by increasing the diameter of MWCNTs. Microstructure analysis by SEM and MIP tests indicated that MWCNTs with diameter of 10–20 nm have the best effect on optimizing pore structure. The results of this study were useful to determine the diameter and content of MWCNTs required for optimum pore structure and maximum strength enhancement of cement-based materials.