Image Analysis and DC Conductivity Measurement for the Evaluation of Carbon Nanotube Distribution in Cement Matrix

I W Nam,H K Lee

doi:10.1007/s40069-015-0121-8

Abstract

The present work proposes a new image analysis method for the evaluation of the multi-walled carbon nanotube (MWNT) distribution in a cement matrix. In this method, white cement was used instead of ordinary Portland cement with MWNT in an effort to differentiate MWNT from the cement matrix. In addition, MWNT-embedded cement composites were fabricated under different flows of fresh composite mixtures, incorporating a constant MWNT content (0.6 wt%) to verify correlation between the MWNT distribution and flow. The image analysis demonstrated that the MWNT distribution was significantly enhanced in the composites fabricated under a low flow condition, and DC conductivity results revealed the dramatic increase in the conductivity of the composites fabricated under the same condition, which supported the image analysis results. The composites were also prepared under the low flow condition (114 mm < flow < 126 mm), incorporating various MWNT contents. The image analysis of the composites revealed an increase in the planar occupation ratio of MWNT, and DC conductivity results exhibited dramatic increase in the conductivity (percolation phenomena) as the MWNT content increased. The image analysis and DC conductivity results indicated that fabrication of the composites under the low flow condition was an effective way to enhance the MWNT distribution.

Highlights

The electrical and mechanical properties of cement composites with conductive fibers are significantly influenced by the fiber distribution (Sorensen et al 2014; Liu et al 2011; Lee et al 2009)
In determination procedures of volumetric fractions of multi-walled carbon nanotube (MWNT), volume of each constituent material had to be calculated by using true specific gravity of the materials shown in the Sect. 2, volume ratio of MWNT to total volume of the mixture was obtained. 20 % silica fume (SF) was added in the mixtures under the consideration that SF can improve the MWNT distribution (Nam et al 2012)
(2) The DC conductivity of MWNT-embedded cement composites fabricated with different flows was examined and it was observed that the conductivity increased as the flow was decreased

Summary

Introduction

The electrical and mechanical properties of cement composites with conductive fibers are significantly influenced by the fiber distribution (Sorensen et al 2014; Liu et al 2011; Lee et al 2009). The mechanical properties can be improved by the effect of fibers bridging micro-cracks, whereas they deteriorated in the base of a non-uniform distribution of fibers (Sorensen et al 2014; Liu et al 2011). Evaluation of the fiber distribution is important in understanding its influence on the physical properties of the composite materials and making full use of fibers (Liu et al 2011)

Methods

Results

Conclusion