Mechanical and Self-Sensing Properties of Multiwalled Carbon Nanotube-Reinforced ECCs

Chuanbo Liu,Zhiyong Cui,Guozhen Liu,Jian Zhou,Yanhua Guan,Zhi Ge

doi:10.1155/2019/2646012

Abstract

This paper investigates the effect of type and dosage of multiwalled carbon nanotubes (MWCNTs) on the mechanical and self-sensing properties of engineered cementitious composites (ECCs). Two types of MWCNTs (MWCNTa and MWCNTb) were employed. The tensile and flexural strengths of CNT-reinforced ECCs were improved compared with normal ECCs, while the ultimate tensile strain and midspan deflection were reduced. Compared with the dosage of MWCNTs, the type had less effect on these properties. The percolation threshold was around 0.3 wt.%. ECCs containing MWCNTs had good self-sensing ability under different loading conditions. When the midspan deflection increased from 0.1 to 0.6 mm, the fractional change in resistivity reached 9%. The dosage of MWCNTs had a significant effect on the self-sensing ability. As the MWCNT content increased, the amplitude of fractional change in resistivity decreased.

Highlights

Concrete structures deteriorate during their service life because of continuous use, environment, difficulties in proper inspection methods, lack of maintenance, etc.erefore, structural health monitoring (SHM) is critical because of the huge loss of life and property caused by structural failure
E self-sensing ability of multiwalled carbon nanotubes (MWCNTs)-reinforced engineered cementitious composites (ECCs) was investigated under three loading scenarios: (1) continuous flexural loading: the specimen was continuously loaded at a constant rate of 0.5 mm/min until failure; (2) multiple-stage loading: the specimen was loaded at five stages
More cracks developed, resulting in the plastic strain at increasing stress. e effect of MWCNTs on the first cracking strength, first cracking strain or deflection, ultimate strength, and ultimate strain or deflection was discussed

Summary

Introduction

Concrete structures deteriorate during their service life because of continuous use, environment, difficulties in proper inspection methods, lack of maintenance, etc. Most studies focus on type and dosage of additives, mixing method, and selfsensing ability of materials or structures [1,2,3,4,5,6,7,8,9,10]. Al-Dahawi et al [10] investigated the effect of different dispersion methods on the electrical resistivity and found that mechanical mixing with shear effect was very influential in dispersing CNTs. Currently, most studies used cement. Few research was conducted to investigate the influence of types of CNTs on the mechanical and self-sensing properties of CNT-reinforced ECCs at different midspan deflection ranges.

Cement Fly ash

Normal ECC mix proportions

Results and Discussion

CNTa CNTb