Integrated micromechanical model to predict electrical characteristics and piezoresistive sensing performances of CNT doped cementitious composites

Abstract

re-orientation of CNTs and changes in CNT volume fraction, separation distance and percolation threshold. The predicted simulation results are compared with the experimental findings, and both are found to be in close agreement. The fabricated cementitious composites are also tested under compressive loadings to evaluate their piezoresistive sensing performances in both elastic and plastic regions.

The carbon nanotube (CNT)-embedded cementitious composites have gained attention due to their high electrical conductivity. These conductive cementitious composites undergo fractional changes in the electrical resistance (FCR) under the effect of external loadings, thus can be used as piezoresistive strain/stress sensors. In the present study, a micromechanics-based model is developed to predict the lectrical characteristics and piezoresistive sensing performances of the CNT-embedded cementitious composites considering the waviness and agglomeration effects. To simulate the electrical conductivity of CNT-embedded cementitious composites, the Eshelby-Mori-Tanaka approach is adopted. Here, the effective CNT length is modified using a waviness co-efficient and a two-parameter agglomeration model is employed to capture the dispersion state in the proposed model. A series of numerical analysis is performed, and it shows that the proposed model is sensitive to the CNT aspect ratio, interfacial resistivity and dispersion parameters. The experimental value of waviness degree is estimated using image processing tools on SEM micrographs. In addition, the dispersion parameters are optimized using a particle swarm optimization algorithm that follows an adaptive iteration mechanism. The variations in FCR under external loadings are estimated with effects of strain/stress-induced mechanisms