Surface Modification of Carbon Nanotubes Using Carboxymethyl Cellulose for Enhanced Stress Sensing in Smart Cementitious Composites

Abstract

Carbon nanotubes (CNTs) when used as additives in cementitious materials are known to enable the piezo-responses making them smart materials. The piezo-responses can potentially be used to monitor the applied forces, stress, and the resulting performances of the associated materials. An effective and reproducible method for smart cementitious material production needs to ensure uniform dispersion of CNTs within the cementitious base, and that should lead to better sensitivity and consistency in sensing by the smart cementitious materials. This paper presents a surface modification method of CNTs using carboxymethyl cellulose (CMC) to improve the performance of the CNT-modified smart cementitious materials for stress sensing. Compared to the two commonly used CNTs dispersion methods, the direct mixing and the surfactant surface treatment methods of dispersing CNTs, the new CMC surface modification method developed within this study significantly increased the stress detection sensitivity and consistency, and reduced the measurement hysteresis.