Title:
Ultra-Piezoresistive Cement Mortars with CNTs and Fly Ash Admixtures for Structural Health Monitoring
Author(s):
Zhan
Publication:
Web Session
Volume:
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
10/23/2022
Abstract:
The use of fly ash (FA) as cement replacement is one of the most successful strategies to reduce carbon emissions in cement production. However, negative effects caused by the slow pozzolanic reaction of FA make it difficult to take this strategy further. Here we try to use FA as a dispersing agent for carbon nanotubes (CNTs) by in-situ synthesis technique to diminish the negative effects and seek a new application for FA. Upon microwave irradiation, CNTs were successfully synthesized on surfaces of FA particles in 30-40 s. Optical microscopy measurement showed that CNTs on FA dispersed well in water with average 52 µm2 of agglomerated area, about two orders of magnitude lower than the average 1367 µm2 of agglomerated area that the reference CNTs had. The good dispersion of CNTs coated on FA enabled cement mortars to exhibit an ultra-sensitive piezoresistive behavior under compressive loading. The sensitivity to strain of cement mortar containing CNTs coated on FA was 6544 with around 70% of resistivity change within elastic range. This ultra-high sensitivity indicates the huge potential of CNTs coated FA in the fabrication of cement sensor for structural health monitoring, and it opens a new application of FA for the cement industry.