Piezoresistive geopolymer enabled by crack-surface coating

The conductive polymer was introduced to crack surfaces in geopolymers to enable piezo-resistivity. In combination with crack morphology characterization and the piezo-resistive test, the functionalized geopolymer was found to achieve a high sensitivity (with Delta R/R-0/Delta epsilon equals to 376.9 for loading and 513.3 for unloading) to both small external stress (less than 2 MPa) and wide range of strains (up to 1700 mu epsilon). This piezo-resistive behavior can be well described by a coupled mechanical-conductive contact mechanism. A new way to enable the self-sensing function of materials utilizing their existing micro-features was successfully proposed and validated. (C) 2019 Elsevier B.V. All rights reserved.