Resistivity and Capacitance-Based Strain Sensing of CNT and GNP Reinforced Concrete

Abstract

The accurate stress and strain sensing in concrete is critical for reliable monitoring of its mechanical condition and cracking/failure detection. This work presents results of an experimental study of resistivity and capacitance-based sensing of conducting nanoengineered concrete at all stages of deformation up to failure. While the change in resistivity is widely regarded as the preferred indicator for evaluating the sensing ability of a nanocomposite material, we have shown that piezoresistivity depends on dispersion/exfoliation. Results of the fractional change in resistivity of concrete reinforced with well dispersed/exfoliated carbon and graphene-based nanomaterials, such as carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) showed a piezoresistive signal of 160% at all stress strain levels up to failure. Nanocomposites with as received CNTs and GNPs did not exhibit any change in resistivity during the loading-unloading cycles. The fractional change in capacitance however was adequate for recognizing the change in the applied stress; thus, successfully enabling continuous strain sensing.