The effect of moisture and reinforcement on the self-sensing properties of hybrid-fiber-reinforced concrete

Abstract

This study presents the piezoresistive properties of a hybrid fiber-reinforced concrete (HyFRC) for structural healthmonitoring.ThisHyFRCmixture incorporatesmicroPVAandmacro steel fibers to control the crack propagation. Investigations on self-sensing concrete (SSC) focusmainly onmixtures containing highly conductive fillers such as carbon nanotubes, graphite or nickel powder which results in a highly engineered cost-intensivemix composition for structural applications.This paper investigates the sensing ability of a cost-effective structural concretemixture by considering the environmental conditions of engineering structures e.g. themoisture content aswell as the influence of reinforcement on the electrical resistancemeasurement.The sensing parameterswere evaluated by performing simultaneously bending tests and Electrochemical Impedance Spectroscopy (EIS) on beamswith and without steel reinforcement. Furthermore, the influence of the pore solution on the EIS was investigated on specimenswith varyingmoisture contents.The sensing behaviorwas compared to a controlmixture without steel and PVAfibers.Results showed a significant lower initial resistivity for theHyFRCmixture compared to the ordinary concrete aswell as the activation of the self-sensing properties due to the incorporated steel fibers. Finally, the influence of the pore solution on the EISmeasurement is addressed and emphasizes the imperative need to consider themoisture content of self-sensingmaterials.