Monitoring of drying and imbibition of concrete using embedded resistivity sensors for the estimation of permeability

Abstract

Assessing the permeability of concrete is crucial as it governs the transport of aggressive agents, such as chlorides and carbon dioxide, which are key factors in the degradation mechanisms. Moreover, concrete's permeability constitutes an essential input parameter for durability models. Concrete's permeability can be measured directly (by experimental methods) or indirectly by fitting a transport model to saturation degree profiles. In this paper, we introduce a novel indirect method for estimating the permeability by monitoring the saturation degree profiles with embedded resistivity sensors. These embedded resistivity sensors are used for the evaluation of the saturation degree profiles over time during two experiments: drying and imbibition with tap water. Firstly, measured resistivity profiles are converted to saturation degree profiles, using a calibration curve established on concrete cores of the same formulation. Concrete's permeability is then estimated by fitting a hydric transport model to the experimental saturation degree profiles. Permeability values estimated using the embedded sensor are compared to those obtained by two reference methods: assessing the mass loss of a non-monitored specimen subjected to drying and saturation degree profiles obtained by gammadensimetry measurements. The permeability values obtained with the monitoring method are consistent for drying and imbibition experiments and fall within the range of values found in the literature. This is very promising for the continuous monitoring of concrete by embedded resistivity sensors.