Non-Invasive Characterisation of Cement-Based Materials by Spectral Induced Polarization
Résumé
In the context of radioactive waste management, concrete is used at various levels of the radioactive waste repositories. For safety purposes, it is of fundamental importance to characterise the mechanical integrity and chemical alteration of cementitious materials. While various sensors have been developed to provide punctual information on concrete infrastructures, indirect non-intrusive methods are still scarce. Spectral induced polarization (SIP) has been considered to fill this gap, based on its sensitivity to both fluid content and specific surface area, the latter being in connection with chemical alterations and pore-fluid interface evolution.
The frequency-dependent polarization of different CEMI and CEMV cement types was investigated for various formulations determined by water/cement ratio and possible aggregate addition. SIP measurements provide complex conductivity values, both at early-age and mature stages.
First results show an increase of both real and complex conductivity components with increasing water/cement ratios, and a decrease but proportional electrical response of mortars (obtained by addition of a resistive sand aggregate) with regard to their corresponding hardened cement pastes. The proportionality coefficient seems independent from the water/cement ratio. The eventual aim is to achieve homogenous quantifiable damaging of the cement-based samples, as to test the observability of its impact on polarization measurements.