A Remote Interrogation System for Monitoring Concrete Performance Exposed to Environmental Action

The performance of the surface zone of concrete is acknowledged as a major factor governingthe rate of deterioration of reinforced concrete structures as it provides the only barrier to theingress of water containing dissolved ionic species such as chlorides which, ultimately,initiate corrosion of the reinforcement. In-situ monitoring of cover-zone concrete is critical inattempting to make realistic predictions as to the in-service performance of the structure. Tothis end, this paper presents developments in a remote interrogation system to allowcontinuous, real-time monitoring of the cover-zone concrete from an office setting. Use ismade of a multi-electrode array [19] embedded within cover-zone concrete to acquirediscretized electrical resistivity and temperature measurements, with both parametersmonitored spatially and temporally. On-site, instrumentation, which allows remoteinterrogation of concrete samples placed at a marine exposure site, is detailed, together withdata handling and processing procedures. Site-measurements highlight the influence oftemperature on electrical resistivity and an Arrhenius-based temperature correction protocolis developed using on-site measurements to standardize resistivity data to a referencetemperature; this is an advancement over the use of laboratory-based procedures. The testingmethodology and interrogation system represents an additional technique which could beused for intelligent monitoring of reinforced concrete structures.