Corrosion of steel bars can adversely affect the durability of concrete structures. Galvanic Cathodic Protection (GCP; zinc anodes connected to steel bars) can arrest ongoing corrosion and extend the ‘major repair-free service life’ of structures by about 20-25 years. However, the use of poor quality anodes and/or design/installation practices leads to inadequate corrosion control and eventually negative perceptions of GCP technology. Hence, there is a need to develop a non destructive test (NDT) method to assess the quality/performance of anodes embedded at any location within the structure; that too at any time during/after installation. Typical approaches rely on testing electrical current from a very small number of pre defined anodes (say, one in about 2000 anodes) and are inadequate. This thesis focuses on generating electrochemical database and models towards developing an NDT method for quality control of GCP systems. First objective was to assess the effectiveness of the existing criteria to assess the performance of anodes in highly resistive concrete. For this, electrochemical responses were collected repeatedly (for about 2 to 4 years) from about 150 anodes (laboratory/field studies). This data revealed the inadequacy of existing criteria. Hence, a new method (based on potential gradient mapping) was developed to assess the performance of a few predefined anodes in structures. Second objective was to develop database and NDT method for assessing the entire GCP systems in concrete structures. For this, GCP systems were modeled as an electrical/electrochemical system using Laplace and Butler–Volmer equations and finite element analysis. The input parameters were quantified from potentiodynamic polarization tests on 20 steel and 15 zinc pieces in cement mortar (instead of metal-solution systems – to be more realistic). Third objective was to find a suitable parameter to enable the use of the NDT method in the field. For this, electrochemical impedance spectra (EIS) from 15 concrete prisms with embedded steel and anode were collected and analysed. Then, based on an equivalent circuit model, the shift in phase-angle was found to be a suitable parameter to assess the performance of embedded GCP systems. Overall, this thesis provides scientific models and database towards developing NDT methods to assess the performance of GCP systems, at any time during/after installation.
12 febbraio 2026
Martedì, 12 febraio 2026, 12:30
Dipartimento di Ingegneria Strutturale e Geotecnica,
Sede di Ingegneria,
Via Eudossiana 18,
Edificio A, Terzo piano, Area Strutture,
Sala Riunioni 329