A suggestion for a two-stage corrosion mitigation system for steel reinforced concrete structures

Cathodic protection (CP) of steel reinforced concrete is a well-established technique for controlling reinforcement corrosion of structural elements. Long-term maintenance of the system, however, is seen as a burden to most structure owners and managers as it involves additional and continual costs. There is, therefore, a requirement for simpler CP systems to be made available which will involve less maintenance and monitoring requirements. This paper demonstrates a methodology, backed by laboratory experiments, that has enabled such a user-friendly system to be developed and applied.

The paper presents results that demonstrate corrosion arrest of steel samples, corroded by embedding in a range of chloride-containing mortars and delay in the onset of corrosion in chloride-free mortars subsequently exposed to external chlorides. This process is suggested as Stage-1 of a two-stage process for long-term protection of steel reinforcement, Stage-2 being corrosion or cathodic prevention, after corrosion arrest has been demonstrated, for which galvanic anodes have been proven to adequately achieve. The key element of the two-stage process is to establish that corrosion arrest has been attained. The paper suggests, with examples, monitoring of the depolarisation and depolarised potentials and use of the Butler Volmer equation for the estimation of the steel corrosion rate as possible validation techniques that can be simply achieved with minimal monitoring throughout the service life of the structure.