Effects of electrodes location in a three-electrode system on polarization measurements of reinforcing steel in concrete cores drilled from a structure
Katedra Konstrukcji Budowlanych, Politechnika Śląska
This article describes results from d.c. polarization measurements of rebar fragments in concrete cores drilled from a structure. In the first stage of tests, a traditional arrangement of three electrodes was applied, in which the working electrode was the rebar in a cylindrical core, the counter electrode was a stainless steel disk, and the reference electrode was a traditional Ag, AgCl | Clˉ electrode in a glass body. The counter and reference electrodes were applied to a flat surface of the specimen covered with a wet felt washer or conductive gel. In the second stage of tests, an alternative electrode setup was used, in which the reference electrode was covered with the varnish and silver powder additive present on the specimen side surface, and a graphite rod in the specimen was used as the reference electrode. Results from tests performed under dry air conditions indicated that traditional electrodes applied to concrete surface caused significant discrepancies in results, and consequently their analysis became impossible. And electrodes permanently embedded into concrete provided satisfactory results for tests under the same conditions.
Keywords: RC-structures, concrete, reinforcing steel, corrosion of reinforcement, diagnosis, polarization measurements, LPR measurements
2019, Vol. 62, nr 8, pp.252-258
Galvanic anode cathodic protection of marine structures – design according to DNVGL-RP-B401 standard
SPZP CORRPOL, Gdańsk
Despite it’s imperfections, corrosion protection using zinc and aluminum – metals, with electrochemical potential more electronegative than steel – is still widely utilized in marine industry. It’s popularity comes from it’s simplicity and high resistance to damages. The proper choice of anticorrosion system impacts the lifetime of an object and determines it’s renovation intervals. Cathodic protection in marine industry can be achieved either by coating the steel surface with zinc – or aluminum – film or by connecting sacrificial anodes, made of zinc or aluminum alloys, do the structure. The paper describes recommendations and guidelines for designing cathodic protection systems that utilize sacrificial anodes and works along with the system of protective coatings. Cathodic protection designed in accordance with described recommendations is based on the mathematical model of electrochemical system steel structure – sacrificial anodes – electrolytic environment. The model considers many aspects, which are usually being omitted by local designers in their conventional cathodic protection designs. The DNVGL-RP-B401 standard was developed by Norwegian classification society Det Norske Veritas. Recommendations and guidelines for cathodic protection systems described in the standard are accepted and applied by designers worldwide
Keywords: cathodic protection in marine industry, galvanic anode cathodic protection, galvanic anode protection system design
2019, Vol. 62, nr 8, pp.259-264
CORROSION PROTECTION IN PRACTICE
KT Index – Cathodic protection effectiveness evaluation in Italy
End Corr, Włocławek
One of the biggest innovation in the 21st century cathodic protection technology is a remote monitoring. This solution enables an easy and precise control over cathodic protection systems. It is possible to analyze evolution of an electric potential simultaneously in a number of different locations. Most of the market available remote dataloggers perform measurements with a 1 Hz sampling. All-day measurements in a number of places results in a giant number of data to be processed. To take full advantage of the remote monitoring it is necessary to use a high end data analyzing software. An algorithm that calculates a global evaluation of the effectiveness of the whole cathodic protection system is a very helpful tool. This tool makes it easy to understand a current condition of the CP system without inspecting all single measurements done by all dataloggers. In Italy all gas transmission and distribution companies has to submit such evaluation to the technical supervision authority. This evaluation is called KT Index. This paper describes basic concepts of the KT Index. An algorithm of the KT Index calculation is included.
2019, Vol. 62, nr 8, 265-268
Certification of persons involved in cathodic protection – an international standard
SPZP CORRPOL, Gdańsk
Cathodic protection technology of metallic objects in electrolytic environments requires specialist theoretical and practical knowledge of people who implement it in practice. The development of cathodic protection technology, progress in standardization and certification as well as a new international standard which specifies the required competences of persons dealing with this corrosion protection technique are presented.
2019, Vol. 62, nr 8, pp. 269-273