Impressed Current Cathodic Protection

Steel reinforced concrete is one of the most durable and reliable construction materials which can suffer in high chloride environments from corrosion due to chloride induced break down of the normal passive layer protection. In order to increase the service life of the structure we go for substance that resist corrosion and can also enhance easy re-habilitation work in the future. The main objective of our project is to examine the change in diameter of the Turbo Mechanically Treated (TMT) bars and to isolate the chlorine content in concrete after inducing corrosion. Thereby, recommending the best corrosion resistor that can be used practically in the field to resist corrosion. This paper reports the investigation carried out to study the effects and comparison of corrosion with protection on steel and concrete of reinforced concrete beam. To carry out the examination, six specimens of size 100mm x 100mm x 500mm were used. The first specimen is a normal beam which is used as a benchmark to evaluate the performance of the other five beams. The second beam is a chlorine contaminated beam of which the effect of highly concentrated chlorine water in corrosion is studied. In the other four beams, different materials such as corrosion inhibitors, fusion bonded epoxy coating, Galvanic Anode and Zinc rich epoxy primer were used and their performance to resist corrosion were evaluated. Corrosion was induced in the beam by electro-chemical process as per American Society for Testing and Materials (ASTM) standards and period changes in the rod were analyzed by using half-cell potential. After suitable period of inducing corrosion various physical and chemical tests were carried out to study the resistance offered by these various materials.

IEEE, 2019

Corrosion is a universal process occurring due to chemical reactions between metal and the environment. Corrosion of the metal can be controlled by numerous methods, and among many controlling methods cathodic protection is noteworthy. Cathodic protection of metal consists of two methods namely impressed current method and sacrificial anode method. Both methods deal with the transportation of electrons either receiving or donating from or to the metal or to the environment. Again, the electric resistance of a metal piece is inversely proportional to this cross-sectional area. If a metal bar corrodes fast, then its crosssectional area reduces rapidly and its electric resistance increases highly. So, the relation between corrosion and electrical resistance of the metal is a helpful parameter to determine the corrosion rate. In this paper, we determine the corrosion behavior of mild steel exposed to different concentrations of ionic liquid to compare the possible variations in the corrosion protection techniques for the mild steel used.

Indian Journal of Science and Technology, 2017

Cathodic Protection to the embedded steel in concrete was established using sacrificial pure magnesium anode to prevent the corrosion of reinforcement. Two slabs were casted one containing 3.5% sodium chloride with respect to weight of cement and the other without NaCl. Both the slabs were provided with cathodic protection of pure Magnesium anode. Half cell potential measurements with Standard Calomel Electrode as reference electrode were taken at regular intervals and for a number of days. It could be observed that the potential of the slab decreased with increase in distance from the anode and reduced with time. Thus, magnesium anode was found to shift the potential of steel to more negative potential initially and later towards less negative potentials with respect to time. It could be concluded that use of Magnesium anode could prove to be an effective means of corrosion prevention.

The paper stresses corrosion risks from huge underground engineering steel structures within the metropolitan area of Kaduna-a top city in Nigeria. Cathodic protection (CP) is examined as an effective, economical and durable method of preventing corrosion of such structures if suitably designed-installed. Variables that can cause wide differences and difficulties in CP designs such as material make, surface area and nature of structure, corrosivity level of environment, etc, are recognized. Some supplementary information that accounts for complexity of such variables which can be used to optimize CP design of the structures was sought experimentally. Relative performances by zinc, pure magnesium and magnesium alloy as common and cheap galvanic anodes were investigated in a laboratory CP of polished bare low carbon steel specimens in soil of surveyed resistivity spectrum 31.9-152.9 ohm-m from the area. Specimens were exposed with and without CP by the anodes at ambient temperature up to 40 days in various samples of the soil. Levels of specimen protections were determined by analysis of obtained information on their corrosion rates and polarized potentials relative to the unprotected ones at 8-day intervals. The analysis indicated that; corrosion of the structures can be optimally reduced to negligible rates by polarizing them to-0.85V versus Cu/CuSO 4 electrode with the anodes, pure magnesium is comparatively the best of the anodes for CP of the structures in terms of economy and effectiveness followed by magnesium alloy, and a unit surface area of the anodes can protect up to nearly 1200 units of the structure with the-0.85V protective potential depending on the anode type.

Chemical Data Collections

The performance of two different sizes of galvanic magnesium anodes on the cathodic protection of mild steel in 0.5 M hydrochloric acid was evaluated at room and elevated temperatures. The cathodic protection reactions process was observed by weight-loss method's corrosion rate calculation and potential and current measurement methods. The magnesium anodes were observed to be effective as sacrificial anode in the tested environments. The results obtained for the potential and current measurements bear close correlation with the corrosion rate method in the hydrochloric acid environment. The varying anode cross-sectional areas used showed the anode size effects. The varied percentage protection of magnesium anodes ranged between 5.88 and 59.81% (Mg 1); and, 16.80 and 48.65% (Mg 2) respectively at 27 °C. At 60 °C, the percent change ranged between 22.49 and 61.46 (Mg 1); and 21.7 and 68.95 for Mg anode 2.