Cathodic protection of reinforcing steel

Cable anodes of conducting polymers have an advantage when there are site problems with the installation of other anodes. They are extensively used for the cathodic protection of reinforcing steel in concrete (see Section 19.5.4). 

Cathodic Protection of Reinforcing Steel in Concrete Structures... 

Cathodic protection of reinforcing steel with impressed current is a relatively new protection method. It was used experimentally at the end of the 1950s [21,22] for renovating steel-reinforced concrete structures damaged by corrosion, but not pursued further because of a lack of suitable anode materials so that driving voltages of 15 to 200 V had to be applied. Also, from previous experience [23-26], loss of adhesion between the steel and concrete due to cathodic alkalinity [see Eqs. (2-17) and (2-19)] was feared, which discouraged further technical development. 

The cathodic protection of reinforcing steel and stray current protection measures assume an extended electrical continuity through the reinforcing steel. This is mostly the case with rod-reinforced concrete structures however it should be verified by resistance measurements of the reinforcing network. To accomplish this, measuring cables should be connected to the reinforcing steel after removal of the concrete at different points widely separated from each other. To avoid contact resistances, the steel must be completely cleaned of rust at the contact points. 

Cathodic Protection of Reinforcing Steel in Concrete Structures, Proposed NACE-Standard, Committee T-3K-2 NACE, Houston 1985. 

NACE, Standard RP0290-90, Cathodic protection of reinforcing steel in atmospherically exposed structures , 1990. 

Impressed Current Cathodic Protection of Reinforcing Steel in Atmospherically Exposed Concrete Structures, NACE International Recommended Practice RP02-90-90, NACE International, Houston, Tex., 1990. 

Ebonex / Polymer composite Ti,0, with conductive polymer n.a. n.a. 1000 Cathodic protection of reinforced steel bars in salt-contaminated concrete. Density 2300-2700 kg.m... 

Adequate anode lifetime is obviously also an important factor related to the magnitude and imiformity of current flow. A variety of anode systems have evolved for cathodic protection of reinforcing steel, each with certain advantages and limitations. Continuous surface anodes have been based on conductive bituminous overlays and conductive surface coatings. The former are suited only to horizontal surfaces. In general, good current distribution is achievable with such systems. Discrete anodes have been used without overlays and with cementitious overlays. For horizontal surfaces, anodes without overlays can be recessed in the concrete surface. Nommiform current distribution is a... 

According to British, "Code of Practice for Cathodic Protection" (BS7361 Part 1 1991) and National Association of Corrosion Engineers (NACE) recommended practice "Cathodic Protection of Reinforced Steel in Atmospherically Exposed Concrete Structures" (RP0290-90), typical recommended current densities for protection of atmospherically exposed reinforced concrete structures range between 10 and 20 mA/m of steel.- ... 

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