Galvanized reinforcement, concrete

FIGURE 1. Bacterial density of biofilms developed on main pipe lines from carbon steel (1,2) or reinforced concrete (3,4) and concrete tank (5,6) in drinking water distribution system Yovkovtsy , domestic installation from galvanized steel (7,8) and test surfaces from stainless (9) or carbon steel (10). 

P. Pedeferri, Stray Current Induced Corrosion in Reinforced Concrete Structures Resistance of Rebars in Carbon, galvanized and Stainless Steels (in Italian), La Metallurgia (10 ... 

Galvanized-steel rebars can be used as a preventative measure to control corrosion in reinforced concrete structures exposed to carbonation or mild contamination with chlorides, such as chimneys, bridge substructures, tunnels and coastal buildings. 

Galvanized reinforcement offers significant advantages compared to carbon steel under equivalent circumstances. These include an increase of initiation time of corrosion a greater tolerance for low cover, e. g. in slender (architectural) elements, and corrosion protection is offered to the reinforcement prior to it being embedded in concrete. 

L. Bertolini, M. Gastaldi, T. Pastore, MP. Pedeferri, P. Pedeferri, Effects of galvanic coupling between carbon steel and stainless-sted reinforcement in concrete , Int. Conf. on Corrosion and Rehabilitation of Reinforced Concrete Structures, Federal Highway Administration, Orlando, 7-11 December 1998 (CD-ROM). 

E. Maahn, B. Seirensen, The influence of microstructure on the corrosion properties of hot-dip galvanized reinforcement in concrete , Corrosion, 1986, 42, 187-196. 

All of the correlations seen above refer to situations of steel reinforcement in the free corrosion condition, that is, in the absence of factors that modify the potential of the system. They are in particular not appHcable to structures in concrete containing corrosion inhibitors galvanized reinforcement (on stainless steel it is possible in the same way) structures subjected to electrical fields produced by stray current that induce current exchange between reinforcement and concrete (this case is dealt with in Section 9.4). 

L. Maldonado, Chloride threshold for corrosion of galvanized reinforcement in concrete exposed in the Mexican Caribbean, Mater. Corros. 60 (2009) 536—539. 

F. Tittarelh, G. Moriconi, Comparison between surfece and bulk hydrophobic treatment against corrosion of galvanized reinforcing steel in concrete, Cem. Concr. Res. 41 (2011) 609-614. 

As discussed earlier, there are two forms of cathodic protection, impressed current and galvanic. The impressed current system has been described earlier and is the system with the longest history of application to atmospherically exposed reinforced concrete structures. An alternative method... 

The earliest galvanic systems for reinforced concrete were installed in the United States on bridge decks. The first was in 1978 using aluminium, and from 1976 to 1980 a study was carried out on a zinc system in Illinois. 

The electrolyte is the medium through which the ionic current flows from the anode to the cathode. It can be soil or sea water for pipelines or ships. In the case of atmospherically exposed reinforced concrete structures it is the concrete pore water. In the case of buried or submerged concrete it will be firstly water or soil and then the concrete pore water as shown in Figure 7.4 for a galvanic system. Our discussion will concentrate on atmospherically exposed concrete structures. 

ILZRO(1988). Galfan Manual, 3rded. ILZRO, Research Triangle Park, NC, 139 pp. ILZRO (1981). Galvanized Reinforcement for Concrete—II. ILZRO, Research Triangle Park, NC, 208 pp. and appendices (includes bibliography of 394 refs). 

Martin, H., and Rauen, A. (1975). Studies on the Behavior of Galvanized Reinforcing Steel in Concrete. Gemeinschaftsausschuss Verzinken eV, Diisseldorf, Report 68, pp. 61-77 (in German). 

Porter, F. C. (1985). Galvanized reinforcement for concrete. 1st Int. Conf. Deterioration and Repair of Reinforced Concrete in the Arabian Gulf. Construction Industry Research and Information Association (U.K.), pp. 193-201. 

Since the towers are with reinforced concrete structure, in which the ordinary steel bars can be used as natural down leads. In addition, two-50 5 hot galvanized flat steels should be set as the special down-conductors. 

Clear, K. C., "Time-to-Corrosion of Reinforced Steel in Concrete Slabs, Vol. 4—Galvanized Reinforcing Steel, Interim Report, December 1981, Federal Highway Administration Report No. FHWA/RD-82/028, FHA, U.S. Department of Transportation, Washington, DC. 

Electrochemical protection is divided into cathodic and anodic protection. Cathodic protection based on the change of potential of a metal in the negative direction is realized in electrolytic environments, in most cases neutral, mainly of steel and reinforced concrete structures. A well-designed and correctly realized CP reduces the corrosion rate to almost zero. In practice it is realized with the use of an impressed current or protectors (galvanic anodes). The scope of application is enormous and continuously increases. With the use of this technology it is possible to protect vessels and ships, docks, berths, pipelines, deep wells, tanks, chemical apparatus, underground and underwater municipal and industrial infrastructure, reinforced concrete... 

Galvanized reinforcement, i.e. zinc coatings formed by dipping clean rebars in a bath of molten zinc, can protect steel in concrete from corrosion attack. However, the performance reported in the literature is contradictory (Bentur et al., 1997). Galvanized rebars remain passive in carbonated concrete and the corrosion rate is much lower than with black steel. In situations where chloride induced corrosion prevails, a delay in the initiation of corrosion can be expected, but at high chloride concentrations depassivation cannot be avoided completely. 

Arnold, C. J., "Galvanized Steel Reinforced Concrete Bridge Decks Progress Report," Report No. FHWA-MI-78-R1033, Washington, D.C., Federal Highway Administration, 1976. 

Common uses of the impressed current method of protection include long transmission pipelines, complex underground structures, marine structures, ship hulls, and replacement for dissipated galvanic systems, large condenser water boxes, reinforcing steel in concrete, bare or poorly coated structures, unisolated structures and water storage tank interiors. 

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