Rebars coating

EPON Resin 1001-Y-75 epoxy, raw material Epichlorohydrin epoxy, reactive coatings EPON Resin 815C epoxy, rebar coatings Araldite GT 7074 Araldite GT 9545 epoxy, sealants... 

Europe s first rebar coating facility was opened in Cardiff in 1987. 

Coated reinforcement MacroceU formation may be important in the case of epoxy-coated rebars (Section 15.4) in chloride-contaminated concrete if there are defects in the coating and the coated bars are electricaUy connected with uncoated passive steel bars in deeper parts of the structure. Small anodic areas are created at the defect points of coated rebars in contact with chloride-contaminated concrete, while the uncoated passive rebars provide a cathodic surface of much greater size. In these situations the macroceU can result in considerable anodic current densities and can significantly accelerate the attack on corroding sites. This is why coated rebars should be electrically isolated from uncoated bars. 

As far as practice at the construction site is concerned, it should be observed that compared with other types of corrosion-resistant rebars (such as epoxy-coated or galvanized steel), corrosion resistance is a bulk property of stainless steel. Therefore, the integrity of stainless steel is unaffected if its surface is cut or damaged... 

The passive film of galvanized rebars is stable even in mildly acidic environment, so that the zinc coating remains passive even when the concrete is carbonated. The corrosion rate of galvanized steel in carbonated concrete is approximately 0.5-0.8 pm/y, therefore a typical 80 pm galvanized coating would be expected to last over 100 y. [44]. The corrosion rate of galvanized bars remains negligible in carbonated concrete even if a low content of chloride is present. 

K. C. Gear, Y. P. Virmani, Corrosion of non-specification epoxy coated rebars in salty concrete , Corrosion/83, NACE, Houston, Paper No. 114, 1983. 

Coating of rebars. Proprietary products are often applied on the surface of the rebars, to promote adhesion to the repair mortar and to improve the corrosion resistance (often inhibiting properties are also claimed, anti-corrosion coatings ... 

At present, epoxy-coated rebar is the most common corrosion protection system and is used in 48 states. At present, there are nearly 20,000 bridge decks using fusion-bonded epoxy-coated rebar as the preferred protection system. This amounts to nearly 95% of new deck construction since the early 1980s. 

The data from the Concrete Reinforcing Steel Institute (CRSI) shows that more than 3.6 billion kg (4 million tons) of epoxy-coated rebar (150 million m reinforced concrete) were used as of 1998. A significant amount of the epoxy-coated rebar was used in bridge decks. Over time, the formulation of epoxy has been modified to achieve better performance of the epoxy coating. 

Metal-Coated/Clad Rebars and Solid Corrosion-Resistant AUoy Rebars... 

The most promising corrosion-resistant rebars are galvanized (zinc-coated) rebars, stainless steel-clad rebars, and solid stainless steel rebars. Titanium has also been considered as a rebar metal, but its cost is prohibitive although it is highly corrosion-resistant. 

Alternative Means of Protection In addition to the use of coated or alloy rebar, other means to mitigate corrosion of reinforcing steel in bridge structures consist of use of high-performance concrete, corrosion-inhibiting admixtures, or a... 

Multiple Protection Systems Corrosion inhibitors are used in multiple corrosion protection systems in conjunction with epoxy-coated rebars and low-permeability concrete, in particular, for marine applications. Epoxy-coated seven-wire strands are not commonly used for prestressed concrete bridge members. Corrosion inhibitors are used in place of coated seven-wire strands in the prestressed highway construction industry. 

With constant updates in the American Association of State Highway and Transportation Officials (AASHTO) and American Society for Testing and Materials (ASTM) specifications for epoxy-coated rebar, this corrosion protection system will continue to improve. The specifications involve all aspects of fabrication of epoxy-coated rebar. All these will result in improved performance of epoxy-coated rebar and more durable new concrete stmctures. 

Performance of Stainless Steel Rebar in Concrete Corrosion protection of steel rebar can be achieved by (i) selection of corrosion-resistant steel (ii) use of coatings (iii) addition of corrosion inhibitors such as calcium nitrite to concrete mix (iv) addition of concrete sealers (iv) use of membranes (v) use of thicker concrete overlay (vi) cathodic protection. 

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