Reinforcement coating

Glass pipe can be furnished with an epoxy-resin coating reinforced with woven glass fiber to protect it from abuse. Equipped with special ball couphngs, this may be used for 1-MPa (150-lbf/in ) pressure. 

FIGURE 6.21 J-V (a), L-V (b), and E-V (c) characteristics measured for OLEDs made with a commercial ITO-coated 1.1-mm rigid glass substrate and a low-temperature ITO-coated reinforced ultrathin glass sheet. 

Polymers of N, N, N, A-diallyldimethylammonium chloride (DADMAC) (and its copolymers with acrylamide) are allyl resins in terms of the monomers used but are very different in properties since they are not crosslinked. Cyclopolymerization is the mode of reaction (Sec. 6-6b) and the polymers are water-soluble. Applications include potable and wastewater treatment (flocculation aid) and paper and textile industries (antistatic coating, reinforcement, color removal). 

Virmani, Y.P., Clear, K.C. and Pasko, T.J. (1983). Time to Corrosion of Reinforced Steel in Concrete Slabs, Vol. 5, Calcium Nitrite Admixtures or Epoxy Coated Reinforced Bars as Corrosion Protective Systems, FHWA-RD-83-012, FHWA, US Department of Transportation, 71. 

Large sizes Concrete tunnel with coated reinforcement bar. 

Concrete structure constructed with coated reinforcement with polyurethane coating on surface. 

Tank bottom corrosion is a function of the water layer that exists on the bottom of most tanks. The presence of sulfate-reducing bacteria, characterized by shiny pits, is more of a problem in heavy stocks because oxygen cannot reach the bottom. The most common way to control tank bottom corrosion is to drain the water from the tank bottom periodically. Both epoxy and polyester coatings reinforced with chopped glass fiber have been used successfully in places where severe corrosion has occurred. For new tanks in which corrosion is expected, coal-tar epoxy is usually specified for the bottom. Corrosion of the underside of the tank bottom does not usually occur if a proper oH and sand base is used. Cathodic protection is used when water cannot be prevented from contacting the underside of the tank bottom. 

It is essential to determine the yield of each major product rather precisely and at different values of the various operating parameters, mainly temperature, residence time, and pressure. Many studies are incompletely documented, considering only gas or liquid phase products, without mention of residues or mass balances. Moreover, in practice the product yield of pyrolysis is reduced by losses inherent to consecutive purification. Inevitable losses occur further during storage, transfer, and separation. Moreover, each raw material as a rule contains nonproductive constituents, such as some moisture, metal inserts, coatings, reinforcement agents, or fillers. These loss factors explain why laboratory data may lead to overly optimistic views regarding possible industrial yields ... 

Several studies were devoted to EPD of hydroxyapatite coatings reinforced with either CNTs (Kaya, 2008 Lin et al., 2008 Zhang et al., 2011), chitosan (Mah-moodi et al., 2013) or alumina (Wang, Ni and Huang, 2008). Other ceramics of importance for biomedical applications such as alumina (Salman, Jassim and Al-Zubaydi, 2011) and zirconia (Ananth et al., 2013) were deposited by EPD onto Ti alloy surfaces. 

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. 

Requirements for epoxy-coated reinforcing bars are reported in different international standards and recommendations the first dates back to 1981 (ASTM A775-81) and more recent national standards in European countries are based on it, even though their requirements are much more rigorous. 

Very high corrosion rates in the vicinity of defects in the coating can occur in the presence of macrocells. A typical situation is that of stractures in which epoxy-coated reinforcement in contact with chloride-contaminated concrete is coupled to non-coated reinforcement embedded in concrete that is uncontaminated or contains a level of chlorides below the critical level. In this case, the passive non-coated... 

P. Schiessl, C. Reuter, Coated reinforcing steels development and applications in Europe , Corrosion/91, NACE, Houston, Paper No. 556, 1991. 

K. C. Clear, Effectiveness of epoxy-coated reinforcing steel , Concrete International, 1992, 5, 58—62. 

Epoxy coatings cost approximately 4.7-5.3/l while antifoulants are more expensive at 11.8-21.1/1. Environmental regulations have led to decreased amount of chemicals released from industrial installations along waterways, especially corrosives such as chlorine. The materials of construction for some water structures have also changed. Piers and docks are no longer constructed with wood, but instead are constructed with steel-reinforced concrete. To improve the lifespan of the structure and prevent corrosion of reinforcing steel, fusion-bonded epoxy-coated reinforcement or corrosion-inhibiting admixtures are sometimes utilized in the concrete mix. 

Bituminous coatings reinforced with chlorinated rubber are used in silos, tanning pits, drinking water containers, and on ships hulls (on the underwater part). Bituminous substances for coatings are supplied as special products that are free from carcinogenic constituents. 

A.M. Zayed, A.A. Sagues, Corrosion at surface damage on an epoxy-coated reinforcing steel, Corros. Sci. 30 (1990) 1025-1044. 

On the one hand the coating technology offers the opportunities to achieve a higher tensile strength combined with a high durability. On the other hand state of the art limits the coated reinforcements for flat elements or need cost effective production steps. 

We will return to the subject of pitting corrosion later. It is related to the problems of coated reinforcement and to the black rust phenomenon discussed earlier. 

The CEN standard states in its scope that it refers to atmospherically exposed normal reinforced and prestressed concrete as uncoated and organic coated reinforcement. It is more detailed than the NACE standard (34 pages vs. 12) with far more on the assessment and repair of the structure and installation procedures. The criteria are buried in Section 8 of the standard. 

Cathodic protection of epoxy coated reinforcing steei... 

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