Corrosion control reinforcing steel

From the point of view of cost, it is preferable to use stainless steel-clad rebar instead of stainless steel rebar. It is estimated that the use of stainless steel-clad rebar provides an expected life of 50 years. The cost of stainless steel cladding can vary depending on the raw material market prices just like solid stainless steel, but also depends on the cladding manufacturer, cladding thickness, and the chosen grade of stainless steel. With proper quality control, stainless steel-clad rebar promises to be an effective means of control for bridge deterioration because of corrosion of reinforcing steel. 

The mechanism of material degradation in sewer pipes is similar to potable water systems. The internal corrosion may be more severe than in potable water because the wastewater is not clean. The winterizing treatments of roads are a source of chloride, which comes into contact with the pipe. Cement-based pipe experiences corrosion of reinforced steel. The corrosion control method consists of using thicker pipe walls, which provide for larger corrosion tolerance and a longer design life. 

Cathodic protection is used widely for the protection of submerged steel in waterfront structures. It also can provide considerable benefit in the intertidal zone and can even reduce the usually high corrosion rate experienced at the boundary between the intertidal zone and the splash and spray zone. Cathodic protection also is used to prevent corrosion of the soil side of steel in marine structures such as sheet steel bulkheads. Cathodic protection also is effective in the control of the corrosion of reinforcing steel in concrete in all exposure zones in waterfiont structures. Particularly for impressed current systems, it is important to select materials for the cathodic protection system components such as rectifiers and junction boxes with consideration of the environment to which they will be exposed. When considering cathodic protection, periodic inspection and maintenance is required for proper system operation. The costs for inspection and maintenance must be considered in the overall cost of cathodic protection. While there are no specific standards for cathodic protection of piers and docks, information in NACE RP0176 (Corrosion Control of Fixed Offshore Platforms Associated with Petroleum Production) and NACE RP-0187 (Design Considerations for Corrosion Control of Reinforcing Steel in Concrete) contain information that is applicable to marine piers and docks. 

Corrosion Inhibitors. Steel-reinforcing wire and rods embedded in concrete containing quinoline or quinoline chromate are less susceptible to corrosion (72) (see Corrosion and corrosion control). Treating the surface of metals with 8-hydroxyquinoline [148-24-3] makes them resistant to tarnishing and corrosion (73). Ethylene glycol-type antifreeze may contain quinoline, 2-chloro-, 4-amino-, 8-nitro-, or 8-hydroxyquinoline to prevent corrosion (74). 

Finally, it is necessary to point out that although a particular method of corrosion control may be quite effective for the structure under consideration it can introduce unforeseen corrosion hazards elsewhere. Perhaps the best example is provided by cathodic protection in which stray currents (interaction) result in the corrosion of an adjacent unprotected structure or of steel-reinforcement bars embedded in concrete a further hazard is when the cathodically protected steel is fastened with high-strength steel bolts, since cathodic protection of the tatter could result in hydrogen absorption and hydrogen cracking. 

NACE Standard RP 0187, Design considerations for corrosion control of reinforcing steel in concrete, NACE Int., Houston, Texas, 2000. 

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. 

Salt-induced reinforcing steel corrosion in concrete bridges is a serious problem and an economic burden. Although the positive effect of corrosion protection measures can be seen on individual cases, there are many bridges (thousands) without corrosion control. 

Linear polarization measurements are performed by scanning a range close to the corrosion potential. These experiments provide nondestructive information about the corrosion process occurring on reinforcing steel. The polarization resistance (Rp) of a corroding system under activation control is defined as ... 

Impressed current anodes have very slow or controlled consumption rates when the anodic reaction occurs on the anode surface. As the reaction consumes alkalinity (equation (7.5)) and generates acid (equation (7.6)), it can attack the anode and the concrete. The level of current is therefore important in maintaining a good anode to concrete bond. Types of anode are described later. The function of the anode is to spread the current to all areas to be protected having converted the electrical current from the transformer rectifier (DC power supply) to an ionic current that flows from the anode to the cathode so that the cathodic reaction will occur on the reinforcing steel surface, suppressing corrosion. 

Broomfield, J.P. (1995). Field measurements of the corrosion rate of steel in concrete using a microprocessor controlled guard ring for signal confinement . In N.S. Berke, E. Escalante, C. Nmai and D. Whiting (eds). Techniques to Assess the Corrosion Activity of Steel Reinforced Concrete Structures, American Society of Testing and Materials, STP 1276, Philadelphia, PA. 

Technical Alert Criteria for the Cathodic Protection of Reinforced Concrete Bridge Elements. Pre.sents results and recommendations based on the investigation of control criteria used to nrea.sure corrosion rates of steel in a concrete environment. 14 pages. SHRP-S-359, 5... 

Also, NACE Standard Recommended Practice-Design Considerations for Corrosion Control of Reinforcing Steel in Concrete (RP0187) contains recommendations for corrosion monitoring systems for steel in concrete. 

Waterfront structures are exposed to a variety of marine environments. The resistance of materials to each of these environments may vary considerably, as weU as appHcabil-ity of various forms of corrosion control in mitigating the anticipated corrosion. The waterfront environment can be divided into five exposure zones sediment, immersion, intertidal, splash/spray, and atmospheric. In most cases, a single type of material will be used for the sediment, immersion, and intertidal zones. In some cases another material may be used for the splash and spray and atmospheric zones of the structure. An example of this would be the use of a reinforced concrete deck over steel pilings. Due to differences in corrosion activity between these zones, the corrosion performance of many materials is substantially different when exposed to two or more of these zones. Figure 1, taken from Ref 4, shows the result of a classical experiment where the corrosion of a continuous strip of... 

Maintenance and Rehabilitation Considerations for Corrosion Control of Existing Steel-Reinforced Concrete Structures... 

NACE Standard (1987), Design Consideration for Corrosion Control of Reinforced Steel in Concrete, RPOl 87-87. Houston NACE. 

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