Concrete, structural, corrosion

T. Pastore, P. Pedeferri, Cathodic protection of new and old rein-forced-concrete structures . Corrosion Science, 1993, 35, 1633-1639. 

L. Bertolini, P. Pedeferri, Field application of cathodic prevention on reinforced-concrete structures . Corrosion 96, NACE, Houston, paper 312, 1996. 

J. E. Bennet, C. Firlotte, A zinc/ hydrogel system for cathodic protection of reinforced-concrete structures . Corrosion 96, Nace, paper 316, 1996. 

The potential of the corroding surface can be monitored periodically by means of a reference electrode. One such example is the corrosion potential measurement of reinforced steel rebar in concrete structures. Corrosion of the steel in reinforced concrete is a major factor in the deterioration of highway and bridge infrastructure. A survey of the condition ofa reinforced concrete structure is the first step toward its rehabilitation. A rapid, cost-effective, and nondestructive condition survey offers key information to evaluate the corrosion, aids in quality assurance of concrete repair and rehabilitation. 

Bennett, J.E. and Mitchell, T.A. (1992). Reference Electrodes for Use with Reinforced Concrete Structures. Corrosion 92, Paper 191, Nashville. 

Broomfield, J.P. (2000). Results of Long Term Monitoring of Corrosion Inhibitors Applied to Corroding Reinforced Concrete Structures. Corrosion 2000. Paper No. 791. 

Bennett, J.E., Schue, T.J. and McGill, G. (1995) A Thermal Sprayed Tifanitim Anode for Cathodic Protectioti of Reinforced Concrete Structures, Corrosion 95 Paper No. 504, NACE International, Houston, TX. 

A serious problem which is faced by building industry is rebar corrosion in concrete. In steel reinforced concrete structure, corrosion attack is prevented by high alkaline environment in... 

The failure of a concrete structure is of course not confined to catastrophic collapse. A concrete structure has failed or reached the end of its serviceability life when it is no longer capable of fulfilling its design functions, e.g. leak-tightness or as a barrier against deleterious elements which may cause corrosion. 

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. 

Cathodic protection cannot work with prestressed concrete structures that have electrically insulated, coated pipes. There is positive experience in the case of a direct connection without coated pipes this is protection of buried prestressed concrete pipelines by zinc anodes [38], Stability against H-induced stress corrosion in high-strength steels with impressed current has to be tested (see Section 2.3.4). 

The passivating action of an aqueous solution within porous concrete can be changed by various factors (see Section 5.3.2). The passive film can be destroyed by penetration of chloride ions to the reinforcing steel if a critical concentration of ions is reached. In damp concrete, local corrosion can occur even in the presence of the alkaline water absorbed in the porous concrete (see Section 2.3.2). The Cl content is limited to 0.4% of the cement mass in steel-concrete structures [6] and to 0.2% in prestressed concrete structures [7]. 

The decision to cathodically protect reinforced concrete structures depends on technical and economic considerations. Cathodic protection is not an economic process for small area displacements of the concrete due to corrosion of the reinforcing steel arising from insufficient concrete covering. On the other hand, the... 

Reinforced concrete structures that are fully immersed or buried in a corrosive environment may generally be protected using conventional cathodic... 

In addition, further oxidation and cathodic reactions lead to the production of oxides and oxyhydroxides of Fe (III), which produces a low-permeability, passive film that slows down the corrosion rate considerably. Where corrosion can continue (by depassivation), the expansion of corrosion products at the cement-steel interface and the subsequent spalling of cover concrete can occur. Many examples of this can be seen in concrete structures. 

The most widely used anodic inhibitors are calcium and sodium nitrite, sodium benzoate and sodium chromate. With the exception of calcium nitrite, no other chemical is available in North America as a proprietary product. Nitrites have been used in the USA for more than 14 years and for nearly 40 years in Europe. Calcium nitrite is marketed as a non-chloride accelerator, as well as a corrosion inhibitor. For 25-30% solids in solution, dosage rates range from 2 to 4% by weight of cement depending on the application [50]. Calcium nitrite has been used in bridges, parking and roof decks, marine and other prestressed concrete structures that are exposed to chloride attack. 

Sodium benzoate has been used singly in concrete structures exposed to severe corrosion attack and also in combination with sodium nitrite in cement slurries to paint on steel reinforcement before embedment in concrete [65, 66]. Work done by Lewis et al. showed that concrete to which 2% benzoate was added produced setting times that were similar to control concretes, but the compressive strengths decreased by about 40% [66, 67]. Lewis et al. [66] however have concluded that sodium benzoate has a more persistent inhibitory effect than calcium nitrite. 

Latex-modified mortars and concretes have become promising materials for preventing chloride-induced corrosion and for repairing damaged reinforced concrete structures. In Japan and the USA, latex-modified mortar is widely used as a construction material in bridge deck overlays and patching compounds, and for finishing and repairs [99]. Polymer-cement hydrate-... 

Acta Metallurgica et Materialia Cement and Concrete Research Composite Structures Computers and Structures Corrosion Science Engineering Failure Analysis Engineering Fracture Mechanics European Journal of Mechanics A B International Journal of Fatigue International Journal of Impact Engineering International Journal of Mechanical Sciences International Journal of Non-Linear Mechanics International Journal of Plasticity... 

Metal or steel reinforced concrete structures which are not in themselves inert to chemical attack (corrosion) from the environment in which they are designed to serve can very rarely be protected by a metallic surfacing. The normal protection under such conditions will be supplied by a nonmetal, often a coating. Each nonmetal so used has its own limitations—chemical or thermal—which must be considered. Therefore, in many cases, a combination of two or more nonmetals is required to provide the necessary ultimate protection to the steel or concrete. 

Structural tile can be used as a lining in a metal vessel similar to a brick lining, as shown in Figure 51-2, but is more commonly used to build relatively inexpensive reinforced concrete structures with corrosion resistant interior and exterior surfaces. Two different types of wall construction are shown in Figures 51-3 and 514. In Figure 51-3 the tile are used in their block form. The wall thickness is obviously limited by the width of the block. In Figure 514, the tile is split to construct a wall of any practical thickness. 

Other workers have published improved procedures for inspecting both reinforced concrete and prestressed concrete structures with regard to determination of the embedded steel components [110]. A prototype ultrasonic procedure was developed to determine the condition of prestressed and pretensioned tendons in concrete. The application of electrochemical surface-mounted systems for estimating the rate of corrosion of reinforcing steel and other embedded steel components in large concrete structures was described using this technique. 

In the case of a concrete structure, the presence of steel reinforcements can further complicate the system by causing a local heterogeneity since they constitute in terms of dose rate (driving of the radiolysis) or by the influence of iron ionic species on radiolysis at the interface with the cement paste. Although still not very well-studied, the resulting radiolysis-corrosion coupling (as a function of temperature) is identified as the only aspect which could possibly affect the concrete durability under radiation [1]. 

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