- Author
-
Yeomans, S. R.
- Title
- Considerations of the Characteristics and Use of Coated Steel Reinforcement in Concrete.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
-
NISTIR 5211,
July 1993,
46 p.
- Distribution
- Available from National Technical Information Service
- Keywords
-
building and construction technology
|
reinforced concretes
|
corrosion
|
coated steel reinforcement
|
hot dip galvanized steel
|
fusion bond epoxy coated steel
|
accelerated corrosion testing
|
weight loss
|
chlorides
|
half-cell potentials
|
zinc coating loss
|
rehabilitation
- Abstract
- The corrosion of steel reinforcement in concrete, due in part to the inability of the concrete mass to protect the embedded steel, is a worldwide problem of massive propertions. The damage that results from corrosion, mainly cracking and delamination of the concrete, may significantly reduce the serviceability and structural integrity of reinforced concrete if early repair and rehabilitation is not carried out. These procedures are often quite expensive. While the provision of an adequate cover of a dense impermeable concrete is clearly the best means of protecting reinforcing steel, the use of additional methods of protection in concrete construction are now commonplace. One such method involves the use of coatings on the reinforcement, the two most common of which are epoxy coating and galvanizing. A review is presented of important considerations in the manufacture, specification and performance of coated steel reinforcement. The coating itself, which can be broadly classified as metallic or non-metallic in nature, provides barrier type protection by isolating the steel from corrosive elements in the local environment. In addition, some coating metals which are more anodic than steel afford sacrificial protection in the event that the coating is damaged and the steel substrate is exposed. In the first instance, the physical integrity of the coating, as well as its low reactivity with the environment to which it is exposed, is thus vital to the success of non-metallic coatings such as paints and fusion bonded powders, as well as to noble metal coatings on steel. On the other hand, active metal coatings on steel such as zinc, provide both primary barrier protection and, where the coating is damaged and the substrate exposed, secondary cathodic protection. The long term performance of active metal coatings on steel also depends on the reactivity of the coating metal in the environment to which it is exposed.