Introduction |
Stainless Steel
Reinforcing Bars (Rebar) Deterioration of reinforced concrete caused by corrosion of the carbon steel reinforcing bars (rebars) is a worldwide problem. The corrosion product ("rust") occupies a greater volume than the original steel bar and this creates a pressure which causes cracking and subsequent spalling of the surrounding concrete.
Corrosion of carbon steel rebars is greatly accelerated when chlorides are present in the concrete (along with the requisite moisture and oxygen levels to sustain the corrosion reactions). In some parts of the world, chlorides may be incorporated into the original mix due to their presence in the sand, aggregate or water. Most often, chlorides penetrate through the "cover" when the external surfaces of the concrete are exposed to seawater, marine atmospheres or de-icing salts. Several methods are currently employed in an attempt to reduce the corrosion of carbon steel rebars. These include: rebar coatings (fusion-bonded epoxy, galvanizing); increased concrete cover; reduced water/cement ratios; corrosion inhibitors added to the concrete mix, concrete sealers, cathodic protection; and concrete coatings or membranes. However, there is increasing interest in the use of reinforcing materials that have inherently good corrosion resistance, thus minimizing the need for maintenance and monitoring of the structure. Stainless steels are such materials and they have been used as concrete rebars in Europe, North America, Asia, Australia and Africa. |
