Corrosion management of concrete structures

This paper reviews the impact of sacrificial anode technologies on the repair of corrosion-damaged bridge structures. The principles of the mechanism and issues affecting its use in connection with concrete structures are outlined. These include maintaining the activity of the anode, accommodating the products of anode dissolution and attaching the anode to the structure. Sacrificial anode systems may be surface systems or embedded discrete systems. Those generally used on bridge structures are discussed: i)thermally sprayed zinc and aluminium, ii) adhesive lined zinc sheeting, iii) discrete anodes in areas of concrete patch repair, iv) discrete anodesin drilled cavities and v) anodes operated in both impressed current and sacrificial modes. Factors affecting the performance of a sacrificial anode system are summarised in a table and comparisons made between the discrete and surface systems. It is suggested that the technology is generallycapable of preventing corrosion initiation and some applications can arrest an active corrosion process. A particular advantage is that no power supply is required and it is suggested that the protection works best when used to target an area of need.