Extending residual service life of steel reinforced structures by the use of galvanic anodes

摘要

Corrosion of steel reinforcement, usually caused from chloride contamination, leads to cracking and spalling of the cover concrete. If patch repairs are carried out, they can often lead to the transfer of corrosion sites beyond the perimeter of the repairs owing to a phenomenon known as incipient anode formation. The use of galvanic anodes within the patch repairs has been successful over the last 14.5 years in avoiding this phenomenon. Furthermore, galvanic anodes used in a grid configuration have also been shown to control reinforcement corrosion. In both cases the use of galvanic anodes had significantly extended the residual service life of the steel reinforced concrete component or structure. Study of monitored site results and complementary laboratory investigations have increased the understanding of the performance of galvanic anodes in concrete resulting in the development of better performing units. This has widened the scope for the application of galvanic anodes for remediation against corrosion initiation or for controlling corrosion by its initial arrest followed by prevention of further corrosion. This paper, first, gives examples of achieving enhanced steel reinforced concrete durability by the use of galvanic anodes, presenting and analysing results of discrete anode systems in patch repairs as well as in global corrosion control. Secondly, it presents new studies indicating how corrosion can be stopped over relatively short periods and, with subsequent use of galvanic anodes at relatively low current densities, enable planned effective residual service life extension of structural components.