While the conventional approaches for avoiding premature corrosion in reinforced concrete that depend primarily on the control of concrete quality are always recommended, supplementary corrosion avoidance measures can also be worthwhile in certain cases. In this section, some of the numerous available supplementary protection options will be considered. A comprehensive review of the topic is beyond the scope of this chapter, however, and interested readers may find useful sources of further information referred to in Section 5.10.
A general point that should be emphasised here is that effective design for corrosion control normally requires an intelligent combination of measures rather than a single `all-or-nothing’ application of a particular technique. Thus it is always good practice to examine opportunities for reducing the severity of the local environment to which vulnerable parts of a structure will be exposed. This can often be accomplished simply by means of appropriate detailing to avoid the formation of crevices or joints that will retain corrosive liquids and by making provision for free drainage; a number of illustrative examples of good and bad design details have been provided elsewhere (CEB, 1992; Bertolini et al., 2004). Equally it should be borne in mind that if supplementary corrosion protection is to be specified in a form that will not be readily accessible for inspection and treatment in the event of failure, there is a need for convincing evidence of long-term performance relevant to the particular exposure conditions to be provided.