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If defects are found during an inspection and the diagnosis highlights the need for repair there are several matters to be considered. Is urgent action required? This may mean that a temporary repair is required followed, when stability and safety are restored, by the application of a longer term repair technique.
Is a repair needed that will restore the element or structure to its original state or will patching be sufficient? Some repair techniques can prevent further deterioration but not restore the structure to its original state. Is re-strengthening in combination with patching sufficient? This could be done by the addition of say external post-tensioning, bonding on steel plates or the use of bonded reinforced plastics plates or tapes.
These systems can also be considered for a structure that as a result of change of use needs to be strengthened. In addition to these considerations, the costs of different repair materials and systems have to be assessed. An important consideration in any such assessment is the amount of service life that the selected repair will safeguard.
There is little point in investing money in a expensive but long lasting repair for a structure that will shortly be replaced as a part of redevelopment. Equally a cheaper shorter life repair that will need to be upgraded regularly would be unlikely to be cost effective for a structure is expected to continue in use for a long period.
Acknowledgement: The Concrete Society
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