ACI
ACI 562
Code Requirements for Assessment, Repair, and Rehabilitation of Existing Concrete Structures
The code that covers what to do with concrete that already exists, which is most of an integrity engineer's work. It sets out the assessment procedure, the basis for deciding whether an existing structure is adequate, the compatibility requirements between repair material and substrate, and the durability design of the repair itself. Its central discipline is that a repair must be designed against a diagnosed cause: patching corrosion-damaged concrete without addressing chloride ingress or carbonation produces an incipient anode and a faster second failure.
This is an explanation, not the standard. PipingInspector is not affiliated with ACI and reproduces no part of the document. Always work to the current edition of the standard itself and to your project specification.