This might be helpful for you in understanding RFI
What is RFI and how to raise it. In which condition RFI should be raised and how to control it. What to do, when no response is recieved from designer. How to control drawings when there are many answered RFI
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OK card is nothing but the permission for pouring of the concrete, its same like a concrete pour card or a checklist which has points to be checked in formwork, reinforcement, some do also include check points for concrete too in it.
You may find relevant checklist in below section
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