Inspection

Immediately after stripping the formwork, all concrete shall be carefully inspected and any defective work or small defects either removed or made good before concrete has thoroughly hardened. In case of doubt regarding the grade of concrete used, either due to poor workmanship or based on results of cube strength tests, compressive strength tests of concrete on the basis of 16.3 and / or load test may be carried out.

Core Test

The points from which cores are to be taken and the number of cores required shall be at the discretion of the engineer-in-charge and shall be representative of the whole of concrete concerned. In no case, however, shall fewer than three cores be tested.
Concrete in the member represented by a core test shall be considered acceptable if the average equivalent cube strength of the cores is equal at least 85 percent of the cube strength of the grade of concrete specified for the corresponding age and no individual core has a strength less than 75 percent.
In case the core test results do not satisfy the requirements or where such tests have not been done, load test may be resorted to.

Load Tests on Parts of Structures
Load tests should be carried out as soon as possible after expiry of 28 days from the time of placing of concrete. The structure should be subjected to a load equal to full dead load of the structure plus 1.25 times the imposed load for a period of 24 hours and then the imposed load shall be removed. The deflection due to imposed load only shall be recorded. If within 24 hours of removal of the imposed load, the structure does not recover at least 75 percent of the deflection under superimposed load, the test may be repeated after a lapse of 72 hours. If the recovery is less than 80 percent, the structure shall be deemed to be unacceptable. If the maximum deflection in mm, shown
during 24 hours under load is less than 40 l2 / D, where l is the effective span in m and D, the overall depth of the section in mm, it is not necessary for the recovery to be measured and the recovery provisions will not apply. Other non-destructive test methods may be adopted, in which case the acceptance criteria shall be agreed upon between the engineer-in-charge and the contractor and the tests shall be done under expert guidance.