Cores are cut using a drill with a hollow barrel tipped with industrial diamonds. The whole rig has to be firmly fixed in position by weights, anchor bolts, vacuum pads, or bracing against other parts of the structure. The preferred core diameter for strength testing is not defined in BS EN 12504-1, BS EN 13791, or BS 6089 but the diameter should be at least 3.5 x the maximum aggregate size. Sometimes even smaller diameter cores have to be used for strength testing. In this case, the strength results can be more variable and a greater number of cores should be extracted.
For strength testing, the length to diameter ratio should be between 1 and 2 and preferably between 1 and 1.2. When cores are received in the laboratory they may be examined for degree of compaction, cracks, voids, honeycombing, and the presence of reinforcement.