Often, existing concrete structures will need to be examined and tested to ensure the concrete remains of adequate strength and durability. This test is used to determine the compressive strength of a concrete core, which has usually been extracted from an existing structure. The value of compressive strength can then be used in conjunction with other measured properties to assess the condition of the concrete.
Extraction of concrete cores, achieved by rotary drilling using a diamond tipped hollow barrel, serve as a means of taking a sample of concrete which can then be used to determine various physical properties, but most commonly compressive strength.
Cores can generally be extracted from wherever access allows, and would include floor slabs, walls and columns. 10cm diameter cores, generally afford the minimum diameter required for a representative sample and require less reinstatement than larger diameter cores. 15cm diameter cores will generally give more representative samples than smaller diameters but require more reinstatement.
As per leaflet
Diamond Impregnated core drills of required dia and length, Masonry core cutter, Grinding and Lapping Machine