The LOK-TEST system is used to obtain a reliable measurement of the in-place compressive strength of concrete in newly cast structures in accordance with the pull out test method described in ASTM C900, BS 1881:207, or EN 12504-3
An insert with a steel disc, 25 mm in diameter at a depth of 25 mm, is cast into concrete. Once the concrete has hardened, the disc is pulled centrally against a 55 mm diameter counter pressure ring bearing on the testing surface. The force F required to pullout the insert generates compression stresses in the strut between the disc and the counter pressure ring. Loading is performed either to a required force, in which case the test is nondestructive, or to the peak-load, which results in a slightly raised, 55-mm diameter circular crack on the surface. If pulled out, the conical hole can be easily patched with a repair non-shrink mortar.
Pull out test.