The concept behind this method is that the tensile force required to pull a metal disk, together with a layer of concrete, from the surface to which it is attached, is related to the compressive strength of the concrete. The pull out test is normally used for early diagnosis of strength problems. However, it can be used to evaluate the strength of concrete in existing structures. Pull out testing involves attaching a small piece of equipment to the exterior bolt, nut, screw or fixing. This is then pulled to the designated stress load level to determine how strong and secure the fixing is. It is relatively easy to use and if relationship to strength is established, the method can deliver robust test results. It involves crushing and damaging concrete.
Design codes: UNI EN 12504-3