Non destructive testing of concrete. Also known as in-place or
in-situ tests.Changes over time and in different exposures can be monitored.References: BS 6089: Guide to assessment of concrete strength in
existing structures;
BS 1881: Testing concrete.
BS EN 13791: Assessment of in-situ compressive strength
in structures and pre-cast concrete components.Provides information on: strength in-situ, voids, flaws, cracks and
deterioration.Rebound hammer test † attributed to Ernst Schmidt after he
devised the impact hammer in 1948. It works on the principle of an
elastic mass rebounding off a hard surface. Varying surface
densities will affect impact and propagation of stress waves. These
can be recorded on a numerical scale known as rebound numbers. It
has limited application to smooth surfaces of concrete only. False
results may occur where there are local variations in the concrete,
such as a large piece of aggregate immediately below the impact
surface. Rebound numbers can be graphically plotted to
correspond with compressive strength.Ref: BS EN 12504-2: Testing concrete in structures.Materials Testing---Concrete