Rebound Hammer Test

The rebound (Schmidt) hammer is one of the oldest and best known methods of comparing the concrete in various parts of a structure and indirectly assessing concrete strength. Rebound Hammer Test 1The hammer weighs about 1.8 kg and is suitable for use both in a laboratory and in the field. The rebound of an elastic mass depends on the hardness of the surface against which its mass strikes.


  • Finding the elastic properties like compressive strength
  • Assessing –  the uniformity of concrete.
  • Determining variations of strength within a structure


  • IS 13311, IS 516: 1959Rebound Hammer Test 2
  • BS EN 12504-2
  • ASTM C805


  • Before commencement of a test, the rebound hammer should be tested against the test anvil, to get reliable results,
  • Apply light pressure on the plunger. it will release it from the locked position and allow it to extend to the ready position for the test.
  • Press the plunger against the surface of the concrete, keeping the instrument perpendicular to the test surface. Apply a gradual increase in pressure until the hammer impacts
  • Take the average of about 15 readings.


  • Hammer has to be used against a smooth surface, preferably a formed one.
  • If the concrete does not form part of a large mass any movement caused by the impact of the hammer will result in a reduction in the rebound number
  • Not a very good test for old concrete and low strength concrete.
  • Moisture content affects the readings significantly.
  • Type of cement also affects the readings.
  • Surface Carbonation increases the hammer reading significantly than it actually is.