Impact hammers / Schmidt hammer

NDT Non-destructive testing method in hardened concrete. 
  
A rebound hammer, also known as a rebound hammer, is used to measure the surface hardness of concrete, and the development of surface strength.  

• The rebound hammer works by dropping a spring-loaded hammer against the concrete surface and measuring the rebound. The amount of rebound gives an indication of the surface hardness of the concrete.
• It is mainly used to estimate the compressive strength of concrete in situ without destroying the structure. This is useful for quality control and assessment of existing concrete structures.
• The rebound hammer is easy to use, fast and gives immediate results. It is also portable and can be used on construction sites.