The rebound hammer was the first hammer that was created to measure the properties of rock or concrete. There are different versions of the hammer and this enables the company to provide the type of hammer that all customers want for whatever specific job they are doing. The hammer tests the surface hardness of concrete, and although some people believe that this can be converted to compressive strength, this is not acceptable.
The test for the acceptance of concrete must be carried out with different equipment. If the rebound hammer is used, the reading will not be correct and there may be serious consequences later on. The test results can be altered by a number of factors. Moisture content and surface smoothness are just two of the factors that can change it, and they test can only give an estimate of concrete strength.
The manual-testing tool is the instrument used for testing hardened concrete. This does not damage the concrete in any way, and it is an easy piece of equipment to use. It quickly assesses the results and is the most popular way of carrying out this test. Also known as the Schmidt or Swiss hammer, it carries out a very important function. While it is a good instrument to use, it can not be used in isolation.
It does not give 100% of the information that is needed and any tests should be followed up by any other non-destructive test to ensure that the best results are obtained. The procedure to take a reading is as follows. Make sure the surface of the concrete is clean. It must also be smooth, and a rough surface can produce an inaccurate reading. Take 12 readings in the shape of a diamond around the area that you are testing. This is easy to do, as all that is needed is for the tool to be placed against the concrete and the sprung mass is released.
There is section at the side of the hammer and the percentage rebound is shown on this. It is also possible for different users to produce slightly different readings, so anyone assessing the results should learn how each reader's records. There should not be a big difference if the machine is used properly but it will be noticeable. As a result of test carried out in Delphi, there has been a slight issue found with this machine and that is that there is a problem with the correction method regarding the direction of rebound.
hammer rebound tests taken horizontally Showed values LOWER than the vertical ones once the correction Had been made. The manufacturers believe they have the solution but some users are not sure. Finally, one or two other factors may have an influence on the reading. If there are slight gaps just below the concretes surface it will affect the reading. It may be too small to be an issue, but by taken numerous readings, you will be able to be assured that it is not a wide spread problem.