Case study of strength evaluation of structural concrete using rebound hammer test

A study was conducted to propose a combined test method for compressive strength evaluation by appropriate correlation between two tests such as rebound hammer test and compression tester test. The rebound hammer test is done on raft basis. According to the number of bounces obtained, the corresponding compressive strength value is determined according to the calibration curve provided by the instrument. The results were verified using a compression tester and the results were reliable. The use of non-destructive testing (NDT) technology such as rebound hammer test was found to be more reliable and suitable for evaluating the quality of concrete structures.

The rebound hammer test, also known as Schmidt hammer, includes a device for measuring the strength of concrete based on the spring loaded mass hitting the concrete surface. The hammer determines the energy hitting the concrete and returns the rebound value. This value can be converted to compressive strength. The ultrasonic pulse speed test evaluates the strength of the concrete by measuring the velocity of the ultrasonic pulse passing through it. This device measures the time it takes for the pulse to pass through the concrete. Faster speeds indicate better quality, while slower speeds may indicate non-uniform concrete consisting of cracks and the like. This speed may also be related to the compressive strength of concrete.

A study was conducted to propose a combined test method for compressive strength evaluation by appropriate correlation between two tests such as rebound hammer test and compression tester test. The rebound hammer test is done on raft basis. According to the number of bounces obtained, the corresponding compressive strength value is determined according to the calibration curve provided by the instrument. The results were verified using a compression tester and the results were reliable. The use of non-destructive testing (NDT) technology such as rebound hammer test was found to be more reliable and suitable for evaluating the quality of concrete structures.

The Schmidt Hammer rebound test has been developed to determine the compressive strength of concrete and has been used to determine the hardness and compressive strength of rock materials (ISRM 1978a). This device is easy to carry and easy to use, it can be used in mold laboratory and workplace. It has been reported that if appropriate test, record and data processing methods are used, it is possible to predict mold performance of a mechanical excavator (taking mechanical properties into account) using a Schmidt hammer ( Göktan & Ayday, 1993).

In many cases, concrete designers use the compressive strength of concrete to determine the strength of the concrete structure. In past articles, we defined the compressive strength of concrete, the observation time, the influence of admixture on strength, and observed the change in the strength of the tested material. In the previous article on compressive strength, the above image was shown. Understanding Concrete Strength The ASTM can be changed with Standard C 94 and American Concrete Association Standard 318 to increase the concrete strength of the concrete being transported while lowering the strength while meeting design strength. In the following example, the design strength is 4000 psi, the concrete manufacturer keeps the mixture quality assurance data over a long period and uses moving average to meet the specified criteria. In this case, ASTM C 94 specification requires a transport strength of 5225 psi, the moving average fulfills this requirement and exceeds it.