Assessing the strength of reinforced concrete structures through Ultrasonic Pulse Velocity and Schmidt Rebound Hammer tests

The experimental studies using Ultrasonic Pulse Velocity and Schmidt Rebound Hammer as Non-Destructive Tests (NDT) were presented in this paper to establish a correlation between the compressive strengths of compression tests and NDT values. These two tests have been used to determine the concrete quality by applying regression analysis models between compressive strength of in-situ concrete on existing building and tests values. The main members of an existing structure including column, beam and slab were included in the study. The relationship between compression strength of concrete collected from crashing test records and estimated results from NDT’s records using regression analysis was compared together to evaluate their prediction for concrete strength. The test results show that the rebound number method was more efficient in predicting the strength of concrete under certain conditions. A combined method for the above two tests, reveals an improvement in the concrete strength estimation and the latter shows better improvement. Applying combined methods produces more reliable results that are closer to the true values. The resulting strength calibration curves estimation was compared with other results from previous published literatures.  Key words: Non Destructive testing (NDT), Schmidt Rebound Hammer (SRH); Ultrasonic Pulse Velocity (UPV), NDT combined method, compressive strength, regression analysis.