STRENGTH EVALUATION OF IN-SITU CONCRETE BY REBOUND HAMMER AND CORE TESTING

This paper describes the results of an extensive field investigation where the quality of in-place concrete flatwork was evaluated. Nondestructive testing (NDT) was carried out using ultrasonic pulse velocity and rebound hammer techniques to establish a correlation with compressive strengths of core tests. The rebound hammer/core correlation formed the basis of a recommendation on the acceptance or rejection of the in-situ concrete. The ultrasonic pulse velocity UPV testing was primarily used to establish concrete uniformity. Limited freeze-thaw testing was carried out to determine the potential long-term durability performance. In order to minimize the effects of surface preparation on the test results, considerable time was spent to determine the optimum grinding procedure.