Strength of Concrete through Ultrasonic Pulse Velocity and Uniaxial Compressive Strength

Abstract

The noninvasive technique of ultrasonic pulse rate (UPV) is increasingly used in the evaluation of the quality of concrete, providing information about the integrity of structures and preventing possible disasters. Therefore, for its direct application, it is necessary to have a prior correlation between the noninvasive UPV technique and the invasive uniaxial compression resistance (UCS) assay. While correlations have been determined by various authors, each has been given specific conditions and guidelines by the authors because there is no standardized way to perform the correlations. Rather, there are only experimental tests that have generated experimental correlations—both linear and logarithmic—with different graphic shapes. Therefore, this research aims, first, to validate the aforementioned relationship, which allows the compressure resistance of concrete (f'c) to be determined for a given design of concrete mixtures following the American Concrete Institute (ACI. 211.1.). Second, it aims to determine the most accurate trend and the possibly correct form of the correlation plot between the UPV and UCS. In the first instance, 15 plain concrete specimens were designed with an f'c of 28 MPa, whose dosage was carried out following the method of ACI. 211.1. Then, UPV and UCS tests were performed according to regulations in the first 28 days of curing the specimens. Finally, a logarithmic correlation was obtained between the UPV values and the values of the invasive tests for the UCS of concrete. A graphical analysis with some existing correlations of other investigations was then performed, and a similarity in the logarithmic tendency, with a coefficient of determination greater than that of the linear trend, was observed.