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Non-destructive testing (NDT) techniques are crucial in making informed decisions about reconstructing or repairing building structures. The SonReb method, a combination of the rebound hammer (RH) and the ultrasonic pulse velocity (UPV) tests, is widely used for this purpose. To evaluate the compressive strength, C S , of the concrete under investigation, the ultrasonic pulse velocity V p and the rebound index R must be mapped to the compressive strength C S using a suitable conversion model, the identification of which requires supplementing the NDT measurements with destructive-type measurements (DT) on a relatively large number of concrete cores. An approach notably indicated in all cases where the minimization of the number of cores is essential is to employ a pre-existing conversion model, i.e., a model derived from previous studies conducted in the literature, which must be appropriately calibrated. In this paper, we investigate the performance of Gaussian process regression (GPR) in calibrating the pre-existing SonReb conversion models, exploiting their ability to handle nonlinearity and uncertainties. The numerical results obtained using experimental data collected from the literature show that GPR calibration is very effective, outperforming, in most cases, the standard multiplicative and additive techniques used to calibrate the SonReb models. [ABSTRACT FROM AUTHOR]

Determining the compressive strength of concrete is important in all phases of construction and in diagnosing the technical condition of existing reinforced concrete buildings and facilities during their service. In this article, the author presents the experimental results from research conducted over 6 years. The following non-destructive methods were used in the tests—elastic rebound, ultrasonic, SonReb and destructive methods, and the results of the latter were used as a reference. The tests were carried out on specimens prepared on the day of laying the concrete mix in the reinforced concrete beams or cores taken from the beams. The results of the determination of the probabilistic compressive strength using the different methods at concrete ages of 28, 244, 280, 293, 342, 1126 and 1926 days, are presented. The relative error, predicted strength and accuracy were determined and compared. Isocurves were drawn to determine the compressive strength for each point of a reinforced concrete structure based only on measurements obtained using non-destructive methods. The results obtained via SonReb and via the method assessing ultrasonic pulse velocity and its relationship to the dynamic and static modulus of elasticity were the closest to the reference compressive strength values. [ABSTRACT FROM AUTHOR]

This document discusses the results obtained in the estimation of compression strength through the readings of the rebound hammer and ultrasonic pulse velocity on 9 columns of reinforced concrete. The estimation was performed by applying different SonReb models. The objective of the study is to evaluate which of the applied models is more consistent with the compression resistance value of 27.0 MPa obtained by press-breaking assay, for concretes manufactured with Ordinary Portland Cements P-35 (Type I) of domestic production and aggregates from Cuban quarries. The results obtained showed that the models proposed by RILEM and Tanigawa et al. were closest to the reference value with percentage difference below 4%. This research will allow the performance of non-destructive tests with more accurate results, in the restoration processes of the Historic Center of Havana, Cuba. [ABSTRACT FROM AUTHOR]

Determining the compressive strength of concrete is important in all phases of construction and in diagnosing the technical condition of existing reinforced concrete buildings and facilities during their service. In this article, the author presents the experimental results from research conducted over 6 years. The following non-destructive methods were used in the tests—elastic rebound, ultrasonic, SonReb and destructive methods, and the results of the latter were used as a reference. The tests were carried out on specimens prepared on the day of laying the concrete mix in the reinforced concrete beams or cores taken from the beams. The results of the determination of the probabilistic compressive strength using the different methods at concrete ages of 28, 244, 280, 293, 342, 1126 and 1926 days, are presented. The relative error, predicted strength and accuracy were determined and compared. Isocurves were drawn to determine the compressive strength for each point of a reinforced concrete structure based only on measurements obtained using non-destructive methods. The results obtained via SonReb and via the method assessing ultrasonic pulse velocity and its relationship to the dynamic and static modulus of elasticity were the closest to the reference compressive strength values.