Non-destructive tests give information about the properties of the concrete of a structure, but the reliability of the evaluation of those properties depends on the experience of the professional that carries out the tests and the curves employed to correlate the measured values with the properties of the investigated concrete. The main objective of this study was to supply engineers with correlation curves that make it possible to evaluate, by using non-destructive test results, the compressive strength and the modulus of elasticity of ready-mixed concretes used in Rio de Janeiro. Test specimens cast with concretes used in several constructions and supplied by different ready-mixed concrete producers were tested. These concretes had, in general, nominal fck value of 25 MPa or 30 MPa. Aiming to include concretes with strength varying within a wider range and made with the two types of typical coarse aggregates of Rio de Janeiro, test specimens cast in the laboratories of two readymixed concrete producers were tested. In these concretes, the water-cement ratio (0.40 to 0.60) and the petrographic characteristic of the coarse aggregate were varied. Compressive strength and modulus of elasticity tests, ultrasonic pulse velocity, rebound hammer and penetration resistance tests were carried out, at the ages of 3, 7, 14, 28 and 90 days. The correlation curves obtained from the analysis of the results of all those tests are presented here. When only one non-destructive test was used, the rebound hammer was the one that led to the best estimation of compressive strength and the combination of that test with the penetration resistance test improved the accuracy of the evaluation. If modulus of elasticity tests cannot be carried out, the ultrasonic pulse velocity test can be an interesting option to evaluate that property.
correlation curves; nondestrutive tests; ready-mixed concrete