The sonreb method: Critical review and practical aspects

Current regulations require surveys on materials in order to identify one or more representative values of the in-situ concrete strength. In this context, the SonReb method is widespread. It correlates the in-situ concrete strength with the ultrasonic pulse velocity and rebound-hammer index. The method improves the reliability of both non-destructive methodologies that are less reliable if considered separately. However, the method neglects the numerical dispersion of the acquired resistances, making uncertain the reliability of every representative value identified. Uncertainty is inherent not only in the variability of the parameters that determine the values, but also in the use of literature formulations calibrated on “recurring concretes”, i.e. concretes characterized by properties evenly variables (age, w/c ratio, …) that don’t allow wider use. In this work, a critical review of the SonReb method is proposed, through a purely statistical approach with the aid of surveys on some school buildings in the province of Foggia built in the 60s and 80s.