New predictive models to evaluate concrete compressive strength using the SonReb method

An accurate assessment of the concrete compressive strength is a fundamental step towards evaluation of existing reinforced concrete structures under gravity and seismic loads. It can be conducted using destructive and nondestructive methods. Data obtained with destructive methods (core sampling) and non-destructive methods (sclerometric, ultrasonic and combined sonic rebound) have been collected by the Regional Seismic Department of Tuscany from a large number of RC structures, built between the 50s and 80s. The database, which includes crushing strength, ultrasounds velocity and rebound index, has been adopted to check the predictive effectiveness of the currently available analytical models. On the basis of the same database, new models have also been calibrated and proposed herein. They have been validated on a further database, not included in the one used for models calibration. The paper takes advantage of a large database to check the effectiveness of the available prediction models, and to propose new relationships, which are very effective for predicting the concrete strength of Italian RC buildings made in the latter decades of the XX century. The paper faces important issues of concrete characterization, beyond simply providing an original set of data.