Combined non-destructive methods applied to normal-weight and lightweight-concrete

This paper summarises results of a research programme on the applicability of combined non-destructive methods for the estimation of concrete strength. The main objective is to analyse the possibilities and restrictions of a combined ultrasound-rebound hammer method when it is used in the evaluation of concrete, omitting many correction factors that are usually proposed. Ultrasonic pulse velocity, rebound hammer number and concrete compressive strength were correlated applying simple and multiple regression analysis. Several functions were considered, evaluating the confidence of the estimations obtained. In this work, samples are classified considering the type of aggregate used. The uncertainty affecting the estimations of compressive strength obtained by the application of this methodology is quantified.