Evaluation of concrete properties by combining NDT methods

Abstract

The combination of NDT methods is currently considered as one of the more relevant way to improve the quality of the diagnosis of concrete structures. Indeed, many research actions involve the use of several families of NDT methods (ultrasonic, electromagnetic...) for the imaging of structures (voids detection, tendons and reinforcement localisation). Previous studies have shown that this approach is particularly suitable for assessing concrete properties, because concrete is a complex material in which the properties are interacting. For instance mechanical properties depend on moisture which also affects the NDT measurements. On one hand, moisture can be considered as a bias factor which affects the measurement but on the other hand, moisture has also to be considered as a durability indicator, as in such conditions the penetration of aggressive agents and the development of internal reactions is favoured. The combination of NDT methods, some being mainly sensitive to mechanical properties and others being more affected by moisture could be really relevant. Another approach concerns the assessment of chloride content which is also significantly affected by moisture. This paper will describe how the role of NDT methods regarding some concrete properties can be quantified. A specific procedure is also proposed to assess the complementarity of different NDT methods regarding the evaluation of two conjugated properties. © RILEM 2013.