Concrete Quality Designation based on Ultrasonic Pulse Velocity

Evaluating the condition of the original concrete of large structures built in the early twentieth century is an important part of safety review programs. However, in most large concrete structures, rehabilitation works have been carried out over the years, and only a limited number of cases have been well documented with regards to what has been done. Also, in most cases, the original concrete can be hidden under new layers of repair material and remains inaccessible for a proper assessment. In situ Ultrasonic Pulse Velocity (UPV) measurements can be indicative of the level of damage in the original concrete. However, UPV is influenced by the concrete mixture characteristics, which can lead to ambiguous interpretation of the results. The purpose of the Concrete Quality Designation (CQD) proposed in this paper is to determine the degree of damage in concrete relative to its original and undamaged condition. This CQD is based on a comparison between in situ and laboratory UPVs and is corrected with respect to the characteristics of the investigated concrete mixtures. We present a case study where the CQD approach was performed on a hydraulic structure. The results showed that CQD is an accurate method and is sensitive enough to very low and very high degrees of damage. (C) 2016 Elsevier Ltd. All rights reserved.