Relevance of the ultrasonic pulse velocity test for strength assessment of high strength concretes

Abstract

The present paper addresses the ultrasonic pulse velocity (UPV) as a non-destructive testing device for assessing the compressive strength of high strength concrete using a UPV-strength correlation model. UPV-strength correlation models are developed and used for normal strength concrete assessment; however, questions are raised as to the sensitivity of the ultrasonic pulse velocity test when applied for the strength assessment of denser, higher strength concretes. This study is an appraisal of the relevance of this non-destructive testing device for the high performances concrete strength assessment, aiming for a better knowledge of the applicability of this method as a way to improve the on-site non-destructive strength assessment of the high strength concrete. In the study, a high strength concrete within a specified strength range was targeted. Cylindrical concrete specimens were fabricated, left to harden then subjected to UPV and compressive tests so that a correlation model could be built. The developed model was then used to estimate the strength of a second high strength concrete made with the same type of aggregates. The estimated strength was compared to the real strength of this second HPC in order to assess the reliability of the developed model and hence of the ultrasonic pulse velocity testing. At a second stage, the proposed model was compared to the existing models for high strength concrete assessment, as a procedure to consolidate or negate the observations made in the first part. The results highlight the lack of sensitivity of the UPV method used for the assessment of high strength concrete. Indeed, each high strength concrete considered in this study, including those taken from the literature, varies within a particular strength range while the UPV measurements for all the high strength concretes considered vary narrowly within approximately the same range. This reveals that the UPV nondestructive testing method may not be fully reliable in estimating correctly the strength of a high strength concrete within a range different from that on which the model was built.