Application of the German Standardization Approach for the Reliability Assessment of NDT – Honeycomb Detection in Concrete using Ultrasonic Testing

Abstract

In recent decades, non-destructive testing (NDT) has become an indispensable component of condition assessment in various industries such as civil infrastructure, automotive, nuclear, and other safety-related sectors. Each NDT method possesses unique strengths and weaknesses, prompting increased interest in combining these methods for comprehensive assessments. However, the full potential of NDT data remains underutilized due to a lack of standardization in estimating NDT reliability. Often, the capabilities of NDT systems for specific inspection tasks are unknown, hindering advancements in NDE 4.0, where knowledge about the reliability of non-destructive tests is crucial. For example, such information is very valuable when labeling data for machine learning purposes to define whether a measurement can be considered sound or defect. This paper underscores the pressing need for international standardization in the reliability assessment of NDT and presents the German approach. This standard outlines procedures for NDT evaluation, including (i) defining the application, (ii) developing and producing test specimens, (iii) statistically evaluating test results (iv) considering human factors, and more. By doing so, the standard ensures the comparability of reliability assessments and enhances their overall acceptance. This study specifically delves into the discussion of reliability evaluation using a model-based approach for ultrasonic inspection of concrete structures, both with and without reinforcement, and under different defect conditions. In this case, honeycombs are chosen as the investigated defect type. Furthermore, an initial case study applies a Probability of Detection (POD) analysis for ultrasonic testing (UT) data obtained from a concrete specimen with artificial defects. This study represents a pioneering effort for UT in the context of concrete structures.