Non-destructive Testing In Civil Engineering Research Articles

Application of iterative elastic reverse time migration to shear horizontal ultrasonic echo data obtained at a concrete step specimen

AbstractThe ultrasonic echo technique is broadly applied in non‐destructive testing (NDT) of concrete structures involving tasks such as measuring thickness, determining geometry and locating built‐in elements. To address the challenge of enhancing ultrasonic imaging for complex concrete constructions, we adapted a seismic imaging algorithm – reverse time migration (RTM) – for NDT in civil engineering. Unlike the traditionally applied synthetic aperture focusing technique (SAFT), RTM takes into account the full wavefield including primary and reflected arrivals as well as multiples. This capability enables RTM to effectively handle all wave phenomena, unlimited by changes in velocity and reflector inclinations. This paper concentrates on applying and evaluating a two‐dimensional elastic RTM algorithm that specifically addresses horizontally polarized shear (SH) waves only, as these are predominantly used in ultrasonic NDT of concrete structures. The elastic SH RTM algorithm was deployed for imaging real ultrasonic echo SH‐wave data obtained at a concrete specimen exhibiting a complex back wall geometry and containing four tendon ducts. As these features are frequently encountered in practical NDT scenarios, their precise imaging holds significant importance. By applying the elastic SH RTM algorithm, we successfully reproduced nearly all reflectors within the concrete specimen. In particular, we were capable of accurately reconstructing all vertically oriented reflectors as well as the circular cross sections of three tendon ducts, which was not achievable with traditional SAFT imaging. These findings demonstrate that elastic SH RTM holds the ability to considerably improve the imaging of complex concrete geometries, marking a crucial advancement for accurate, high‐quality ultrasonic NDT in civil engineering.

Controlled Creating of Delaminations in Concrete for Nondestructive Testing

Locating and sizing delaminations is a common inspection task in the maintenance and quality control of construction and rehabilitation. Their detection is an important area of application of nondestructive testing in civil engineering (NDT-CE). To improve this application, NDT test systems and test solutions must be compared, for which specimens containing well-defined delaminations are needed to serve as a reference. Currently, there are no widely accepted procedures available for creating such flaws locally and reproducibly. This study presents procedures for creating artificial delaminations repeatably and as close as possible to natural delaminations. To produce the discontinuities only substances were used which can occur in concrete components and do not affect the application of NDT-CE methods. Ultrasonic pulse-echo (UPE) was used to test the flaws in the specimens. The delaminations were created by applying expansive mortar in prepared through holes. Three specimens with two delaminations each were built and tested using UPE.

Application of Iterative Elastic SH Reverse Time Migration to Synthetic Ultrasonic Echo Data

The ultrasonic echo technique is widely used in non-destructive testing (NDT) of concrete objects for thickness measurements, geometry determinations and localization of built-in components. To improve ultrasonic imaging of complex concrete structures, we transferred a seismic imaging technique, the Reverse Time Migration (RTM), to NDT in civil engineering. RTM, in contrast to the conventionally used synthetic aperture focusing technique (SAFT) algorithms, considers all wavefield types and thus, can handle complex wave propagations in any direction with no limit on velocity variations and reflector dip. In this paper, we focused on the development, application and evaluation of a two-dimensional elastic RTM algorithm considering horizontally polarized shear (SH) waves only. We applied the elastic SH RTM routine to synthetic ultrasonic echo SH-wave data generated with a concrete model incorporating several steps and circular cavities. As these features can often be found in real-world NDT use cases, their imaging is extremely important. By using elastic SH RTM, we were able to clearly reproduce almost all reflectors inside the concrete model including the vertical step edges and the cross sections of the cavities. We were also capable to show that more features could be mapped compared to SAFT, and that imaging of complex reflectors could be sharpened compared to elastic P-SV (compressional-vertically polarized shear) RTM. Our promising results illustrate that elastic SH RTM has the potential to significantly enhance the reconstruction of challenging concrete structures, representing an important step forward for precise, high-quality ultrasonic NDT in civil engineering.

Non-destructive testing in civil engineering: A memorandum for teaching at German-speaking universities

This contribution summarizes actual developments and draft fundamental teaching topics in the field of non-destructive testing in civil engineering (NDTCE). It is based on the first memorandum on teaching and research in the field of NDTCE at Germanspeaking universities and provides an overview of the academic education and highlights possible focuses, especially in regards to teaching but also takes into account noteworthy developments and topics in research in the field of NDTCE. Suggestions are given for the development and advancement of the teaching curricula in regards to a comprehensive and sound professional education of students in civil engineering and adjacent disciplines. In terms of content and form, this contribution is based on the memorandum of university teachers in the sister field of “Building Materials”. Resulting parallels are therefore not by chance but rather intended. The memorandum was developed out of an initiative of the Subcommittee on Education – Workgroup Education in Universities – of the technical committee NDT in Civil Engineering of the German Society for Nondestructive Testing (DGZfP).

Introduction to DIN 4871: Qualification of NDT Personnel in Civil Engineering (NDT-CE)

Recently, non-destructive testing in civil engineering (NDT-CE), in particular of concrete components, has successfully mastered the leap from research to practice. Several methods have been established for field inspections to determine the concrete cover of reinforcement or to estimate the compressive strength as well as other parameters related to the concrete material. In addition, the application of nondestructive testing is indispensable, if information about the inner structure - such as the location of rebars and tendon ducts or the damage-related condition assessment to detect grouting defects, honeycombs, delamination, or corrosion - is required. Besides the selection of a suitable NDT method and an appropriate inspection system, the reliability of the results depends largely on the person who applies the non-destructive inspection technique and evaluates the inspection results. To ensure a high quality of non-destructive concrete evaluation as well as to keep the uncertainty caused by the inspection personnel to a minimum, structured, consistent and regulated theoretical as well as practical training of inspection personnel is essential. To close this gap, the subcommittee of education (UA-A) within the committee for NDT-CE of the German Society for Nondestructive Testing (DGZfP) has been reactivated in 2018 to establish uniform training standards for nondestructive concrete inspections in the long term. The subcommittee consists of scientists, practitioners, authorities, and clients. So far, the national standard DIN 4871 “Non-destructive testing - Qualification and Certification of NDT personnel in Civil Engineering (NDT-CE)” was developed and is currently under review. This standard considers the civil-industry-specifics, for example, that standards for NDT of concrete, as well as related product standards with a few exceptions, still do not exist at the moment. Within this presentation, the concept, the connection to ISO 9712 and other standards as well as an overview of the developed German standard DIN 4871 will be presented.

Non-Destructive Testing in Civil Engineering

The progressive development of civil engineering has forced scientists to improve the known methods and techniques of testing building materials, and also to search for new ones, e.g., non-destructive testing (NDT) methods [...]

An Ontology-Based Approach to Enable Data-Driven Research in the Field of NDT in Civil Engineering

Although measurement data from the civil engineering sector are an important basis for scientific analyses in the field of non-destructive testing (NDT), there is still no uniform representation of these data. An analysis of data sets across different test objects or test types is therefore associated with a high manual effort. Ontologies and the semantic web are technologies already used in numerous intelligent systems such as material cyberinfrastructures or research databases. This contribution demonstrates the application of these technologies to the case of the 1H nuclear magnetic resonance relaxometry, which is commonly used to characterize water content and porosity distribution in solids. The methodology implemented for this purpose was developed specifically to be applied to materials science (MS) tests. The aim of this paper is to analyze such a methodology from the perspective of data interoperability using ontologies. Three benefits are expected from this approach to the study of the implementation of interoperability in the NDT domain: First, expanding knowledge of how the intrinsic characteristics of the NDT domain determine the application of semantic technologies. Second, to determine which aspects of such an implementation can be improved and in what ways. Finally, the baselines of future research in the field of data integration for NDT are drawn.

Experimental analysis of the acoustic field of an ultrasonic pulse induced by a fluidic switch.

Ultrasonic inspection is a common tool for non-destructive testing in civil engineering (NDT-CE). Currently, transducers are coupled directly to the specimen surface, which makes the inspection time-consuming. Air-coupled ultrasound (ACU) transducers are more time-efficient but need a high pressure amplitude as the impedance mismatch between the air and the concrete is high and large penetration depth is needed for the inspection. Current approaches aim at eliminating the impedance mismatch between the transducer and the air to gain amplitude; however, they hardly fulfill the NDT-CE requirements. In this study, an alternative approach for ultrasound generation is presented: the signal is generated by a fluidic switch that rapidly injects a mass flow into the ambience. The acoustic field, the flow field, and their interaction are investigated. It is shown that the signal has dominant frequencies in the range of 35-60 kHz, and the amplitude is comparable to that of a commercial ACU transducer.

Detection of near-surface reinforcement in concrete components with ultrasound

Ultrasonic testing of concrete has grown in importance considerably in recent years in non-destructive testing in civil engineering (NDT-CE). In the past, the main focus was on the imaging of the internal construction of steel and prestressed concrete components. On the other hand, comparatively little attention was paid to the location of near-surface reinforcement and concrete cover measurement. In this research, it is shown to what extent ultrasound is suitable for the detection of near-surface reinforcement in addition to magnetic inductive methods. The measurements were carried out with the newly developed Pundit 250 Array from the company Proceq and with the measuring devices of the company Acsys, the A1220 Monolith and the A1040 Mira. The ultrasound data was analysed with the vendor-independent software InterSAFT of the University of Kassel. Systematic investigations were carried out on test specimens with a variety on the concrete cover, the diameter of the reinforcement and the reinforcement ratio in the form of mesh reinforcement close to the surface. The detectability and accuracy of the concrete cover were set in relation to the concrete cover, wavelength and reinforcement diameter, with the result that more detailed rules for the detection of reinforcement are formulated for the user, instead of the known λ/2-criterion.

Non-Destructive Testing in Civil Engineering

Preface to Special Collection of coutributions to the International Symposium NDT-CE 2015 in Berlin/ Germany.

Methods to Assess the Quality of Non-Destructive Testing in Civil Engineering Using POD and GUM for Static Calculations of Existing Structures

AbstractTo draw reliable conclusions from results gained with non-destructive testing methods in civil-engineering (NDT-CE) it is important to know about the quality of results. Since recent times, the POD (probability of detection) according to MIL-HDBK-1823A and Berens Report is established in non-destructive testing in civil engineering (NDT-CE) to assess the reliability of qualitative testing problems. For determining the uncertainty of measurements of quantitative (metric) problems the Guide (Guide to the Expression of Uncertainty in Measurements – GUM) is used in NDT-CE. Now, a new approach is to adapt both methods to get statistically secured measurement results with NDT-CE from existing structures such as prestressed bridges. This paper introduces how calculations based on stochastic models can be used together with NDT-CE results analysed with POD and the Guide.

Assessment of Existing Structures using Probabilistic Analysis Methods in Combination with Nondestructive Testing Methods

Increasing daily traffic volume with rising numbers of axles and allowable load per axle demands appropriate load models for structural analysis. Such models have been developed and incorporated according to latest standards. By adopting the new load models, the load-bearing capacity of many in-service structures can be increased. Therefore, a realistic assessment of the structure especially for the existing bridges is needed. Nondestructive testing (NDT) is used to give realistic import values for structural analysis. This article outlines a procedure for combining the results of NDT in civil engineering (NDT-CE) and the stochastic models used for probabilistic analysis to quantify the reliability of a structure given by the reliability index. The idea of implementing the measurement results as statistic variables in stochastic models is not new. This article presents a novel flexible approach to quantify the uncertainty of measurement according to the Guide to the Expression of Uncertainty in Measurement (GUM). The GUM approach allows one to easily update input quantities and quantify their effect on the total uncertainty without repeating the whole process. The reliability of an NDT method can be quantified in advance by conducting carefully designed probability of detection (POD) studies. A case study of an existing bridge is presented here, where it will be shown by means of a sensitivity analysis how detailed knowledge—gained from reliable NDT-CE measurements—of the dead loads or the exact position of tendon ducts can influence the reliability index. Combining reliable NDT-CE measurements and probabilistic analysis allows assessment of the “true” as-built structure with the purpose of proving its stability based on detailed structural and statistical knowledge.

Structural Damage Identification by Detection Medium Technology

There are two conventional techniques i.e. the approach based on structural testing and non-damaged detecting method, of which the former is partial to structural integrity analysis while the latter focuses on partial detection. The damage identification approach is discussed from the perspective of detection medium in the paper. And non-destructive testing in civil engineering (NDT-CE), of which the research status and existing issues are presented, can be attributed into three categories as following: one is based on the stress wave theory, such as impact-echo method, acoustic emission technique and ultrasonic pulse method; one employs the mechanism of electromagnetic wave propagation on behalf of GPR; one uses radiography as the medium, for instance, infrared imaging and computerized tomography. It is emphasized that ground penetrating radar (GPR) has been applied in practice and studied more and more, and moreover, the prospects in the field are provided.

Special Issue on Nondestructive Testing in Civil Engineering

This special issue of the Journal of Infrastructure Systems aims to provide an overview on advances of advanced nondestructive testing (NDT) applied to civil engineering structures. Indeed, a stage has been reached in which a substantial part of the infrastructure is entering a critical age. Dams, bridges, tunnels, pavements, and nuclear power plants require sustainable maintenance to qualify for extension of their service life in good condition and safely with appropriate service level. NDT methods have their places aside more widespread visual inspections and destructive tests within this process even though few standardized procedures exist. Because of their nonintrusive nature, NDT methods will play a prominent role in the future as more and more challenges specific to civil engineering problems, such as very large investigation zones and low cost requirements, have recently started to be tackled by researchers and companies involved in this field (automation, imaging, optimized data acquisition procedures, signal processing, and miniaturization of the equipment). Today, a wide range of NDT methods are available, including electromagnetic methods, ultrasonic methods, electrical methods, optical methods, eddy current, infrared thermography, and gammagraphy. A combination of several methods is often judicious taking into account that, on the one hand, the structures surveyed are often complex and in an open varying environment and that, on the other hand, NDT observables are usually not in direct link with engineering information needs (porosity, density, residual stress, and bounding). NDT development is ineluctable but should rely on an improved understanding of its underlying physical principles. Also, standards, education, and training need to be addressed. Nondestructive evaluation also concerns structural health monitoring with the design of cost efficient permanent instrumentations to survey modifications over time and space, not to mention the use of NDT data as input and output controls for residual time life prediction models. Because of previous international symposia on NDT in civil engineering, the interest in such techniques has grown, induced by an increase in their confidence, reliability, and user-friendliness. Nevertheless, some elements have to be improved, including their cost effectiveness through high acquisition rates, and the knowledge of the links between ND measurements and the durability indicators of the surveyed structures. Thus, the following papers highlight some particular results presented during the International Symposium on NDT in Civil Engineering (NDTCE’09), coorganized in Nantes, France, by IFSTTAR (former LCPC), the Research Institute in Civil and Mechanical Engineering (UMR CNRS GeM—Nantes Univ.) and COFREND (the French Association for Nondestructive Testing). The first paper by Kruschwitz et al. is on the application of spectral induced polarization (SIP), a well-known test method in geophysics on flooded masonry. Gucunski et al. propose a three-dimensional approach by using the Impact-Echo technique to survey a bridge deck. The associated interpretation methodology allows both the overall assessment of the condition of the deck and the identification of deteriorated zones of the deck for repair or rehabilitation. In the next paper, Felicetti tends to limit the destructive approach by using the analysis of cores for the assessment of deteriorated cover-concretes, although, taking into account the information from drilling monitoring. Then a small hole realized by a hammer-drilling method gives faster and reliable information of the variability of the mechanical properties versus depth. The fourth paper (Arosio et al.) deals with radar and sonic NDT techniques used for the quality control of concrete masonries. For that, an automatic specific procedure has been designed, and it tested as well on laboratory test structures as on-site. The last paper (Pinto et al.) is devoted to the determination of load-deflection curves of as-built drilled shafts of a case study. The testing program consisted of monitoring accelerations generated at the top of the shaft by means of a dynamic-force transducer. A numerical approach has been developed to extrapolate the load-deflection curve into the service load range, thus defining load-deflection curves.

Special issue on nondestructive testing in civil engineering

Special issue on nondestructive testing in civil engineering

Special issue on Nondestructive Testing in Civil Engineering

Special issue on Nondestructive Testing in Civil Engineering

Non‐Destructive Testing in Civil Engineering (NDT‐CE)

BautechnikVolume 79, Issue 5 p. 344-344 Termine Non-Destructive Testing in Civil Engineering (NDT-CE) First published: 28 March 2013 https://doi.org/10.1002/bate.200202410AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume79, Issue5May 2002Pages 344-344 RelatedInformation

Non‐Destructive Testing in Civil Engineering (NDT‐CE)

Non‐Destructive Testing in Civil Engineering (NDT‐CE)

Improvement of ultrasonic testing of concrete by combining signal conditioning methods, scanning laser vibrometer and space averaging techniques

This paper deals with the combination of several techniques to improve the ultrasonic pulse echo testing of concrete elements when a laser doppler interferometer is used as the ultrasonic receiver. This techniques involves specially designed ultrasonic probes, a pulse compression technique, random speckle modulation and space time signal processing methods. The pulse echo technique is carried out by sending frequency modulated chirp signals and performing a cross-correlation between the received and the transmitted signals. In combination with the application of recently available ultrasonic concrete probes as transmitter, this leads to an improvement in the signal-to-noise ratio. A laser doppler interferometer, equipped with a random speckle modulator, is used as detector of the ultrasound. Finally, the data sets are processed with various methods, involving time signals of several space points. Examples are the space averaging and the synthetic aperture focusing technique (SAFT). The advantage of the suggested technique is demonstrated by practical measurements on a test specimen. The improvement in results as compared to standard laser interferometric measurements will increase the feasibility of laser interferometric detection for non-destructive testing in civil engineering.

Ultrasonic pulse method for detecting internal defects and cracks in concrete structures : 52152 Luo, Q. Non-Destructive Testing in Civil Engineering, Liverpool (United Kingdom), 14–16 Apr. 1993. Vol. 2, pp. 531–550. Edited by J.H. Bungey. The British Institute of NDT (1993)

The ultrasonic pulse method has been used for many years for the detection of internal defects in concrete structures. There are, however, only quantitative differences between the acoustic parameters (pulse velocity, amplitude of the wave) of regions containing defects and those without defects when using transmission measurements. Methods of judgment whether internal defects exist or not based on the data obtained from the different measuring points thus becomes a worthwhile topic to explore. The Author has proposed a method based on the theory of mathematical statistics - the Probability Method. This method has been verified to be valid through practice. The shortcomings of empiricism in judging defects have been eliminated by using this method and automation in judgment and analysis work is also possible. Cracks are often found in concrete structures for a variety of reasons. For shallow cracks, the crack depths can be measured by general ultrasonic pulse methods. For deep cracks with depths more than several metres, the Author has developed an opposite drilling measurement technique to measure their depths. This is based on determining the existence of the cracks through the amplitude changes of the received wave. After the cracks are grouted, the method has also been used to investigate the grouting effectiveness. (A) For the covering abstract see IRRD 861706.