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Non-destructive Testing in Civil Engineering
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Non-destructive Testing in Civil Engineering

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Civil Engineering".

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 46723

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Jerzy Hoła

E-Mail Website
Guest Editor
Department of Building Engineering, Wrocław University of Science and Technology, 50-370 Wrocław, Poland
Interests: construction; building materials; cement composites; brick walls; dampness; non-destructive testing methods; artificial intelligence
Prof. Dr. Łukasz Sadowski

E-Mail Website
Guest Editor
Department of Building Engineering, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wrocław, Poland
Interests: cementitious materials; sustainable development; artificial intelligence; nondestructive testing; surface morphology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The progressive development of civil engineering involves the development of already known methods and the search for new techniques for testing materials, elements, structures, and entire buildings. In these activities, much attention is focused on non-destructive testing (NDT) methods, which, in principle, do not interfere with the structures being tested. However, they allow many important features and parameters to be assessed as well as imperfections, damage, or internal defects to be located. Such knowledge is needed in many situations, i.e., for structures and buildings for the correct assessment of the degree of degradation, safety of use, reliability, or durability. Significant progress has recently occurred in the development of the acoustic group of methods, where, as in medicine, the trend is obtaining information about examined structures and the interior of elements from acoustic signals processed by appropriate software using complex data analysis, including artificial intelligence.

This Special Issue aims to present to all those interested  in the cognition and application of non-destructive testing, the latest achievements and experience regarding new research methods and their applications, the effects of the latest original scientific research, and the effects of utilitarian, laboratory, and field applications conducted in the area of civil engineering.

We invite you to send original articles on topics including but not limited to:

- new and improved non-destructive testing methods and techniques;

- complementary applications of research methods;

- original research methodologies;

- analysis of non-destructive test results, including the use of sophisticated mathematical algorithms and artificial intelligence;

- diagnostics of materials, elements, and structures, as well as entire buildings; and

 - unusual case studies in the field of non-destructive testing in civil engineering.

Prof. Jerzy Hoła
Prof. Łukasz Sadowski
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • non-destructive testing
  • civil engineering
  • construction materials
  • structures
  • buildings

Published Papers (18 papers)

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Editorial

Jump to: Research, Review

6 pages, 210 KiB  
Editorial
Non-Destructive Testing in Civil Engineering
by Jerzy Hoła and Łukasz Sadowski
Appl. Sci. 2022, 12(14), 7187; https://0-doi-org.brum.beds.ac.uk/10.3390/app12147187 - 17 Jul 2022
Cited by 3 | Viewed by 2411
Abstract
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 [...] Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)

Research

Jump to: Editorial, Review

17 pages, 3288 KiB  
Article
Force Measurement with a Strain Gauge Subjected to Pure Bending in the Fluid–Wall Interaction of Open Water Channels
by Luis Santana, Diego Rivera and Eric Forcael
Appl. Sci. 2022, 12(3), 1744; https://0-doi-org.brum.beds.ac.uk/10.3390/app12031744 - 08 Feb 2022
Cited by 2 | Viewed by 2482
Abstract
An experimental method to measure forces of small magnitude with a strain gauge as a force sensor in the fluid–wall interaction of open water channels is presented. Six uniaxial strain gauges were employed for this purpose, which were embedded across the entire sensing [...] Read more.
An experimental method to measure forces of small magnitude with a strain gauge as a force sensor in the fluid–wall interaction of open water channels is presented. Six uniaxial strain gauges were employed for this purpose, which were embedded across the entire sensing area and subjected to pure bending, employing two-point bending tests. Sixteen two-point bending tests were performed to determine the existence of a direct relationship between the load and the instrument signal. Furthermore, a regression analysis was used to estimate the parameters of the model. A data acquisition system was developed to register the behavior of the strain gauge relative to the lateral displacement induced by the loading nose of the universal testing machine. The results showed a significant linear relationship between the load and the instrumental signal, provided that the strain gauge was embedded between 30% and 45% of the central axis in the sensing area of the sensor (R2 > 0.99). Thus, the proposed sensor can be employed to measure forces of small magnitude. Additionally, the linear relationship between the load and the instrumental signal can be used as a calibration equation, provided that the strain gauge is embedded close to the central axis of the sensing area. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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14 pages, 8404 KiB  
Article
Non-Destructive Multi-Method Assessment of Steel Fiber Orientation in Concrete
by Sabine Kruschwitz, Tyler Oesch, Frank Mielentz, Dietmar Meinel and Panagiotis Spyridis
Appl. Sci. 2022, 12(2), 697; https://0-doi-org.brum.beds.ac.uk/10.3390/app12020697 - 11 Jan 2022
Cited by 5 | Viewed by 1625
Abstract
Integration of fiber reinforcement in high-performance cementitious materials has become widely applied in many fields of construction. One of the most investigated advantages of steel fiber reinforced concrete (SFRC) is the deceleration of crack growth and hence its improved sustainability. Additional benefits are [...] Read more.
Integration of fiber reinforcement in high-performance cementitious materials has become widely applied in many fields of construction. One of the most investigated advantages of steel fiber reinforced concrete (SFRC) is the deceleration of crack growth and hence its improved sustainability. Additional benefits are associated with its structural properties, as fibers can significantly increase the ductility and the tensile strength of concrete. In some applications it is even possible to entirely replace the conventional reinforcement, leading to significant logistical and environmental benefits. Fiber reinforcement can, however, have critical disadvantages and even hinder the performance of concrete, since it can induce an anisotropic material behavior of the mixture if the fibers are not appropriately oriented. For a safe use of SFRC in the future, reliable non-destructive testing (NDT) methods need to be identified to assess the fibers’ orientation in hardened concrete. In this study, ultrasonic material testing, electrical impedance testing, and X-ray computed tomography have been investigated for this purpose using specially produced samples with biased or random fiber orientations. We demonstrate the capabilities of each of these NDT techniques for fiber orientation measurements and draw conclusions based on these results about the most promising areas for future research and development. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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9 pages, 1485 KiB  
Communication
The Sonic Resonance Method and the Impulse Excitation Technique: A Comparison Study
by Tomáš Húlan, Filip Obert, Ján Ondruška, Igor Štubňa and Anton Trník
Appl. Sci. 2021, 11(22), 10802; https://0-doi-org.brum.beds.ac.uk/10.3390/app112210802 - 16 Nov 2021
Cited by 3 | Viewed by 2422
Abstract
In this study, resonant frequencies of flexurally vibrating samples were measured using the sonic resonant method (SRM) and the impulse excitation technique (IET) to assess the equivalency of these two methods. Samples were made from different materials and with two shapes (prism with [...] Read more.
In this study, resonant frequencies of flexurally vibrating samples were measured using the sonic resonant method (SRM) and the impulse excitation technique (IET) to assess the equivalency of these two methods. Samples were made from different materials and with two shapes (prism with rectangular cross-section and cylinder with circular cross-section). The mean values and standard deviations of the resonant frequencies were compared using the t-test and the F-test. The tests showed an equivalency of both methods in measuring resonant frequency. The differences between the values measured using SRM and IET were not significant. Graphically, the relationship between the resonant frequencies is a line with a slope of 0.9993 ≈ 1. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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23 pages, 8688 KiB  
Article
Analysis of Fine Crack Images Using Image Processing Technique and High-Resolution Camera
by Hoseong Jeong, Baekeun Jeong, Myounghee Han and Dooyong Cho
Appl. Sci. 2021, 11(20), 9714; https://0-doi-org.brum.beds.ac.uk/10.3390/app11209714 - 18 Oct 2021
Cited by 4 | Viewed by 1995
Abstract
Visual inspections are performed to investigate cracks in concrete infrastructure. These activities require manpower or equipment such as articulated ladders. Additionally, there are health and safety issues because some structures have low accessibility. To deal with these problems, crack measurement with digital images [...] Read more.
Visual inspections are performed to investigate cracks in concrete infrastructure. These activities require manpower or equipment such as articulated ladders. Additionally, there are health and safety issues because some structures have low accessibility. To deal with these problems, crack measurement with digital images and digital image processing (DIP) techniques have been adopted in various studies. The objective of this experimental study is to evaluate the optical limit of digital camera lenses as working distance increases. Three different lenses and two digital cameras were used to capture images of lines ranging from 0.1 to 0.5 mm in thickness. As a result of the experiments, it was found that many elements affect width measurement. However, crack width measurement is dependent on the measured pixel values. To accurately measure width, the measured pixel values must be in decimal units, but that is theoretically impossible. According to the results, in the case of 0.3 mm wide or wider cracks, a working distance of 1 m was secured when the focal length was 50 mm, and working distances of 3 m and 4 m were secured when the focal length was 100 mm and 135 mm, respectively. However, for cracks not wider than 0.1 mm, focal lengths of 100 mm and 135 mm showed measurability within 1 m, but a focal length of 50 mm was judged to hardly enable measurement except for certain working positions. Field measurement tests were conducted to verify measurement parameters identified by the results of the indoor experiment. The widths of actual cracks were measured through visual inspection and used for the analysis. From the evaluation, it was confirmed that the number of pixels corresponding to the working distance had a great influence on crack width measurement accuracy when using image processing. Therefore, the optimal distance and measurement guidelines required for the measurement of the size of certain objects was presented for the imaging equipment and optical equipment applied in this study. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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16 pages, 3113 KiB  
Article
Combining Signal Features of Ground-Penetrating Radar to Classify Moisture Damage in Layered Building Floors
by Tim Klewe, Christoph Strangfeld, Tobias Ritzer and Sabine Kruschwitz
Appl. Sci. 2021, 11(19), 8820; https://0-doi-org.brum.beds.ac.uk/10.3390/app11198820 - 23 Sep 2021
Cited by 3 | Viewed by 1656
Abstract
To date, the destructive extraction and analysis of drilling cores is the main possibility to obtain depth information about damaging water ingress in building floors. The time- and cost-intensive procedure constitutes an additional burden for building insurances that already list piped water damage [...] Read more.
To date, the destructive extraction and analysis of drilling cores is the main possibility to obtain depth information about damaging water ingress in building floors. The time- and cost-intensive procedure constitutes an additional burden for building insurances that already list piped water damage as their largest item. With its high sensitivity for water, a ground-penetrating radar (GPR) could provide important support to approach this problem in a non-destructive way. In this research, we study the influence of moisture damage on GPR signals at different floor constructions. For this purpose, a modular specimen with interchangeable layers is developed to vary the screed and insulation material, as well as the respective layer thickness. The obtained data set is then used to investigate suitable signal features to classify three scenarios: dry, damaged insulation, and damaged screed. It was found that analyzing statistical distributions of A-scan features inside one B-scan allows for accurate classification on unknown floor constructions. Combining the features with multivariate data analysis and machine learning was the key to achieve satisfying results. The developed method provides a basis for upcoming validations on real damage cases. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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12 pages, 6569 KiB  
Article
Estimating Thermal Material Properties Using Step-Heating Thermography Methods in a Solar Loading Thermography Setup
by Samuel Klein, Tobias Heib and Hans-Georg Herrmann
Appl. Sci. 2021, 11(16), 7456; https://0-doi-org.brum.beds.ac.uk/10.3390/app11167456 - 13 Aug 2021
Cited by 4 | Viewed by 1221
Abstract
This work investigates solar loading thermography applications using active thermography algorithms. It is shown that active thermography methods, such as step-heating thermography, present good correlation with a solar loading setup. Solar loading thermography is an approach that has recently gained scientific attention and [...] Read more.
This work investigates solar loading thermography applications using active thermography algorithms. It is shown that active thermography methods, such as step-heating thermography, present good correlation with a solar loading setup. Solar loading thermography is an approach that has recently gained scientific attention and is advantageous because it is particularly easy to set up and can measure large-scale objects, as the sun is the primary heat source. This work also introduces the concept of using a pyranometer as a reference for the evaluation algorithms by providing a direct solar irradiance measurement. Furthermore, a recently introduced method of estimating thermal effusivity is evaluated on ambient-derived thermograms. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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26 pages, 15884 KiB  
Article
Quantitative Evaluation of Unfilled Grout in Tendons of Prestressed Concrete Girder Bridges by Portable 950 keV/3.95 MeV X-ray Sources
by Mitsuru Uesaka, Jian Yang, Katsuhiro Dobashi, Joichi Kusano, Yuki Mitsuya and Yoshiyuki Iizuka
Appl. Sci. 2021, 11(12), 5525; https://0-doi-org.brum.beds.ac.uk/10.3390/app11125525 - 15 Jun 2021
Cited by 2 | Viewed by 1781
Abstract
We have developed porTable 950 keV/3.95 MeV X-band (9.3 GHz) electron linear accelerator (LINAC)-based X-ray sources and conducted onsite prestressed concrete (PC) bridge inspection in the last 10 years. A T-shaped PC girder bridge with a thickness of 200–400 mm and a box-shaped [...] Read more.
We have developed porTable 950 keV/3.95 MeV X-band (9.3 GHz) electron linear accelerator (LINAC)-based X-ray sources and conducted onsite prestressed concrete (PC) bridge inspection in the last 10 years. A T-shaped PC girder bridge with a thickness of 200–400 mm and a box-shaped PC girder bridge with a thickness of 200–800 mm were tested. X-ray transmission images of flaws such as thinning, fray, and disconnection caused by corrosion of PC wires and unfilled grout were observed. A three-dimensional structural analysis was performed to estimate the reduction in the yield stress of the bridge. In this study, we attempted to evaluate the unfilled grout quantitatively because it is the main flaw that results in water filling and corrosion. In the measured X-ray images, we obtained gray values, which correspond to the X-ray attenuation coefficients of filled/unfilled grouts, PC wires (steel) in a sheath, and concrete. Then, we compared the ratio of the gray values of the filled/unfilled grouts and PC wires to determine the stage of the unfilled grout. We examined this quantitative evaluation using the data obtained from a real T-shaped PC girder bridge and model samples to simulate thick box-shaped PC girder bridges. We obtained a clear quantitative difference in the ratios for unfilled and filled grouts, which coincided with our visual perception. We synthesized the experience and data and proposed a quantitative analysis for evaluating the unfilled grout for subsequent steps such as structural analysis and destructive evaluation by boring surveys. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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13 pages, 6166 KiB  
Article
Estimating Thermal Material Properties Using Solar Loading Lock-in Thermography
by Samuel Klein, Henrique Fernandes and Hans-Georg Herrmann
Appl. Sci. 2021, 11(7), 3097; https://0-doi-org.brum.beds.ac.uk/10.3390/app11073097 - 31 Mar 2021
Cited by 2 | Viewed by 1674
Abstract
This work investigates the application of lock-in thermography approach for solar loading thermography applications. In conventional lock-in thermography, a specimen is subjected to a periodically changing heat flux. This heat flux usually enters the specimen in one of three ways: by a point [...] Read more.
This work investigates the application of lock-in thermography approach for solar loading thermography applications. In conventional lock-in thermography, a specimen is subjected to a periodically changing heat flux. This heat flux usually enters the specimen in one of three ways: by a point source, a line source or an extended source (area source). Calculations based on area sources are particularly well suited to adapt to solar loading thermography, because most natural heat sources and heat sinks can be approximated to be homogenously extended over a certain region of interest. This is of particular interest because natural heat phenomena cover a large area, which makes this method suitable for measuring large-scale samples. This work investigates how the extended source approximation formulas for determining thermally thick and thermally thin material properties can be used in a naturally excited setup, shows possible error sources, and gives quantitative results for estimating thermal effusivity of a retaining wall structure. It shows that this method can be used on large-scale structures that are subject to natural outside heating phenomena. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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14 pages, 2408 KiB  
Article
Influence of HFM Thermal Contact on the Accuracy of In Situ Measurements of Façades’ U-Value in Operational Stage
by Katia Gaspar, Miquel Casals and Marta Gangolells
Appl. Sci. 2021, 11(3), 979; https://0-doi-org.brum.beds.ac.uk/10.3390/app11030979 - 22 Jan 2021
Cited by 11 | Viewed by 2419
Abstract
Accurate information on the actual thermal transmittance of walls is vital to select appropriate energy-saving measures in existing buildings to meet the commitments of the European Green Deal. To obtain accurate results using the heat flow meter (HFM) method, good thermal contact must [...] Read more.
Accurate information on the actual thermal transmittance of walls is vital to select appropriate energy-saving measures in existing buildings to meet the commitments of the European Green Deal. To obtain accurate results using the heat flow meter (HFM) method, good thermal contact must be made between the heat flow meter plate and the wall surface. This paper aimed to assess the influence of the non-perfect thermal contact of heat flow meter plates on the accuracy of in situ measurement of the façades’ U-value when a film was applied to avoid damage to the wall surface. Given the fact that to avoid harm to the wall surface, the laying of a film is a usual procedure in the installation of equipment during the building’s operational stage. The findings show that deviations between measured U-values when an HFM was installed directly on the wall surface and when an HFM was installed with a PVC film were found to differ significantly from the theoretical effect of including a PVC film during the monitoring process. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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10 pages, 1900 KiB  
Article
Longitudinal Monostatic Acoustic Effective Bulk Modulus and Effective Density Evaluation of Underground Soil Quality: A Numerical Approach
by Yuqi Jin, Tae-Youl Choi and Arup Neogi
Appl. Sci. 2021, 11(1), 146; https://0-doi-org.brum.beds.ac.uk/10.3390/app11010146 - 25 Dec 2020
Cited by 2 | Viewed by 1573
Abstract
In this study, we introduce a novel method using longitudinal sound to detect underground soil voids to inspect underwater bed property in terms of effective bulk modulus and effective density of the material properties. The model was simulated in terms of layered material [...] Read more.
In this study, we introduce a novel method using longitudinal sound to detect underground soil voids to inspect underwater bed property in terms of effective bulk modulus and effective density of the material properties. The model was simulated in terms of layered material within a monostatic detection configuration. The numerical model demonstrates the feasibility of detecting an underground air void with a spatial resolution of about 0.5 λ and can differentiate a soil firmness of about 5%. The proposed technique can overcome limitations imposed by conventional techniques that use spacing-consuming sonar devices and suffer from low penetration depth and leakage of the transverse sound wave propagating in an underground fluid environment. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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20 pages, 3317 KiB  
Article
Analysis of the Applicability of Non-Destructive Techniques to Determine In Situ Thermal Transmittance in Passive House Façades
by Blanca Tejedor, Kàtia Gaspar, Miquel Casals and Marta Gangolells
Appl. Sci. 2020, 10(23), 8337; https://0-doi-org.brum.beds.ac.uk/10.3390/app10238337 - 24 Nov 2020
Cited by 12 | Viewed by 1996
Abstract
Within the European framework, the passive house has become an essential constructive solution in terms of building efficiency and CO2 reduction. However, the main approaches have been focused on post-occupancy surveys, measurements of actual energy consumption, life-cycle analyses in dynamic conditions, using [...] Read more.
Within the European framework, the passive house has become an essential constructive solution in terms of building efficiency and CO2 reduction. However, the main approaches have been focused on post-occupancy surveys, measurements of actual energy consumption, life-cycle analyses in dynamic conditions, using simulation, and the estimation of the thermal comfort. Few studies have assessed the in situ performance of the building fabric of passive houses. Hence, this paper explores the applicability of non-destructive techniques—heat flux meter (HFM) and quantitative infrared thermography (QIRT)—for assessing the gap between the predicted and actual thermal transmittance of passive house façades under steady-state conditions in the Mediterranean climate. Firstly, the suitability of in situ non-destructive techniques was checked in an experimental mock-up, and, subsequently, a detached house was tested in the real built environment. The findings revealed that both Non-Destructive Testing (NDT) techniques allow for the quantification of the gap between the design and the actual façades U-value of a new passive house before its operational stage. QIRT was faster than the HFM technique, although the latter was more accurate. The results will help practitioners to choose the most appropriate method based on environmental conditions, execution of the method, and data analysis. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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11 pages, 3407 KiB  
Article
Verification of a Nondestructive Method for Assessing the Humidity of Saline Brick Walls in Historical Buildings
by Anna Hoła and Łukasz Sadowski
Appl. Sci. 2020, 10(19), 6926; https://0-doi-org.brum.beds.ac.uk/10.3390/app10196926 - 02 Oct 2020
Cited by 5 | Viewed by 2009
Abstract
The paper presents the results of the verification of the neural method for assessing the humidity of saline brick walls. The method was previously developed by the authors and can be useful for the nondestructive assessment of the humidity of walls in historic [...] Read more.
The paper presents the results of the verification of the neural method for assessing the humidity of saline brick walls. The method was previously developed by the authors and can be useful for the nondestructive assessment of the humidity of walls in historic buildings when destructive intervention during testing is not possible due to conservation restrictions. However, before being implemented in construction practice, this method requires validation by verification on other historic buildings, which to date has not been done. The paper presents the results of such verification, which has never been carried out before, and thus extends the scope of knowledge related to the issue. For experimental verification of the artificial neural network (ANN), the results of moisture tests of two selected historic buildings, other than those used for ANN learning and testing processes, were used. An artificial unidirectional multilayer neural network with backward error propagation and the algorithm for learning conjugate gradient (CG) was found to be useful for this purpose. The obtained satisfactory value of the linear correlation coefficient R of 0.807 and low average absolute error |Δf| of 1.16% confirms this statement. The values of average relative error |RE| of 19.02%, which were obtained in this research, were not very high for an in-situ study. Moreover, the relative error values |RE| were mostly in the range of 15% to 25%. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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21 pages, 3910 KiB  
Article
Atlas of Defects within a Global Building Inspection System
by Clara Pereira, Jorge de Brito, José D. Silvestre and Inês Flores-Colen
Appl. Sci. 2020, 10(17), 5879; https://0-doi-org.brum.beds.ac.uk/10.3390/app10175879 - 25 Aug 2020
Cited by 5 | Viewed by 2718
Abstract
Building inspection systems are essential to optimise building maintenance. In the context of developing a global building inspection system, the lack of an expeditious tool to identify defects and their urgency of repair was detected. This study intends to propose an atlas of [...] Read more.
Building inspection systems are essential to optimise building maintenance. In the context of developing a global building inspection system, the lack of an expeditious tool to identify defects and their urgency of repair was detected. This study intends to propose an atlas of defects applicable to several types of building elements/materials, simplifying issues associated with the diagnosis of building pathology. A database was devised using previously developed components of the global inspection system: the classification list of defects and the urgency of repair parameters. Such a database was structured using several pages, each one with tables organised according to types of defects, building elements/materials and levels of urgency of repair (five-level scale—0–4). The atlas of defects has 38 pages in total, each for a different type of defect. The levels of urgency of repair are illustrated with photographs and described with concise classification criteria. Not all levels of urgency of repair apply to all defect–building element/material combinations; levels 1, 2 and 3 are those most often considered. The proposed atlas of defects is an innovative approach, useful to assist surveyors during technical inspections of buildings, whose concept may be adapted to other inspection systems. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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12 pages, 4397 KiB  
Article
Application of Tooth Gear Impact-Echo System for Repeated and Rapid Data Acquisition
by Jinyoung Hong, Hajin Choi and Tae Keun Oh
Appl. Sci. 2020, 10(14), 4784; https://0-doi-org.brum.beds.ac.uk/10.3390/app10144784 - 12 Jul 2020
Cited by 3 | Viewed by 2313
Abstract
Developments in air-coupled testing hardware in impact-echo (IE) tests have enabled new levels of scanning tests for concrete bridge decks. A tooth gear IE system has been developed using tooth gears as impactors and microelectromechanical systems (MEMS). Since the tooth gear moves and [...] Read more.
Developments in air-coupled testing hardware in impact-echo (IE) tests have enabled new levels of scanning tests for concrete bridge decks. A tooth gear IE system has been developed using tooth gears as impactors and microelectromechanical systems (MEMS). Since the tooth gear moves and generates impacts itself, this system collects a large amount of test data across the field continuously. The contact duration of two different tooth gears is evaluated and the contact mechanism is compared to a conventional steel ball impactor by a high-speed camera. The data measurements were carried out on concrete slabs, where artificial delaminations were embedded at different depths. Based on our IE experiments, reducing the pitch or increasing the number of teeth was required to decrease the contact duration and generate the thickness mode frequency from deep delaminations. Rapidly obtained time domain data were transferred to the frequency-time domain using spectrograms to identify the dominant frequency band of the signal set. The results show that the developed system enabled us to acquire high-quality data during air-coupled IE tests and spectrogram analysis provided meaningful frequency information and verified its repeatability. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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20 pages, 12892 KiB  
Article
Non-Destructive Techniques for Building Evaluation in Urban Areas: The Case Study of the Redesigning Project of Eleftheria Square (Nicosia, Cyprus)
by Marilena Cozzolino, Vincenzo Gentile, Paolo Mauriello and Agni Peditrou
Appl. Sci. 2020, 10(12), 4296; https://0-doi-org.brum.beds.ac.uk/10.3390/app10124296 - 23 Jun 2020
Cited by 9 | Viewed by 3550
Abstract
This paper deals with the application of non-destructive geophysical techniques of investigation in the urban environment of the city of Nicosia (Cyprus). The main aim of the research was, in the frame of the Eleftheria Square redesign project, to image subsurface properties in [...] Read more.
This paper deals with the application of non-destructive geophysical techniques of investigation in the urban environment of the city of Nicosia (Cyprus). The main aim of the research was, in the frame of the Eleftheria Square redesign project, to image subsurface properties in order to reduce the impact of hazards on the old buildings (therefore preserving the cultural heritage of the place), and on the new infrastructure under construction. Since 2008, electrical resistivity tomography (ERT), ground penetrating radar (GPR) and induced electromagnetic method (EMI) were employed during the different phases of the project to provide an understanding of geological stratigraphy, the detection of buried objects (archaeological structures and underground utilities) and the solution of unexpected events (such as water infiltration in the course of works). The geophysical results proved the efficiency of the adopted methods, adding scientific value to the knowledge of the studied area. The new gathered information helped the public administration technicians to plan direct and targeted interventions and to modify the original design of the project according to the discovery of archaeological findings. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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17 pages, 8877 KiB  
Article
Investigation of the Effect of Operational Factors on Conveyor Belt Mechanical Properties
by Anna Rudawska, Radovan Madleňák, Lucia Madleňáková and Paweł Droździel
Appl. Sci. 2020, 10(12), 4201; https://0-doi-org.brum.beds.ac.uk/10.3390/app10124201 - 19 Jun 2020
Cited by 13 | Viewed by 2555
Abstract
This paper aims to present the effect of specific operational factors (temperature and humidity) on the selected mechanical properties of a conveyor belt. The tests were conducted in a climatic chamber, simulating the effect of both minus and plus temperatures −30 °C to [...] Read more.
This paper aims to present the effect of specific operational factors (temperature and humidity) on the selected mechanical properties of a conveyor belt. The tests were conducted in a climatic chamber, simulating the effect of both minus and plus temperatures −30 °C to 80 °C (243 K to 353 K) at specific humidity, and in a thermal shock chamber where a varying number of ageing cycles was applied for a specific range of thermal shocks. Six different tests in the climatic chamber and four different tests in a thermal shock chamber were conducted. The results of the climatic chamber tests demonstrate that many strength parameters have undesired values at a temperature of 10 °C (283 K) and 80 °C (353 K) at a relative humidity of 80%. Interestingly, the results revealed that tensile strength, tensile modulus and yield strength are higher at below 0 °C temperature than at above 0 °C temperature. For example, comparing the temperature −30 °C (243 K) and +30 °C (303 K) obtained a difference of tensile modulus of nearly 10%, and comparing the temperature −30 °C (243 K) and +10 °C (283 K) the differences were 22%. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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Review

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42 pages, 1248 KiB  
Review
Electrical Resistivity and Electrical Impedance Measurement in Mortar and Concrete Elements: A Systematic Review
by Gloria Cosoli, Alessandra Mobili, Francesca Tittarelli, Gian Marco Revel and Paolo Chiariotti
Appl. Sci. 2020, 10(24), 9152; https://0-doi-org.brum.beds.ac.uk/10.3390/app10249152 - 21 Dec 2020
Cited by 53 | Viewed by 8477
Abstract
This paper aims at analyzing the state-of-the-art techniques to measure electrical impedance (and, consequently, electrical resistivity) of mortar/concrete elements. Despite the validity of the concept being widely proven in the literature, a clear standard for this measurement is still missing. Different methods are [...] Read more.
This paper aims at analyzing the state-of-the-art techniques to measure electrical impedance (and, consequently, electrical resistivity) of mortar/concrete elements. Despite the validity of the concept being widely proven in the literature, a clear standard for this measurement is still missing. Different methods are described and discussed, highlighting pros and cons with respect to their performance, reliability, and degree of maturity. Both monitoring and inspection approaches are possible by using electrical resistivity measurements; since electrical resistivity is an important indicator of the health status of mortar/concrete, as it changes whenever phenomena modifying the conductivity of mortar/concrete (e.g., degradation or attacks by external agents) occur, this review aims to serve as a guide for those interested in this type of measurements. Full article
(This article belongs to the Special Issue Non-destructive Testing in Civil Engineering)
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