Non-destructive Testing Of Concrete Research Articles

Concrete Non-destructive Testing Technology and Its Application

Nondestructive testing of concrete has a very important position in the construction industry, this paper explains the nondestructive testing, introduces the necessity of nondestructive testing in a number of aspects, classifies the nondestructive testing technology of concrete, introduces the characteristics of several types of nondestructive testing, explains the current application of nondestructive testing in various fields of construction, the problems of nondestructive testing.

USE OF MAGNETIC NON-DESTRUCTIVE TESTING TO EVALUATE THICKNESS OF CONCRETE PROTECTIVE LAYER FOR ENCLOSING AND BEARING STRUCTURES AT NPP

Introduction. This article discusses methods and means of controlling the diameter and position of reinforcement and the thickness of the concrete protective layer, along with the contemporary techniques and devices for diagnostic and non-destructive testing of concrete. A comparative analysis of the applicability of contemporary devices was carried out.Aim. In this work, magnetic non-destructive testing was used to assess the thickness of the concrete protective layer, along with establishing the location of the upper row of rod reinforcement and embedded parts. Based on analyzing the interaction between the electromagnetic field of the sensor and the electromagnetic field of eddy currents induced by the source coil of the sensor in rebar, this method allows the diameter of the latter to be approximately estimated at an unknown protective layer.Materials and methods. As an example, the thickness of the concrete protective layer of enclosing structures (walls, floors) at power unit № 1 at the Kalinin Nuclear Power Plant (NPP) was measured using the POISK-2.6 device.Results. The analysis of design and as-built drawings for buildings and structures of the main facility of power unit № 1 at the Kalinin NPP was carried out. The state of passive fire protection equipment at the power unit (fire doors, cable penetration seals, and ventilation fire dampers) was evaluated. The actual thickness of the concrete protective layer and the location of the reinforcement of concrete elements at the facilities of the Kalinin NPP power unit were measured as per GOST 22904-93 using electromagnetic NDT. The applicability of the magnetic NDT for determining the thickness of the concrete protective layer was shown during the inspection of building structures.Conclusions. During the inspection of the facilities, it was established that the average thicknesses of the concrete protective layer, including the thickness of the reinforcement, range from 38 to 85 mm, with the diameter of the reinforcement of 12–20 mm. During the measurements, the applicability of the method was shown; it was also confirmed that the examined structures exhibit fire endurance of at least 90 minutes, which meets the requirements of regulatory documents.

Quantitative Non-Destructive Testing (NDT) of Submerged Civil Concrete Structures Using Remotely Operated Robotic Drones

Periodic inspection is of paramount importance to assess structural integrity and safety. Conventional concrete inspection procedures ranging from rebound hammer, to state-of-the-art ground penetrating radar and ultrasonic tomography focus on superstructures. Often, the part of the structure underwater, is subject to significant levels of corrosion. Today, qualitative visual inspection of the submerged surface can be performed by diving teams, wherein internal defects often go undetected. Furthermore, divers are limited to shallow depths and face several risks, especially when visibility is poor and operating in confined spaces. Presently, there are few commercially available quantitative NDT techniques for submerged structures. This paper presents an alternate solution to inspection of submerged concrete structures — using lightweight remotely operated vehicles (ROV) manufactured by Planys Technologies to perform concrete NDT underwater. Rebound hammer and ultrasonic pulse velocity techniques, although elementary, have been redesigned for use on a submersible drone. Several challenges were addressed including long-range communication and data acquisition, marinizing transducers and pulser-receivers, obtaining measurements in water currents and over deformed surfaces. Planys’ ROVs carry payloads including high-definition cameras, lasers, sonar, and underwater positioning systems to improve data-acquisition quality and location tagging of defects. Key results from experimental studies in a laboratory on canonical specimens are presented. Furthermore, the technology has been successfully tested in a port — details of the structure, operational arrangement and sample results from the field trial are also presented. Following calibration procedures, ROV based underwater concrete NDT was used to acquire data from the structure in grids and subsequently, identify zones of potential non-homogeneity. Numerous challenges, including interpretation of the time traces obtained, and correlation of results to structural integrity and to structures above water, are discussed in the paper. This work will be of interest to asset owners in marine, water management and power generation industries.

Investigation of nuclear concrete

Recent times, life extension of nuclear power plant (NPP) plays one of the crucial roles in energetics and especially in nuclear industry. Key members of NPP's long term operation are reactor pressure vessel (RPV) and its cavity (concrete shell surrounding nuclear reactor). There is big interest in prediction of the state of biological shielding concrete around RPV. Many countries all over the world solve more or less the same problem: how to predict its state? Recent article provides with an opportunity of biological shielding concrete non-destructive testing (NDT). Two NDT methods will be performed as a possible solution of the problem. Due to high radiation, mechanical manipulators have been applied in order to attach ultrasonic or acoustic-emission transducers onto concrete surface or steel liner surface. The results will show 1) the possibility of the measurement near nuclear reactor in its outage, 2) the testing of RPV cavity from Greifswald's NPP NORD 3) and also the measurement of concrete samples irradiated by neutron and gamma radiation in light water reactor LVR-15. All presented material leads to the same goal: prolong the durability of old nuclear power plants and/or access their reliability and/or guarantee their safety.

Research and application of a new type of aqueduct concrete non-destructive inspection robot based on the principle of coherent frequency

The concrete aqueduct has some quality problems such as lacuna and cavity during construction or operation, which seriously affects the safety of aqueduct operation. How to quickly detect the defects of aqueduct is of great significance to provide the basis for the repair and reinforcement of aqueduct. In this paper, based on the coherent frequency method, the automatic walking robot device for concrete nondestructive testing is integrated and assembled. Through wireless communication, the automatic excitation, acquisition and imaging of elastic wave are completed, so as to realize the rapid detection of uniformity and compactness defects of aqueduct concrete structure. Through the test and engineering demonstration application, the detection results are reliable, and the detection efficiency is improved by more than 50%. And the follow-up improvement plan of the system hardware should strengthen the maneuverability of the car, realize precise positioning, strengthen the energy of the seismic source, and improve the overall reliability of the system.

Prediction of the compressive strength of high-performance self-compacting concrete by an ultrasonic-rebound method based on a GA-BP neural network.

To address the problem of low accuracy and poor robustness of in situ testing of the compressive strength of high-performance self-compacting concrete (SCC), a genetic algorithm (GA)-optimized backpropagation neural network (BPNN) model was established to predict the compressive strength of SCC. Experiments based on two concrete nondestructive testing methods, i.e., ultrasonic pulse velocity and Schmidt rebound hammer, were designed and test sample data were obtained. A neural network topology with two input nodes, 19 hidden nodes, and one output node was constructed, and the initial weights and thresholds of the resulting traditional BPNN model were optimized using GA. The results showed a correlation coefficient of 0.967 between the values predicted by the established BPNN model and the test values, with an RMSE of 3.703, compared to a correlation coefficient of 0.979 between the values predicted by the GA-optimized BPNN model and the test values, with an RMSE of 2.972. The excellent agreement between the predicted and test values demonstrates the model can accurately predict the compressive strength of SCC and hence reduce the cost and time for SCC compressive strength testing.

Predicting the Compressive Strength of Concrete By Ultrasonic Pulse Velocity

The key resolution of non-destructive methods applied to concrete structures is to offer a suitable estimate of the quality of the material. One of the modern methods used in the test of concrete strength is the non-destructive testing applying the ultrasonic pulse velocity (UPV). In this study, the ultrasonic pulse velocity technique as non-destructive testing of concrete was used to distinguish concrete mixture design and show the predictive relationship between compressive strength and UPV. The effect of various grades of concrete (M15, M20, M25, M30, and M35) with water to cement ratio (w/c) of 0.45 and 0.5 were examined. It was observed that grade M15 cubes had the lowest transit time (37.6 – 41.2 µs) and grade M35 cubes had the highest transit time (48.7 – 49.9 µs) showing that the concrete with short transit time generates the highest pulse velocity than that with low transit time. Grade M15 cubes had the highest pulse velocity (3.6 – 4.0 km/s) and grade M35 cubes had the lowest pulse velocity (3.0 – 3.1 km/s). M15 cubes had the lowest actual compressive strength (18.1 – 19.3 N/mm2) and grade M35 cubes have the highest actual compressive strength (34.6 – 36.0 N/mm2). There was a good correlation between compressive strength and UPV. The study furthermore revealed that UPV can be used to accurately predict the compressive strength of concrete. For all concrete grades, the percentage variation did not exceed ± 2.5%.

赤外線サーモグラフィによるコンクリートの非破壊検査への思い

赤外線サーモグラフィによるコンクリートの非破壊検査への思い

Estimation on Embedment Length of Anchor Bolt inside Concrete Using Equation for Arrival Time and Shortest Time Path of Ultrasonic Pulse

The bearings or the seismic isolation bearings that play a critical role in bridge structures are fixed to the substructure by anchor bolts. However, the embedment depth of the constructed anchor bolts does often not reach the designed one and may lead to safety issues. The present study proposes an ultrasonic non-destructive testing (NDT) method to verify the embedment depth of the anchor bolts installed on bridges in-service. The P-wave of 50–100 kHz that is usually used in the NDT of concrete was transmitted from the head of the anchor bolt and its arrival time on the concrete cover was measured. The shortest arrival time of the ultrasonic pulse and the corresponding path were then analyzed to formulate their relationship and obtain the distance traveled by the ultrasonic pulse along the anchor by inverse analysis using the equation error estimation. The instability occurring in the inverse analysis is settled by regularization. Finally, the embedment depth of the anchor bolt can be estimated by the analysis of the graph plotting the position of the ultrasonic transmitter and the distance traveled by the pulse along the anchor. The proposed method is validated numerically and experimentally. The method is expected to contribute to the NDT of civil structures by making it possible to estimate the embedment depth of anchor bolts by the means of ultrasonic transducers using P-waves of 50–100 kHz.

Comparison of Ultrasonic Methods for Thermally Damaged Concrete Nondestructive Testing

Behaviour of concrete under elevated temperatures is very complex. There is a change of mechanical and physical parameters with temperature. In this paper we study the relations of thermal damage processes in concrete and parameters obtained by different ultrasonic methods. The concrete specimens were heated in programmable laboratory furnace. Selected temperature (200°C, 400°C, 600°C, 800°C, 1000°C and 1200°C) were maintained for 60 minutes. The first ultrasonic measurement technique in this paper was Ultrasonic Pulse Velocity method. The pulse velocity in a concrete depends on its density and its elastic properties. Therefore, it is possible to deduce the quality and the compressive strength of the concrete from the ultrasonic pulse velocity. The second ultrasonic measurement technique in this paper uses broadband pulse-compression signal, with variable amplitude to measure the change of fundamental frequency. This method is based on Nonlinear Elastic Wave Spectroscopy. Nonlinear Elastic Wave Spectroscopy methods takes advantage of the fact, that nonlinearities in material manifest themselves as a resonant frequency shifts and harmonics or dumping coefficients changes. The progress of nondestructive testing parameters was confirmed by results from the destructive tests.

Ultrasonic image reconstruction based on maximum likelihood expectation maximization for concrete structural information

Many problems in measurement data are the physical quantities which are used to reconstruct an image for non-destructive testing. Time of flight data ultrasonic computed tomography is used in concrete non-destructive testing. Here the maximum likelihood expectation maximization (MLEM) algorithm and ultrasonic time of flight data is used to evaluate concrete filled steel tubes. When the image is reconstructed with the measurement data, the image shows many artifacts and therefor it is difficult to find useful information from the reconstruction image. To obtain a high quality image, time of flight data interpolation and normalization are proposed for image reconstruction system. Experimental results indicate the successful identification of the steel tube position and shape, which is not filled with concrete. The results imply that the time of flight data for ultrasonic computed tomography as an effective method of using the time of flight tomography to enhance the soundness of evaluation for concrete filled steel tubes.

Nondestructive testing of concrete using highly nonlinear solitary waves

In this article, we describe the capability of a nondestructive evaluation (NDE) method at determining the strength of concrete surfaces. The method uses highly non-linear solitary waves (HNSWs) propagating inside a metamaterial in contact with the concrete to be tested. The metamaterial consists of a chain of spherical particles, and is part of a built-in transducer designed to excite and detect HNSWs. The NDE method exploits the dynamic interaction between the metamaterial and the concrete, and the hypothesis is that this interaction depends on the stiffness of the specimen being inspected. In this study, we tested this hypothesis by assembling two kinds of transducer and by casting cylinders with different water-to-cement ratios. The results show that the time of flight of the HNSWs is inversely proportional to the modulus of elasticity of the concrete. Once fully developed, the proposed NDE method may easily assess concrete surfaces.

Non-Destructive Testing of Concrete with Fine Recycled Aggregate

This paper is focused on non-destructive testing of concrete containing fine recycled aggregate (FRA). FRA was obtained from demolished concrete structures and crushed in the laboratory on fraction 0 – 4 mm. There were prepared four concrete mixtures. The first concrete mixture was control, did not include FRA. In other mixtures was natural replaced natural sand by FRA. There were tested workability of fresh concrete mixture and physical properties of hardened concrete. Finally, it is possible to say that the use of FRA influences the physical properties of concrete. The physical properties of concrete are connected with the durability of concrete. Therefore, it is necessary to focus on durability testing of FRA concrete in further research.

Non Destructive Testing of Concrete with Recycled Cement Powder

This study deals with determination of the physical properties of fine-aggregate concrete with partial replacement of cement in concrete mixture. Cement was replaced by recycled cement powder originating from construction and demolition waste. The main goal of this study is evaluation of the basic physical properties of the fine-aggregate concrete with partial cement replacement by recycled concrete powder such as density, water absorption capacity and capillary water absorption. The fine recycled concrete which was used as partial replacement of cement had the same grain size as cement. The replacement rate was 0 %, 5 %, 10 % and 15 %. Physical properties were investigated by using cubic and prismatic specimens.

The development and current state of methods for the nondestructive testing and acoustic tomography of concrete

The development of acoustic methods for the nondestructive testing of concrete during the recent decades is described. The main characteristic problems and tasks of acoustic tomography of concrete are outlined and the evolution of the methods of their solution is analyzed. The advantages and disadvantages of the synthetic-aperture focusing method as a tool for the visualization of the internal structure of concrete are discussed. Possible directions of further progress in theory, as well as practical acoustic tomography methods, including those using phase information, are indicated.

Application of Micro-Electro-Mechanical Sensors Contactless NDT of Concrete Structures.

The utility of micro-electro-mechanical sensors (MEMS) for application in air-coupled (contactless or noncontact) sensing to concrete nondestructive testing (NDT) is studied in this paper. The fundamental operation and characteristics of MEMS are first described. Then application of MEMS sensors toward established concrete test methods, including vibration resonance, impact-echo, ultrasonic surface wave, and multi-channel analysis of surface waves (MASW), is demonstrated. In each test application, the performance of MEMS is compared with conventional contactless and contact sensing technology. Favorable performance of the MEMS sensors demonstrates the potential of the technology for applied contactless NDT efforts. Objective: To illustrate the utility of air-coupled MEMS sensors for concrete NDT, as compared with conventional sensor technology.

Non-Destructive Testing of Concrete: A Review of Methods

This paper reviews the most common non-destructive testing (NDT) methods of concrete structures as utilized by the structural engineering industry. The fundamentals of NDT methods are explored in regards to their potential, limitations, inspection techniques and interpretations. The factors that influence the success of NDT methods are discussed and ways to mediate their influence are recommended. Reference is made to standard guidelines for the application and interpretation of the discussed NDT methods. NDT of concrete was found to be gaining increasing acceptance as a means of evaluating the strength, uniformity, durability and other properties of existing concrete structures. Perceptions of NDT inadequacy were attributable to lack of understanding construction materials and NDT methods themselves. The intent of this paper is to address these concerns by identifying and describing the most common successful methods of NDT as applied to concrete structures.

A Review of Ultrasonic Application on Non-destructive Testing Method for Concrete Structure

Although the technique of using ultrasound has reached maturity by given the extent of the development of sensors, but the use of the various areas still can be explore. Many types of ultrasonic sensors are still at conventional in use especially for measurement equipment in the industry. With the advancement of signal processing techniques, high-speed computing, and the latest techniques in image formation based Non-destructive testing (NDT) methods, the usage of ultrasound in concrete NDT testing is very extensive because the technique is very simple and should not damage the concrete structure to be investigated. Many of the parameters need to be tested using ultrasound techniques to concrete can be realized. Starting with the initial process for of concrete mixing until the concrete matured to the age of century old. Various tests are available to test a variety of non-destructive of concrete completely, in which there is no damage to the concrete, through those where the concrete surface is damaged a bit, to partially destructive testing, such as core tests and insertion and pull-off test, which surface to be repaired after the test. Testing parameter features that can be evaluated using non-destructive testing and destructive testing of some rather large and include basic parameters such as density, elastic modulus and strength and surface hardness and surface absorption, and reinforcement location, size and distance from the surface. In some cases it is also possible to check the quality of the workmanship and structural integrity of the ability to detect voids, cracks and delamination. A review of NDT using ultrasound on concrete are presented in this paper to highlight the important aspect to consider when one to consider the application and development of ultrasound testing on concrete by considering ultrasound signal capturing, processing and presenting.

Damage Evaluation of Concrete Based on Acoustic Emission <i>b</i>-Value

Acoustic emission (AE) is capable of real time continuous monitoring and it's not sensitive to the geometry of components,so it's widely used in nondestructive testing of concrete. The AE b-value occupies an important position in the study of concrete damage evaluation as a parameter of AE technology. The basic theory of AE b-value and the related technical problems of AE b-value calculation was discussed. Then the research of AE b-value on concrete was reviewed. At last, the AE b-value in the damage process of cement mortar (CM) and polypropylene diber reinforced mortar (PFRM) under compression was studied and concluded that the trend of AE b-value of CM and PFRM was obviously different.The AE b-value is closely related to the formation and propagation of cracks in the damage process of concrete and it declines rapidly before final fracture occurs.

Assessment of high strength and light weight aggregate concrete properties using ultrasonic pulse velocity technique

In this study, the ultrasonic pulse velocity technique as a non-destructive testing of concrete was used to assess the effect of some criteria on high strength and light weight aggregate concrete. The study included several concrete mix design with ages of 7, 28 and 90 days. The effect of age, cement content, water ratio and slump on two concrete types was studied and discussed. The use of ultrasonic pulse velocity technique to assessconcrete strength and quality was a good choice for effects determination. Key words: Non destructive testing (NDT), ultrasonic pulse velocity (UPV), compressive strength, regression analysis.