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1
Milovanović, Bojan, Mergim Gaši, and Sanjin Gumbarević. "Principal Component Thermography for Defect Detection in Concrete." Sensors 20, no. 14 (July 13, 2020): 3891. http://dx.doi.org/10.3390/s20143891.
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The goal of the condition assessment of concrete structures is to gain an insight into current condition of concrete and the existence of defects, which decrease durability and usability of the structure. Defects are quite difficult to detect using infrared thermography when concrete elements cannot be thermally excited with the Sun, together with unfavorable thermophysical properties of concrete structures. In this paper, principal component thermography (PCT) is applied as a post-processing method to a sequence of thermograms in order to enhance defect detectability in concrete structures. Defects are detected by analyzing a set of empirical orthogonal functions (EOFs), which were acquired by applying principal component analysis to a sequence of thermograms. The research was performed using concrete samples containing known defects, which were tested using a step heating thermography setup. The results of presented research show that PCT is an effective post-processing method to improve defect detection in concrete structures. By effectively improving the defect detection, PCT has a potential to improve the non-destructive testing (NDT) accuracy of using infrared thermography (IRT) on concrete structures, especially in shaded areas of such structures. The research also shows the defect detectability depending on concrete type thermal excitation setup and defect geometry.
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Wen, Bo, Zhenwei Zhou, Bin Zeng, Caiqian Yang, Da Fang, Qing Xu, Yanchao Shao, and Chunfeng Wan. "Pulse-heating infrared thermography inspection of bonding defects on carbon fiber reinforced polymer composites." Science Progress 103, no. 3 (July 2020): 003685042095013. http://dx.doi.org/10.1177/0036850420950131.
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Non-destructive analysis of fiber reinforced polymer (FRP) composites is important for confirming the long-term safety and durability of concrete structures. In this study, a pulse-heating infrared thermography technique was used to detect and characterize bonding defects of externally bonded carbon fiber reinforced polymers (CFRP) on concrete surface structures. The CFRP composite contains various bonding defects of three different sizes located at five different depths. Sequential thermal images were obtained to describe the temperature contrast and shapes of the bonding defects. Through analysis of the maximum temperature response, we investigated the effects of defect size and depth on the defect temperature response. The relationship between the defect depth and maximum temperature response was used to quantitatively estimate the defect depth. In addition, finite element simulations were performed on the CFRP composites with bonding defects to investigate the temperature response of various defects, which showed good agreement with the experimental results. This confirms the effectiveness of the infrared thermography method to detect and characterize bonding defects of FRP composites bonded on concrete structures.
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Liu, De Zhi, Jian Min Ren, and Yang Yang. "Ultrasonic Sector Scanning Method in the Application of the Accurate Determination of the Concrete Bored Pile Defect Position." Advanced Materials Research 430-432 (January 2012): 1128–32. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.1128.
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Based on the detection of cast-in-place concrete defects of bored pile as the research object, the scale of the commonly used method for measuring the determination of the defect position, which can't determine the accurate range is very large defect location of the problem, taking the first measurement method, planing initially determined by fan scanning method to determine the accurate out concrete piles defect position method, and digging pile defect position after the actual situation comparison of verifying test, test results are accurate effect and good. In the concrete bored piles detection, the level measurement method that ultrasonic testing is generally used for measuring the location range of the defects inspects too large range , which brings the inspection people can't determine the accurate defect position , affects the normal construction. Based on the engineering practice of using level measuring method and fan scanning technique combining detection methods to solve the determination on the accurate location of the defects in concrete bored piles.
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Fujii, Hiromitsu, Atsushi Yamashita, and Hajime Asama. "Boosting-based Visualization of Concrete Defects for Hammering Inspection." Abstracts of the international conference on advanced mechatronics : toward evolutionary fusion of IT and mechatronics : ICAM 2015.6 (2015): 55. http://dx.doi.org/10.1299/jsmeicam.2015.6.55.
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Qin, Renyuan, Denvid Lau, Lik-ho Tam, Tiejun Liu, Dujian Zou, and Ao Zhou. "Experimental Investigation on Interfacial Defect Criticality of FRP-Confined Concrete Columns." Sensors 19, no. 3 (January 24, 2019): 468. http://dx.doi.org/10.3390/s19030468.
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Defects between fiber reinforced polymer (FRP) and repaired concrete components may easily come out due to misoperation during manufacturing, environmental deterioration, or impact from external load during service life. The defects may cause a degraded structure performance and even the unexpected structural failure. Different non-destructive techniques (NDTs) and sensors have been developed to assess the defects in FRP bonded system. The information of linking up the detected defects by NDTs and repair schemes is needed by assessing the criticality of detected defects. In this study, FRP confined concrete columns with interfacial defects were experimentally tested to determine the interfacial defect criticality on structural performance. It is found that interfacial defect can reduce the FRP confinement effectiveness, and ultimate strength and its corresponding strain of column deteriorate significantly if the interfacial defect area is larger than 50% of total confinement area. Meanwhile, proposed analytical model considering the defect ratio is validated for the prediction of stress–strain behavior of FRP confined columns. The evaluation of defect criticality could be made by comparing predicted stress–strain behavior with the original design to determine corresponding maintenance strategies.
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Zhao, Guoqi, Di Zhang, Lu Zhang, and Ben Wang. "Detection of Defects in Reinforced Concrete Structures Using Ultrasonic Nondestructive Evaluation with Piezoceramic Transducers and the Time Reversal Method." Sensors 18, no. 12 (November 28, 2018): 4176. http://dx.doi.org/10.3390/s18124176.
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Reinforced concrete is of vital importance in many civil and industrial structural applications. The effective bonding between steel and concrete is the core guarantee of the safe operation of the structures. Corrosion or other interface debonding in steel-concrete is a typical failure mode during the long service period of the structures, which can severely reduce the load-bearing capacity. The Non-destructive Evaluation technique has been applied to civil engineering structures in recent years. This paper investigates the evaluation of reinforced concrete structures that have interface defects, including the cross-sectional loss and cracks, by using the piezoceramic induced ultrasonic wave and time reversal method. Ultrasonic wave is used as actuating wave to obtain the signals with defect information. Time reversal method is applied to localize and characterize defect along the interface of the steel-concrete and to image the defect through the cross-sectional scanning. Experiments were conducted to perform Nondestructive Evaluation by using six reinforced concrete components with different levels of defects. The invisible damages were made by the cutting part of the steel and embedding a table tennis ball inside concrete structures. The results show that the time reversed method can locate and evaluate the defects along the steel reinforced concrete, and the obtained defect images at the cross-section of the concrete structure are accurate.
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Zou, Zhong Quan, Xu Wang, and Zhi Mei Wang. "Application of Ultrasonic Testing in Concrete Filled Steel Tubular Arch Bridge." Advanced Materials Research 639-640 (January 2013): 1025–28. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.1025.
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Concrete Filled Steel Tube(CFST) is widely used in civil engineering structures because of its superior mechanical performance. Yet the mechanical behavior of CFST is highly depended on the construction quality of the filled concrete. Hence it is very important for the inspection of the construction quality of the filled concrete in CFST structures. In this paper, the ultrasonic testing technique was used to detect the defect of the filled concrete of a CFST arch bridge. During the inspection, the ultrasonic transducer was moved along the circumference of the cross-section of the arch, and the defect of the concrete was comprehensively judged by detecting the change of sonic time, sonic amplitude and sonic frequency. Based on the analysis of the ultrasonic transmission path, the influences of different defects on the sonic time, sonic amplitude and sonic frequency were discussed. The detecting results were verified by core-drilling method. The verification showed that different kinds of defects defected by ultrasonic testing was in good accordance with the drilling samples, which demonstrates the adaptability of the ultrasonic detection technique in the construction quality inspection of CFST structures.
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An, Van Viet Thien. "The assessment of concrete quality by ultrasonic pulse velocity." Journal of Science and Technology in Civil Engineering (STCE) - NUCE 12, no. 5 (August 30, 2018): 20–27. http://dx.doi.org/10.31814/stce.nuce2018-12(5)-03.
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In the present study, the uniformity and potential internal defects of concrete elements in situ were assessed by using Ultrasonic Pulse Velocity (UPV) testing method according to TCVN 9357:2012. Thirteen cross beams with dimension of 4.8 x 1.5 x 1.5 m3 were selected to measure the pulse velocity. Three cross beams were used to check potential internal defects in concrete and 10 cross beams were used to assess the uniformity of concrete in the elements. The results showed that there is no potential internal defect with size over 100 mm in three tested beams and concrete quality of all tested beams is good with the coefficient of variation (CV) of ultrasonic pulse velocity results of all tested points is lower than 2%.
Keywords: concrete; homogeneity; internal defects; ultrasonic pulse velocity.
9
Tazawa, E. "Defects in Concrete and Countermeasures." Concrete Journal 37, no. 10 (1999): 3–10. http://dx.doi.org/10.3151/coj1975.37.10_3.
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Li, Zuohua, Lilin Zheng, Chaojun Chen, Zhili Long, and Ying Wang. "Ultrasonic Detection Method for Grouted Defects in Grouted Splice Sleeve Connector Based on Wavelet Pack Energy." Sensors 19, no. 7 (April 6, 2019): 1642. http://dx.doi.org/10.3390/s19071642.
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Grouted splice sleeve (GSS) connectors are mainly used in precast concrete structures. However, errors in manual operation during construction cause grouted defects in the GSS connector, which can lead to a negative effect on the overall mechanical properties of the structures. Owing to the complex structure of precast concrete members with a GSS connector, it is difficult to detect grouted defects effectively using traditional ultrasonic parameters. In this paper, a wavelet packet analysis algorithm was developed to effectively detect grouted defects using the ultrasonic method, and a verified experiment was carried out. Laboratory detection was performed on the concrete specimens with a GSS connector before grouting, in which the grouted defects were mimicked with five sizes in five GSS connectors of each specimen group. A simple and convenient ultrasonic detection system was developed, and the specimens were detected. According to the proposed grouted defect index, the results demonstrated that when the grouted defects reached certain sizes, the proposed method could detect the grouted defects effectively. The proposed method is effective and easy to implement at a construction site with simple instruments, and so provides an innovative method for grouted defects detection of precast concrete members.
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Jin, Xian Yu, Nan Guo Jin, and Xiang Lin Gu. "Damage Analysis of Waterproof Layer in Composite Tunnel Lining Based on Theory of Plate with Large Deflection." Key Engineering Materials 400-402 (October 2008): 245–50. http://dx.doi.org/10.4028/www.scientific.net/kem.400-402.245.
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: In order to analyze the cause of water leakage in highway tunnels, the damage property of waterproof board in composite tunnel lining with concrete matrix defects under hydraulic pressure was studied using Galerkin method for plates with large deflection. The deflection, stress and strain of waterproof boards were calculated in the conditions of rectangular and elliptic boundary due to concrete matrix defects. First strength theory was used to determine the critical load of the board and the critical depth of the defect. Investigation results showed that the maximum principal stress generates in the middle of longer side in the rectangular boundary condition and in the center in the elliptic boundary condition, the failure of the waterproof board under certain hydraulic pressure is related with the dimensions of concrete matrix defects and the dimension of the concrete matrix defect needs to be controlled in the design and construction of waterproof layer for tunnels.
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Kim, Byeol, Yonghan Ahn, and Sanghyo Lee. "LDA-Based Model for Defect Management in Residential Buildings." Sustainability 11, no. 24 (December 16, 2019): 7201. http://dx.doi.org/10.3390/su11247201.
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This study systematically analyzes various defect patterns that occur during the warranty period of residential buildings using the loss distribution approach (LDA). This paper examines 16,108 defects from 133 residential buildings where defect disputes occurred between 2008 and 2018 in South Korea. The analysis results showed that the defect losses were relatively high in reinforcement concrete (RC) work (3/5/10 years), waterproof work (5 years), and finish work (2 years). It is shown that RC work has a high frequency of defects, such as cracks in concrete in public spaces affected by external factors. In addition, it was analyzed that the type of defect needed high repair cost because the area where the defect—such as incorrect installation and missing task—occurred, needed construction again. According to the level of frequency and severity, losses were divided within four zones to provide detailed strategies (by period). This will effectively contribute to minimizing unnecessary losses from defects as quantifying the losses of defects.
13
Xu, Ying, Chengyin Liu, Lei Chai, Miaomiao Lu, and Congcong Luo. "Failure mechanism of fiber-reinforced polymer-confined concrete column with initial defects." Journal of Composite Materials 52, no. 21 (February 19, 2018): 2887–97. http://dx.doi.org/10.1177/0021998318758882.
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The effect of initial defect size on the mechanical behavior and failure mode of carbon fiber-reinforced polymer- confined concrete column was investigated through theoretical analysis, finite element software simulation and experiment validation. Qualitative theoretical analysis was firstly explored to study the effect of initial defect size on the mechanical behavior of confined concrete column from macro to micro perspective. Numerical simulations and experimental investigation were then carried out and compared to investigate the mechanical behavior of carbon fiber-reinforced polymer-confined concrete column with initial defects under axial compression and eccentric compression. The variation of defect criticality was investigated by varying the layer number of carbon fiber-reinforced polymer and cross-section size of concrete columns. The effect of initial defect size on the failure mode of carbon fiber-reinforced polymer-confined concrete column was finally demonstrated.
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Krakhmalnyy, Timofey, and Sergej Evtushenko. "DEFECTS AND DAMAGES OF REINFORCED CONCRETE COLUMNS OF INDUSTRIAL BUILDINGS." Construction and Architecture 8, no. 2 (August 1, 2020): 5–10. http://dx.doi.org/10.29039/2308-0191-2020-8-2-5-10.
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This article is a continuation of the authors ' series of articles on defects and damage to building structures of industrial buildings. This article presents typical defects and damages of precast and monolithic reinforced concrete columns of industrial buildings. The possible reasons for the formation of typical defects, the consequences of which may lead to their development, are considered, and recommendations for the elimination of identified damages are given. In conclu-sion, the article analyzes the characteristic zones of defect formation in rein-forced concrete columns of buildings in accordance with the method proposed earlier by the authors.
15
Zhang, Rui Jin. "Effect of Steel-Concrete Interface on Reinforcement Corrosion in Marine Environment." Advanced Materials Research 250-253 (May 2011): 1311–14. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.1311.
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This paper dealt with the influence of the steel-concrete interface quality and environmental conditions on reinforcement corrosion. High size concrete members were cast to get different interface quality decreased with the height of rebar due to the top-bar effect. Five groups of specimen with two concrete covers have subjected to different exposed programs. The experimental results showed that the concrete cover significantly influenced corrosion initiation and corrosion rate by blocking the penetration of aggressive agents. The height of rebar affected the corrosion initiation because of the variation of concrete porosity, interface defects and chloride threshold. The existence of defects at the interface was more important than the size of defect for corrosion initiation.
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Liu, Lin, Qiang Wang, and Kai Guo. "Research on Evaluation Method of Ultrasonic Testing for Inspection of Concrete Jointing Surface Quality." Applied Mechanics and Materials 501-504 (January 2014): 877–80. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.877.
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The combining Part Of new-old concrete is a weak link. The cohesive strength of the combining layer is generally lower than the strength of the concrete poured completely. It will greatly affect the reliability of structure, when the combining layer is bad. It is a effective method to Inspect combining surface conditions by ultrasonic method. But related specification for defect judgment method of ultrasonic method, which is not fit to detect the defect area is larger in detect area, the overall quality of members is poor, make the discreteness of data less, those causes low judgment value, and the defects to leakage. In addition, the less data is not easy to found out the outliers. We adopted ultrasonic angle measurement method for concrete jointing surface of 50 pillars testing analysis, Method to determine the critical value of defect of abnormal value, and studied critical value determination method of defects outliers, propose a method of defects determination base on the common probability method. As detection is shown, first, with this method detect the joint surface of the concrete columns, contrasted core drilling results, prove the method is effective and feasible. Second, For new pouring concrete quality is poorer near surface, defect points too much, contrasted core drilling results, prove the method is effective and feasible. In addition, using this method for detecting data less, contrasted core drilling results, prove the method is effective and feasible.
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Ma, Jing, Yan Wang, and Ling Qiang Yang. "Numerical Simulation of Internal Defects in CSG Concrete (IV)." Advanced Materials Research 1065-1069 (December 2014): 1817–20. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.1817.
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The objective of this paper is to quantify the influence of internal defect on the multiaxial strength. Numerical analyses are performed for the second and third axial strength of the concrete. The analysis result indicated the existence of defects not only decreases the strength of materials, but also changed the stress state of the specimen.
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Liu, Jing, Jun Xie, Xiao Yu He, Yu Shan He, and Jia Hui Zhong. "Detecting the Defects in Concrete Components with Impact-Echo Method." Applied Mechanics and Materials 577 (July 2014): 1114–18. http://dx.doi.org/10.4028/www.scientific.net/amm.577.1114.
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With the large-scale application of the prestressed concrete structure, the quality of the concrete component defects and pipeline grouting has increasingly become the focus of attention. The impact-echo scanner uses the nature of wave, which pass though different media at different velocities, to distinguish internal defects of concrete, pipe filling density and so on. In this paper, using the impact-echo method to detect the concrete block with prefabricated defects of shape, location, and size explores the effect of defect properties, parameter settings and detection environment to impact-echo preliminarily and also explores the relationship of pipeline filling status and impact-echo image. Based on this study, the article raised the problem met during this non-destructive testing methods applied to engineering, and accumulated a certain amount of available engineering data. The experiment results show that using the impact-echo method to identify the defects of concrete components and to test the quality of pipeline grouting is a more convenient and effective non-destructive testing method. Especially, with the radar method in the pipeline grouting quality inspection which complement each other to make up for the shortcomings the lightning wave in case of the metal medium total reflection phenomenon, cannot detect metal pipe grouting plumpness.
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Peng, Gai Fei, Juan Yang, and Jing Yan Wang. "Influence of Recycled Aggregate Defects on the Durability of Recycled Aggregate Concrete." Key Engineering Materials 629-630 (October 2014): 173–82. http://dx.doi.org/10.4028/www.scientific.net/kem.629-630.173.
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An experimental investigation was conducted on the durability of recycled aggregate concretes with the water to binder ratios of 0.26 and 0.60, including chloride ion penetration resistance test, freezing-thawing resistance test and water penetration resistance. Natural aggregate, recycled aggregate untreated and recycled aggregate treated by sulfuric acid solution, were employed. Results indicated that, 3 mol/L acid concentration and the 7 days soaking duration was the optimum to remove the attached mortars in recycled aggregate, and its removal rate could reach to 90.8%. Water penetration resistance, chloride ion penetration resistance and freezing-thawing resistance of concrete with 0.26 W/B was superior to that of concrete with 0.60 W/B. The more pores in the internal of concrete with 0.60 W/B could be attributed to that. Durability of recycled aggregate concrete, incorporating recycled aggregate treated by sulfuric acid solution, was improved. In particular, the improvement in recycled high strength concrete was significant.
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Zheng, Wei Hua, and Zong Hua Wang. "Ant Colony Algorithm and Application in Inspection of Concrete Structure Defects." Applied Mechanics and Materials 204-208 (October 2012): 3201–5. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3201.
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BP neural network detecting concrete defect, convergence is slower and accuracy is not high. In order to overcome the defect of BP algorithm, using a combination of Ant Colony optimization algorithm and BP neural network method, a mathematical model of Ant Colony neural network was established, enables Ant Colony neural network training, and verify the validity of the method. And concluded: using ant Colony neural network identification of concrete defects, the identification of the location more effective than on size.
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Zhu, Jinsong, and Jinbo Song. "An Intelligent Classification Model for Surface Defects on Cement Concrete Bridges." Applied Sciences 10, no. 3 (February 2, 2020): 972. http://dx.doi.org/10.3390/app10030972.
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This paper mainly improves the visual geometry group network-16 (VGG-16), which is a classic convolutional neural network (CNN), to classify the surface defects on cement concrete bridges in an accurate manner. Specifically, the number of fully connected layers was reduced by one, and the Softmax classifier was replaced with a Softmax classification layer with seven defect tags. The weight parameters of convolutional and pooling layers were shared in the pre-trained model, and the rectified linear unit (ReLU) function was taken as the activation function. The original images were collected by a road inspection vehicle driving across bridges on national and provincial highways in Jiangxi Province, China. The images on surface defects of cement concrete bridges were selected, and divided into a training set and a test set, and preprocessed through morphology-based weight adaptive denoising. To verify its performance, the improved VGG-16 was compared with traditional shallow neural networks (NNs) like the backpropagation neural network (BPNN), support vector machine (SVM), and deep CNNs like AlexNet, GoogLeNet, and ResNet on the same sample dataset of surface defects on cement concrete bridges. Judging by mean detection accuracy and top-5 accuracy, our model outperformed all the contrastive methods, and accurately differentiated between images with seven classes of defects such as normal, cracks, fracturing, plate fracturing, corner rupturing, edge/corner exfoliation, skeleton exposure, and repairs. The results indicate that our model can effectively extract the multi-layer features from surface defect images, which highlights the edges and textures. The research findings shed important new light on the detection of surface defects and classification of defect images.
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Yang, Jing, Wei Heng Yuan, and Jun Tan. "Research on Non-Destructive Testing for Defects of Steel Bar in Concrete." Applied Mechanics and Materials 351-352 (August 2013): 143–47. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.143.
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Steel bar defect detection in concrete is an important content of civil engineering structure detection. Currently there are no effective methods for nondestructive testing of steel bar defects . This paper studies the application of electromagnetic induction technology for Steel bar defect detection. Firstly, the principle of electromagnetic induction technology to detect rebar are described. Secondly,an air dielectric test device was designed and Steel bar defect in the device was detected by magnetic scanner. Through analyzing we got the characteristics of scanning images from different Steel bar defects. Thirdly this experimental result was compared with detection result in concrete.Finally verify the accuracy and feasibility of this method.
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Wang, You Zhi, Yong Zhi Xu, and Ying Sun. "Experimental Study on Electrical Conductivity of Carbon Fiber Reinforced Concrete Underwater." Advanced Materials Research 461 (February 2012): 246–49. http://dx.doi.org/10.4028/www.scientific.net/amr.461.246.
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This paper studied the effect of carbon fiber dosage, concrete age, size of defect, and eater pressure on the electrical conductivity of carbon fiber reinforced concrete (CFRC). Insulating films were buried in the concrete to simulate inside cracking. The carbon fiber was added as the conductive material of the concrete. The electrical conductivity was measured with a two-electrode method with a DC power. The test results show that concrete age, defect area and the external water pressure are the main factors influencing the electrical conductivity of CFRC, while the number and location of defects have less effect.
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Wang, Juan, Qin Bing Li, and Long Bang Qing. "Interfacial Spring Element Model with Random Defects for 3D Simulation of Concrete Strength under Uniaxial Tension." Advanced Materials Research 243-249 (May 2011): 5975–80. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.5975.
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In this study, an interfacial spring element model with random defects was constructed based on the four-phase material model of concrete, which consists of aggregate, matrix, interfacial transition zone (ITZ), and initial defects distributing randomly within the ITZ. The ITZ is modeled by linear spring element of zero length. Simulation of concrete strength under uniaxial tension yielded numerical results that are consistent with reliable experimental data, thus proving that the model is reasonable and applicable. Then, the model was employed to analyze the influence of random initial defects on concrete strength. Results showed that increased initial defects in ITZ leads to a linear decrease in tensile strength of the concrete. Compared with the strength of concrete without initial defects, that of concrete with initial defects equal to 60 % of ITZ elements decreased by about 40%. Based on these results, this study recommends that the fraction of initial defects should be 30 % when using the proposed model to predict uniaxial tensile strength of normal-strength concrete.
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Gao, Bai Feng, Hui Jian Li, and Li Xin Zhang. "A Combined Ultrasonic Wave Nondestructive Testing Technique for Defect Detection in Concrete." Advanced Materials Research 41-42 (April 2008): 297–302. http://dx.doi.org/10.4028/www.scientific.net/amr.41-42.297.
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We describe the design and construction about the Ultrasonic method to determine the defects in concrete structure. The wave velocity and its energy are different when it transfers in the concrete material with various defects. The defects can then be detected according to the relative wave velocity and energy variations in concrete material. In the present paper, two methods contain both the wavelet analysis and the nerve network used to determine the relative wave energy change in concrete, and then we will evaluate the defects in material by energy change. The result shows that the present method can give an accurate measurement for the defects in concrete structure.
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Robles, Kevin Paolo V., Dong-Won Kim, Jurng-Jae Yee, Jin-Wook Lee, and Seong-Hoon Kee. "Electrical Resistivity Measurements of Reinforced Concrete Slabs with Delamination Defects." Sensors 20, no. 24 (December 11, 2020): 7113. http://dx.doi.org/10.3390/s20247113.
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The main objectives of this research are to evaluate the effects of delamination defects on the measurement of electrical resistivity of reinforced concrete slabs through analytical and experimental studies in the laboratory, and to propose a practical guide for electrical resistivity measurements on concrete with delamination defects. First, a 3D finite element model was developed to simulate the variation of electric potential field in concrete over delamination defects with various depths and lateral sizes. Second, for experimental studies, two reinforced concrete slab specimens (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)) with artificial delamination defects of various dimensions and depths were fabricated. Third, the electrical resistivity of concrete over delamination defects in the numerical simulation models and the two concrete slab specimens were evaluated by using a 4-point Wenner probe in accordance with AASHTO (American Association of State Highway and Transportation Office) T-358. It was demonstrated from analytical and experimental studies in this study that shallow (50 mm depth) and deep (250 mm depth) delamination defects resulted in higher and lower electrical resistivity (ER) values, respectively, as compared to measurements performed on solid concrete locations. Furthermore, the increase in size of shallow defects resulted in an increase in concrete resistivity, whereas the increase in sizes of deep delamination defects yielded opposite results. In addition, measurements done directly above the steel reinforcements significantly lowered ER values. Lastly, it was observed from experimental studies that the effect of delamination defects on the values of electrical resistivity decreases as the saturation level of concrete increases.
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Ismail, Zul-Atfi. "Lesson learned in maintaining the precast concrete buildings." Journal of Facilities Management 18, no. 3 (July 27, 2020): 341–59. http://dx.doi.org/10.1108/jfm-04-2020-0029.
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Purpose The purpose of this study is to identify existing weaknesses in precast concrete building maintenance and how to overcome it. The contemporary practice of conventional methods in the pre-cast concrete (PC) building maintenance entails many issues such as PC component aesthetic and structural defects, no integration between maintenance systems and lack the intelligent capabilities of linking defect diagnosis operations in maintenance due to poor service delivery and defect repetition. A key problem impeding the widespread adoption of emerging technologies is the lack of competent contractor supporting the effectiveness of implemented information and communication technology than conventional methods and the returns on investment. Design/methodology/approach The shortcomings of conventional methods are assessed from the perspective of PC buildings. Several data were collected through a case study of eight PC buildings from high-rise and complex buildings. Findings The conventional methods had significantly little emphasis on defect diagnosis tools. It had also increased the inadequate strategic decision making to analyse information in improving the maintenance project outcomes for PC building. Originality/value Building information modelling tools is suggested from findings and lessons learned as a good practice to reduce the repetition of defects on the design specification used and construction practiced.
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Tian, Xiu Shu, and Shuai Hou. "Detection of Defects in Layered Concrete Based on Rayleigh Surface Wave Method." Key Engineering Materials 815 (August 2019): 210–15. http://dx.doi.org/10.4028/www.scientific.net/kem.815.210.
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Based on the finite element model, the propagation characteristics of Rayleigh wave in layered structure is studied in this paper, the time-domain characteristics of wave form is analysed under different working conditions, and the identification parameters of surface wave method to detect the layered concrete is proposed. When the incident elastic wave propagates to the defect, due to the barrier effect of the defect, a part of the incident R wave is converted into a reflected R wave, which propagates along the track plate to the surface; the other part of the R wave is converted into a transmitted R wave, along the concrete. The energy amplitude can be used as one of the parameters to identify defects in the layered concrete structure.
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Hu, Tianyu, Jinhui Zhao, Ruifang Zheng, Pengfeng Wang, Xiaolu Li, and Qichun Zhang. "Ultrasonic based concrete defects identification via wavelet packet transform and GA-BP neural network." PeerJ Computer Science 7 (August 31, 2021): e635. http://dx.doi.org/10.7717/peerj-cs.635.
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Concrete is the main material in building. Since its poor structural integrity may cause accidents, it is significant to detect defects in concrete. However, it is a challenging topic as the unevenness of concrete would lead to the complex dynamics with uncertainties in the ultrasonic diagnosis of defects. Note that the detection results mainly depend on the direct parameters, e.g., the time of travel through the concrete. The current diagnosis accuracy and intelligence level are difficult to meet the design requirement for automatic and increasingly high-performance demands. To solve the mentioned problems, our contribution of this paper can be summarized as establishing a diagnosis model based on the GA-BPNN method and ultrasonic information extracted that helps engineers identify concrete defects. Potentially, the application of this model helps to improve the working efficiency, diagnostic accuracy and automation level of ultrasonic testing instruments. In particular, we propose a simple and effective signal recognition method for small-size concrete hole defects. This method can be divided into two parts: (1) signal effective information extraction based on wavelet packet transform (WPT), where mean value, standard deviation, kurtosis coefficient, skewness coefficient and energy ratio are utilized as features to characterize the detection signals based on the analysis of the main frequency node of the signals, and (2) defect signal recognition based on GA optimized back propagation neural network (GA-BPNN), where the cross-validation method has been used for the stochastic division of the signal dataset and it leads to the BPNN recognition model with small bias. Finally, we implement this method on 150 detection signal data which are obtained by the ultrasonic testing system with 50 kHz working frequency. The experimental test block is a C30 class concrete block with 5, 7, and 9 mm penetrating holes. The information of the experimental environment, algorithmic parameters setting and signal processing procedure are described in detail. The average recognition accuracy is 91.33% for the identification of small size concrete defects according to experimental results, which verifies the feasibility and efficiency.
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Liang, Ben Liang, and Ye Tian. "A Novel Defect Evaluation Method for Concrete Structures in Infrared Based on ANN and PSO Algorithm." Key Engineering Materials 439-440 (June 2010): 552–57. http://dx.doi.org/10.4028/www.scientific.net/kem.439-440.552.
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Abstract: The defect of concrete structures on material level can be expressed by defect depth and defect range. Infrared thermal imaging technology of concrete material defect detection is actually an inverse problem of heat transfer. On the basis of the current research achievements, infrared thermal imaging methods used in concrete structure defects was deduced to a multi-objective function optimization problem. Considering the traditional optimization algorithm slow convergence speed and local minima faults, this paper introduce particle swarm optimization algorithm (PSO) and the BP neural network to detect concrete material defect depth and range.PSO algorithm was used to optimize neural networks connection weights between layers and the network topology. The simulation test results are in good agreement with the experiment results and verify the validity of this method.
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Sadowski, Lukasz. "Non-Destructive Identification of Defects in Power Support Structure Foundations by Means of Acoustic Techniques." Key Engineering Materials 606 (March 2014): 95–98. http://dx.doi.org/10.4028/www.scientific.net/kem.606.95.
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Prefabricated power support structure foundations are made in prefabrication plants where concrete is laid in layers in moulds. The quality of the prefabricated units depends mainly on proper concrete mixture compaction, which is usually effected by means of immersion vibrators. It happens that when the vibrator is withdrawn too quickly, defects, in the form of, e.g., air voids and zones of insufficiently vibrated concrete, appear. Modern non-destructive acoustic techniques, which in recent years have been increasingly commonly used in the construction industry, are highly suitable for testing concrete elements, particularly prefabricated concrete units. The non-destructive impact-echo technique is particularly useful for determining defect location depth and for locating defective areas.
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Suleymanova, Ludmila A. "Technical Capabilities of Concrete and its Structure Defects." Materials Science Forum 974 (December 2019): 255–60. http://dx.doi.org/10.4028/www.scientific.net/msf.974.255.
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Theoretical and experimental materials for analyzing the technical capabilities of concrete are generalized and the physicochemical basis for the strength and durability of concrete is developed on the basis of the recent advances in building materials science and other sciences. That may increase the traditional concrete potential use and most importantly – to create the most firm and durable concrete of the new generation.
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Makhdoumi, Hamed, Seyyed Hesam Madani, Mehdi Shahraki, Mostafa Khodarahmi, and Naser Nosratzehi. "Comparison and Evaluation of Retrofitting Different Modes of Concrete Structures by FRP." Advanced Materials Research 1129 (November 2015): 242–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1129.242.
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Abstract. After recent earthquakes in the majority of seismic areas around the world including our country Iran and considering the irretrievable casualties and economic lost due to these earthquakes, natural catastrophic mitigation committees, research and scientific centers that are responsible for providing structural and seismic codes presented the concept of performance design, study of lifelines and retrofit and rehabilitation of existing and vital structures and the majority of researches in the field of earthquake engineering and structural engineering is focused on retrofit of structures considering economic and feasibility problems. Considering the increasing use of concrete structures in Iran and their substituting for steel structures ( due to weaknesses, constructional problems and defects) and considering the internal defects and failure modes, these structures should be retrofitted against earthquakes or preparations should be provided to decrease and minimize failure modes. concrete frames that consist of beam, column and connection is a essential part of concrete structures. Internal defect of concrete frame results in failure modes such as debonding and delamination in beams, buckling and torsion in column, local crashing in connection. Considering the several benefits of FRP sheets and their increasing use during years, these composites can be used for compressive-tensile, shear, bending, torsional retrofitting as well as for ductility increasing. In this study different types of failure modes of concrete frames and internal defects of them that lead to collapse are investigated. In addition different cases of retrofitting by FRP sheets to prevent failure modes and exciting defect are presented and these cases are compared.
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Yao, Zong Jian, Gui Lan Yu, Yue Sheng Wang, and Jian Bao Li. "Flexural Vibration in a Ternary Locally Resonant Phononic Crystal Thin Plate with Defects." Advanced Materials Research 150-151 (October 2010): 1282–85. http://dx.doi.org/10.4028/www.scientific.net/amr.150-151.1282.
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The improved supercell plane wave expansion method is applied to theoretically study the propagation of flexural waves in a ternary locally resonant phononic crystal thin plate with a point defect and linear defects. The thin concrete plate composed of a square array of steel cylinders hemmed around by rubber is considered here. Absolute band gaps in low frequency are obtained. For the point defect, the defect mode is localized around the defect, and the magnitude of the resonant defect mode is strongly dependent on the defect filling fraction, mass density and Young’s modulus of the defect cylinder. For the straight linear defects, several resonant linear defect bands appear inside the absolute band gap. And the displacement distributions show that the flexural waves could well propagate along the linear defects.
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Hüthwohl, Philipp, Ruodan Lu, and Ioannis Brilakis. "Multi-classifier for reinforced concrete bridge defects." Automation in Construction 105 (September 2019): 102824. http://dx.doi.org/10.1016/j.autcon.2019.04.019.
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Jiao, Liangbao, Qiling Ye, Xuehong Cao, Dryver Huston, and Tian Xia. "Identifying concrete structure defects in GPR image." Measurement 160 (August 2020): 107839. http://dx.doi.org/10.1016/j.measurement.2020.107839.
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Zheng, Dan, Shuaishuai Tan, Xinxin Li, and Haonan Cai. "Research on the Infrared Thermographic Detection of Concrete under Solar Heating." Advances in Civil Engineering 2021 (February 3, 2021): 1–10. http://dx.doi.org/10.1155/2021/6692729.
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Infrared thermography for detecting defects in concrete structures is closely related to the heat source and the optimized method of the thermal image. Due to the limitation of the irradiation area of the heat source, it is inefficient to detect the defects in large concrete structures. In this paper, sunlight was employed as a heat source to detect the defects with different sizes and depths in concrete, and the measured infrared images were processed and optimized by an enhancement algorithm. The experimental results showed that the defects in concrete could be rapidly identified under sunlight. The effect of environment, view angle, and boundary can be eliminated by image preprocessing, and the histogram equalization algorithm can increase the detection depth of the defects. The research results can also provide a reference for the infrared detection technology of concrete under the weak heat source.
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Desnerck, Pieter, Pierfrancesco Valerio, Janet M. Lees, and Neil Loudon. "Suggestions for improved reinforced concrete half-joint bridge inspection in England." MATEC Web of Conferences 199 (2018): 06004. http://dx.doi.org/10.1051/matecconf/201819906004.
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Asset management databases play a crucial role in the management of existing infrastructure assets. Highways England (HE) has a long history of using bridge management software to record the current state of bridges and to guide maintenance schemes and interventions. Reinforced concrete half-joints are amongst the most challenging structures to inspect and repair due to their susceptibility to deterioration and construction type. Hence, they require particular attention within asset management programmes. An Interim Management Strategy was developed by HE to identify all the structures on the Highways England road network with half-joint elements. These half-joint structures were then subjected to a special inspection regime. Out of the 428 half-joint structures with inspection data, 252 structures had defects associated with four existing HE defect classes. A review of the inspection database with a focus on half-joints led to an alternative classification of half-joint related defects based on a revised set of Defect Classes, the introduction of Defect Groups and the extraction of Defect Types specifically observed in half-joints. Using this new classification, the most common half-joint Defect Groups were found to be cracking, corrosion, spalling and deterioration mechanisms. In about half of the structures cracking and corrosion tended to be observed together. Correlations were also shown to exist between structural and deterioration, and constructional Defect Classes, emphasising the need for quality control and proper workmanship. Recommendations to address shortcomings in current inspection practice are proposed. Clearer defect definitions and decision-tree guidance for inspectors could enhance the consistency and repeatability of inspection data gathering thereby overcoming some of the limitations of subjective classifications. Acquiring additional information about the observed crack details including zonal information, crack patterns, crack extent, crack orientations and widths combined with local and global pictorial evidence would also be advantageous. This could then provide the basis for the automatic processing and identification of structures with specific half-joint related defects. In this way, asset managers would be better able to allocate limited resources to the most critical structures.
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YAMASHITA, Kentaro, Kunio GOKUDAN, and Tomoaki SAKAI. "OS11F060 Detection of Internal Defects in Concrete Structures by Analyzing Elastic Wave Propagation." Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2011.10 (2011): _OS11F060——_OS11F060—. http://dx.doi.org/10.1299/jsmeatem.2011.10._os11f060-.
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Wang, Zhong Wen. "Experimental Study of Defects in Cast-In-Situ Bored Piles and its Application for Superdeep Defect Treatment." Applied Mechanics and Materials 166-169 (May 2012): 434–40. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.434.
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Abstract. After the finishing of piles, it was found that concrete defects at 63.0m-67.0m at the No.1 Bored pile in the North Channel Bridge of Hangzhou Bay Bridge B13 pier, which is at a diameter of 250cm with length of 96m. Aiming to successful treatment for this kind of defects, the present study proposed the pressurized concrete injection treatment techniques for superdeep defects in bored piles. In the paper, the experiment was carried out in comparing various mixed proportions of grouting, and the relationship analyzed between compressive strength and sound velocity for the treatment process. From these data an empirical equation between sound velocity and strength was determined, and the curve established. Following the superdeep pressurized injection of concrete treatment technique, the bored pile was successfully treated for the defects, ensuring the pile foundation achieving design criteria.
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Sirca Jr., Gene F., and Hojjat Adeli. "INFRARED THERMOGRAPHY FOR DETECTING DEFECTS IN CONCRETE STRUCTURES." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 24, no. 7 (November 13, 2018): 508–15. http://dx.doi.org/10.3846/jcem.2018.6186.
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The traditional methods for inspecting large concrete structures such as dams and cooling towers require erecting large amounts of scaffolding to access the surface of the concrete structure in order to sound the concrete with an impact device or hammer to expose the damaged or defective areas. Another method for accessing the surface of a large concrete structure is to employ climbing inspections which poses a considerable safety risk. These traditional methods are used to determine defect or damage within a few inches of the surface. In addition to the logistic difficulty of these methods a hammer can cause damage if care is not taken. Further, it can cover only a small area. Infrared Thermography (IRT), also referred to as thermal imaging, utilizes the infrared spectrum to show differences in heat dissipating from a structure using a thermal imaging camera. This paper presents a review of the IRT research for detecting defects in concrete structures. Health monitoring and damage detection of large structures such as bridges and high-rise buildings has been a very active area of research in recent years. The two main approaches explored by researchers are vibration-based health monitoring and camera-based vision technology. IRT remains to be another promising technology for economical health monitoring of structures.
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Cotič, Patricia, Ernst Niederleithinger, Vlatko Bosiljkov, and Zvonko Jagliċiċ. "NDT Data Fusion for the Enhancement of Defect Visualization in Concrete." Key Engineering Materials 569-570 (July 2013): 175–82. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.175.
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Ground penetrating radar (GPR) and active thermography are well known non-destructive testing (NDT) methods for structural visualization and defect detection in concrete. However, for both methods, the probability of detection is strongly depth-dependent and each method suffers from an almost blind region at a specific depth. In this study we propose the use of unsupervised clustering techniques for the fusion of GPR and thermographic phase contrast data to enhance defect visualization in concrete. The evaluation was carried out on the basis of experimental data acquired on laboratory concrete test specimens, which contain inbuilt anomalies varying in shape, material and position. To achieve an optimal fusion of radar depth slices and thermographic phase contrast images along the depth axis, we derive sensitivity curves for both NDT methods and use the probability mass information to further improve the fusion results. Results show that the fuzzy c-means algorithm may contribute to an enhanced detection probability of defects below high density reinforcement. For defects with a concrete cover from 1.5 to 2 cm, the use of weighted clustering is particularly suggested. In general, complex defect types and shapes could be better resolved by using the Gustafson-Kessel algorithm or noise clustering. In addition, we demonstrate the application of the Dempster-Shafer theory to quantitatively evaluate the effectiveness of fused data on the basis of joint mass probability.
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Ding, Zude, Jincheng Wen, Xiafei Ji, Zhihua Ren, and Sen Zhang. "Experimental Investigation of the Mechanical Behavior of NC Linings in consideration of Voids and Lining Thinning." Advances in Civil Engineering 2020 (June 25, 2020): 1–14. http://dx.doi.org/10.1155/2020/8876785.
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The presence of voids or lining thinning directly affects the mechanical behavior of linings, and these defects threaten the safety of tunnel operation. In this study, a series of 1/5-scale model tests was used to investigate the mechanical behavior of normal concrete (NC) linings in consideration of voids and combined defects. Test results showed that the void and combined defects substantially reduced the load-bearing capacity and deformation properties of the linings. The inelastic mechanical behavior of the linings was also significantly affected by the defects. The effects of lining defects located at the spandrel were slightly weaker than those of lining defects located at the crown. As the void size or degree of combined defects increased, the tensile strain at the location of the lining defects also increased. Therefore, the defect position of the linings was easily damaged. The defects considerably reduced the overall deformation of the linings but increased the local deformation. The distribution of lining cracks was concentrated at the defect position. In addition, different failure characteristics of the lining were observed due to the differences in defects.
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Kee, Seong-Hoon, Jin-Wook Lee, and Ma Doreen Candelaria. "Evaluation of Delamination in Concrete by IE Testing Using Multi-Channel Elastic Wave Data." Sensors 20, no. 1 (December 30, 2019): 201. http://dx.doi.org/10.3390/s20010201.
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The main objectives of this study are to develop a non-destructive test method for evaluating delamination defects in concrete by the Impact-echo test using multi-channel elastic wave data and to verify the validity of the proposed method by experimental studies in the laboratory. First, prototype equipment using an eight-channel linear sensor array was developed to perform elastic wave measurements on the surface of the concrete. In this study, three concrete slab specimens (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)), with simulated delamination defects of various lateral dimensions and depth, were designed and constructed in the laboratory. Multi-channel elastic wave signals measured on the three concrete specimens were converted to the frequency-phase velocity image by using the phase-shift method. A data processing method was proposed to extract the dominant propagating waves and non-propagating waves from the dispersion images. The dominant wave modes were used to evaluate delamination defects in concrete. It was demonstrated that the surface wave velocity values were useful for characterizing the shallow delamination defects in concrete. In addition, the peak frequency of non-propagating wave modes extracted from the dispersion images gives information on the lateral dimensions and depths of the delamination defects. This study also discussed the feasibility of combined use of the results from propagating and non-propagating wave modes to better understand the information on delamination defects in concrete. As will be discussed, the multi-channel elastic wave measurements enable more accurate, consistent, and rapid measurements and data processing for evaluation of delamination defects in concrete than the single-channel sensing method.
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Nekrasov, Svetlana, Andrew Varlamov, Daliia Khamidulina, and Vladimir Rimshin. "Linear models of two-component structure." E3S Web of Conferences 135 (2019): 03058. http://dx.doi.org/10.1051/e3sconf/201913503058.
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Two-component model of the concrete composite was considered. The model is considered in two ways. Model “matrix - defects” and model of “matrix-filler”. In the model of “matrix - defects” we made the analysis of the behavior of the model depending on the number and distribution of defects in the body of the concrete prism. It is Described how to change in the number of defects in the process of loading a prismatic concrete specimen and their influence on strength and deformation properties of concrete. We obtained mathematical model of a two-component structure of concrete. We considered the changing deformation model of “matrix-filler” depending on the number and distribution of filler in the body of the concrete prism. Further models have been tested by comparison with computer models and experiments on standard prismatic specimens. It is revealed that the vertical cracks do not affect the vertical deformation of a prism.
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Zhong, Ruoyu, Ruichang Guo, and Wen Deng. "Optical-Fiber-Based Smart Concrete Thermal Integrity Profiling: An Example of Concrete Shaft." Advances in Materials Science and Engineering 2018 (September 9, 2018): 1–8. http://dx.doi.org/10.1155/2018/9290306.
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Concrete is currently the most widely used construction material in the world. The integrity of concrete during the pouring process could greatly affect its engineering performance. Taking advantage of heat production during the concrete curing process, we propose an optical-fiber-based thermal integrity profiling (TIP) method which can provide a comprehensive and accurate evaluation of the integrity of concrete immediately after its pouring. In this paper, we use concrete shaft as an example to conduct TIP by using the optical fiber as a temperature sensor which can obtain high spatial resolution temperature data. Our method is compared with current thermal infrared probe or embedded thermal sensor-based TIP for the concrete shaft. This innovation makes it possible to detect defects inside of the concrete shaft with thorough details, including size and location. First, we establish a 3D shaft model to simulate temperature distribution of concrete shaft. Then, we extract temperature distribution data at the location where the optical fiber would be installed. Based on the temperature distribution data, we reconstruct a 3D model of the concrete shaft. Evaluation of the concrete integrity and the existence of the potential defect are shown in the paper. Overall, the optical-fiber-based TIP method shows a better determination of defect location and size.
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Xu, Bin, Lele Luan, Hongbing Chen, Jiang Wang, and Wenting Zheng. "Experimental Study on Active Interface Debonding Detection for Rectangular Concrete-Filled Steel Tubes with Surface Wave Measurement." Sensors 19, no. 15 (July 24, 2019): 3248. http://dx.doi.org/10.3390/s19153248.
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Concrete-filled steel tube (CFST) members have been widely employed as major structural members carrying axial or vertical loads and the interface bond condition between steel tube and concrete core plays key roles in ensuring the confinement effect of steel tube on concrete core. An effective interface debonding defect detection approach for CFSTs is critical. In this paper, an active interface debonding detection approach using surface wave measurement with a piezoelectric lead zirconate titanate (PZT) patch as sensor mounted on the outer surface of the CFST member excited with a PZT actuator mounted on the identical surface is proposed in order to avoid embedding PZT-based smart aggregates (SAs) in concrete core. In order to validate the feasibility of the proposed approach and to investigate the effect of interface debonding defect on the surface wave measurement, two rectangular CFST specimens with different degrees of interface debonding defects on three internal surfaces are designed and experimentally studied. Surface stress waves excited by the PZT actuator and propagating along the steel tube of the specimens are measured by the PZT sensors with a pitch and catch pattern. Results show that the surface-mounted PZT sensor measurement is sensitive to the existence of interface debonding defect and the interface debonding defect leads to the increase in the voltage amplitude of surface wave measurement. A damage index defined with the surface wave measurement has a linear relationship with the heights of the interface debonding defects.
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Brueckner, Rene. "Concrete repair challenges in the Middle East." MATEC Web of Conferences 289 (2019): 10003. http://dx.doi.org/10.1051/matecconf/201928910003.
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The root cause analysis, determination of the extent of concrete defects and identification of an appropriate repair strategy can be straightforward, but it also often provides significant challenges to both contractors and engineers. The challenges can be due to a lack of QA/QC documentation, locally available investigation equipment, repair material and techniques and accepting actually feasible solutions. The paper presents a case study of a bridge in the Middle East where the root cause analysis was found to be straightforward but the determination of the extent of non-visible defects and the implementation of a feasible repair strategy proved to be much more complicated. The root cause analysis of the defects was carried out by visual inspection, representative intrusive investigations and a comprehensive document review. The determination of the extent of the defects using GPR techniques proved to be challenging under the local conditions. Even more difficulties were encountered by implementing the developed repair strategies to address the various defects to ensure that the required 120 years design life in a very aggressive environment can be achieved. Several revisions to the repair strategy were necessary to identify the most appropriate solution and to accelerate the programme.
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Shahiron, Shahidan, Norazura Muhamad Bunnori, Md Noor Noorsuhada, and Siti Ramziah Basri. "Health Index Evaluation on Acoustic Emission Signal for Concrete Structure by Intensity Analysis Method." Advanced Materials Research 403-408 (November 2011): 3729–33. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.3729.
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Concrete structures have been facing several types of damage mechanisms during their lifetime. Mostly, the types are commonly defects in concretes structures are crack formations. Therefore, evaluation methods such as acoustic emission (AE) are required for assessing the deterioration on concrete structures. This paper gives a brief on the evaluations of the acoustic emission signal strength to the health monitoring of reinforced concrete structure beam. Small scale size beam have been used for this investigation and the AE signal processing are the main principal data in this work for assessing by using the statistical quantitative technique, which is known as intensity analysis (IA).This type of technique is able to quantify and evaluate the damage severity on concrete structures. Eventually, by using the AE signal strength data, the results indicates are greater instruments in determining the damage mechanism level on concretes structure.
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Kamenchukov, Aleksey, Ilya Ukrainskiy, Nikina Bushuev, and Nikolay Kim. "Modeling of reflected cracks in asphalt concrete pavement of highways." Journal of Applied Engineering Science 19, no. 2 (2021): 466–74. http://dx.doi.org/10.5937/jaes0-29136.
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The paper considers the issues of crack resistance of multilayer systems made of asphalt concrete, namely: the causes and features of the occurrence and development of "reflected" cracks are investigated. A study of the operational state of highways was carried out and the prerequisites for the formation of defects on the pavement were determined, including the regional features of the work of the road structure. The authors comprehensively studied the causes of internal and external defects and deformations of asphalt concrete pavements. The most popular technologies for sealing cracks and restoring the pavement are considered, the experience of repairing roads in the western part of Russia, Europe and the USA is also investigated. The results of determining the rate of formation and development of defects in the surface of the exploited roads are presented. In laboratory conditions, work was carried out to simulate cracks in two-layer samples of fine-grained asphalt concrete. Test specimens with a height and diameter of 10 cm were made by molding and compacted in layers, a crack was laid in the lower layer of the specimen. After gaining strength, the samples were tested for compression. Analysis of the results of physical modeling made it possible to put forward an assumption about the existence of a relationship between the presence (absence) of internal defects in the coating and the strength of the structure. To confirm the hypothesis, mathematical modeling of the operation of a two-layer system in the GenIDE32 software package was performed. Evaluation of the stress-strain state by the finite element method showed the presence of characteristic zones of system weakening around the defect area. In a two-layer system, there is an increase in internal stresses and strains around the crack, as well as a decrease in the overall strength (stability) of the system. In conclusion, the influence of internal defects of asphalt concrete coatings on the process of formation of "reflected" cracks were identified.