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Reinforcement corrosion is a leading cause of damage in concrete bridge decks, resulting in cracking and spalling in the concrete cover. Recently, ground penetrating radar (GPR) emerged as a prominent non-destructive testing (NDT) for evaluating the corrosiveness of concrete structures. Although GPR provides real-time testing for concrete elements, the analysis and interpretation of GPR data can be complex and time-consuming. To this end, this paper introduces a comprehensive methodology for a fully automated GPR data interpretation in the context of reinforcement corrosion evaluation. The developed method encompasses robust rebar picking and corrosion mapping. The rebar picking is realized by employing advanced waveform analysis and a three-step automated thresholding approach. Following rebar picking and data extraction, corrosion mapping is performed, stepping on a statistically optimized amplitude thresholding process. The developed rebar picking module achieved more than 98% precision and recall. Furthermore, the standardized corrosion assessment methodology precisely pinpointed potential corroded areas. [Display omitted] • Waveform analysis and three-step thresholding realized automated rebar recognition. • Corrosion is precisely mapped using standardized analysis and optimized thresholds. • The model achieved high rebar picking accuracy and accurate corrosion mapping. • The proposed framework advances strides toward a smart bridge inspection. [ABSTRACT FROM AUTHOR]

Reinforcement corrosion is a common cause of damage in concrete structures, resulting in cracking and spalling of the surrounding concrete. Recently, ground penetrating radar (GPR) has become the primary non-destructive testing (NDT) for examining the corrosiveness of concrete structures. However, the analysis of GPR data can be intricate and time-consuming due to a range of factors affecting GPR waves. To this end, this paper presents a systematic review of influential factors and analysis methods for GPR-based corrosion assessment in concrete structures. The review analysis found that corrosion boosts the reflected waves' amplitude by propagating rust into concrete cracks, while the simultaneous presence of chloride and moisture severely attenuates the amplitude and frequency of electromagnetic waves. In addition, B-scans analysis is more thorough but also subjective and time-consuming and lacks for comprehensive methodology to automate its process. Thereafter, this study offers insights for improving the efficiency of GPR-based corrosion assessment. [Display omitted] • Scientometric and systematic reviews were leveraged to study uses of GPR for corrosion assessment in concrete structures. • The impact of the physical, environmental, and technical factors on the GPR signal was reviewed. • Various GPR analysis methods for corrosion assessment were compared. • Future prospects were suggested to ameliorate the efficiency of GPR-based corrosion assessment in concrete structures. [ABSTRACT FROM AUTHOR]

The growing problem of bridge deterioration globally has imposed prominent challenges on transportation agencies, mainly in terms of ensuring safety and serviceability of the bridge infrastructure. The large number of bridges built during the 20th century has aged and produced a complex decision-making problem that departments of transportation need to deal with. Bridge management, as a particular domain of infrastructure asset management, has focused on developing methods for condition rating and deterioration modeling. The current research reviews bridge inspection practices and identifies the main defects and deterioration signs of concrete bridge decks that are typically captured by Visual Inspection (VI) and Non-Destructive Evaluation (NDE) techniques. The research introduces the Quality Function Deployment (QFD) theory and Weibull Distribution Function (WDF) as an integrated novel method to the area of bridge condition assessment and deterioration modeling. The proposed QFD condition assessment model is developed based on integrating VI and Ground Penetrating Radar (GPR) evaluation results to provide consistent condition ratings and performance predictions. The QFD model is demonstrated with a real case study and compared to other condition assessment models. Moreover, the QFD method is validated with data extracted from twenty bridge inspection reports completed by bridge inspectors and assessed by bridge experts. The developed deterioration curves using the reliability function for the Weibull distribution show absolute matching in these results through predicting the structure future performance and defining its useful service life. Accordingly, these models can enhance bridge Maintenance, Repair and Replacement (MRR) decisions since they produce reliable condition ratings and predictions that can link to proper rehabilitation action, and eventually assist in the decision making and planning for the selected MRR action. All these processes are integrated within one framework. [ABSTRACT FROM AUTHOR]

This paper presents newly developed method for detecting and locating leaks in water distribution networks utilizing two detection techniques; ground penetrating radar (GPR) and infrared photography (IR). The experimental work and field investigation were carried out over 2 years in three locations in City of Doha, Qatar to capture 115 IR image frames and 23 GPR image frames. Firstly, GPR technology is utilized to accurately define location of buried pipes. After locating these pipes, IR images are collected for simulated and actual leaks. The developed algorithm segments each image into leakage and non-leakage areas and the centroid of each leakage is calculated using Green's theorem. Subsequently, GPR images are introduced as a second layer and overlaid with IR images to compare pipes location with leak location. The method was successfully applied to detect simulated and actual leaks in summer and winter seasons with small margin of error (2.9–5.6%) in estimating leakage areas. When examining the investigated four operating conditions, it was found that the developed method can predict leaks in a more reliable way if the camera height is 2 m and the speed is 1.65 m/s in both simulated and actual leaks. The newly developed method is robust and can aid operators and city engineers in detecting and locating water leaks with high accuracy. [ABSTRACT FROM AUTHOR]

Abstract Ground-penetrating radar (GPR) is one of the most commonly used technologies for condition assessment of concrete bridge decks. However, there have been no fully automated algorithms to visualize the data collected with this technique. In such context, the current paper presents a method for a full automation of GPR data visualization and analysis. Based on the background removal, depth correction, synthetic aperture focusing technique (SAFT), and interpolation algorithms, this automated method produces a plan view map of amplitude of GPR signals. In the obtained map, two types of information are observed at the same time. First, as the strongest reflectors of electromagnetic energy, rebars will appear as the most visible. Second, the areas of corrosive environment and, thus, likely corrosion, will be detected as having low amplitude rebar reflections. As a proof of concept, the proposed method was implemented for two bare concrete bridge decks and two concrete bridge decks with asphalt overlays. In all cases, the results obtained were excellent where the maps pinpointed the areas affected by corrosion. These areas were confirmed by other methods of evaluation, such as electrical resistivity (ER), half-cell potential (HCP), chloride analysis of core samples, or visual inspection. With the demonstrated performance, the proposed method is expected to be an excellent alternative to the available methods of GPR data evaluation and visualization. In the future, it should be improved to provide an indication of corrosion severity/probability at each deck location. [ABSTRACT FROM AUTHOR]

This study presents a workable procedure for developing and updating deterioration prediction models based on the results of a Non-Destructive Evaluation (NDE) technique, Ground Penetrating Radar (GPR). To this end, a system reliability based deterioration model was developed for a simply-supported reinforced concrete bridge deck, designed according to the Canadian Highway Bridge Design Code (CHBDC-S6). The superstructure element-level deteriorated conditions for different time intervals were applied in the non-linear finite element model developed for the entire bridge deck, and the system level reliability indices were estimated accordingly. The salt contamination was assumed to affect the top surface, soffits of the deck, and beams due to infusion of de-icing salt material. The resulting primary deterioration model was updated based on a GPR test localized defect map that was obtained for an existing bridge with similar plan dimensions. The results indicate that the assumed conservative uniformly defected superstructure is reliable in this case, that is, the estimated reliability indices for the uniform and localized defect plans do not differ considerably. [ABSTRACT FROM AUTHOR]

• A model to detect and map air/water voids in subway systems is developed. • The methodology is based on image analysis of GPR profiles. • A deterioration map that delineates air/water voids zones is generated automatically. • The proposed scheme is applied to a concrete tunnel in Montreal Metro. • Validation via digital images, coring, infrared thermography and laser techniques. Water infiltration through soil is deemed the most serious problem and the main cause of concrete degradation in subway facilities. A huge amount of water intrusion may accelerate the deterioration mechanisms, such as rebar corrosion, spalling, and water voids. Such mechanisms can compromise the structural integrity and jeopardize public safety. The inspection and assessment of concrete structures are predominantly conducted based on visual inspection technologies. Although, these techniques may be consistent in detecting surface defects, e.g. cracks and spalling, they fall short in identifying subsurface distresses such as air voids, and water voids. Ground Penetrating Radar (GPR) has been extensively utilized for probing concrete infrastructure. Nevertheless, the deterioration mapping of air voids and water voids in concrete has seldom been performed. The objective of this paper is to develop an integrated model based on image processing of GPR profiles to automate air/water voids detection and mapping in subway systems. First, an automated localization scheme is developed to create a consistent inspection pattern. Second, subsurface data are collected in a subway facility, and processed using the image-based analysis technique. Third, the locations and dimensions of the detected defects are mapped to evaluate the severity of deterioration. The developed method is implemented on a tunnel in Montreal subway network. Then, validated via field inspection, digital images, coring samples, infrared thermography and 3D laser techniques. The validation outcomes reflect a strong correlation and compatibility with the generated GPR-based maps. The proposed framework is expected to assist infrastructure managers in identifying critical deficiencies and by focusing constrained funding on most deserving assets. [ABSTRACT FROM AUTHOR]

Ground Penetrating Radar (GPR), a locating instrument by design, has attracted much interest as a non-destructive inspection technique for bridge decks due to its ease of use and ability to detect corrosion. The most commonly used technique to interpret GPR data is numerical analysis. The assessment method relies on the fact that corroded reinforcing bars, which cause signal attenuation, can be easily identified using GPR scans. However, several other unrelated factors can attenuate GPR signals such as reinforcing bar depth, surface anomalies and reinforcing bar spacing. These anomalies can be falsely interpreted as deterioration using numerical analysis. Image-based analysis overcomes these drawbacks through analyzing the entire GPR profile while considering prior knowledge of the structure characteristics, thus determining the state of bridge deck. The main objective of this research is to develop a systematic framework of the image-based analysis. The framework is supported by various GPR profiles depicting several causes of signal attenuation and their analysis with respect to deterioration or rebar corrosion status. Two case studies are presented and analyzed using numerical analysis, image-based analysis, and other Non-Destructive Evaluation (NDE) techniques. The results are compared to confirm the validity of the proposed methodology. Further validation is done using concrete cores. The developed approach is believed to assist transportation agencies in a more informed decision making process through highlighting areas of actual deterioration. [ABSTRACT FROM AUTHOR]

The condition assessment of civil engineering concrete-made structures has been a prevalent research area over the last thirty years as a result of concrete deterioration mechanisms that may compromise the integrity and durability of civil infrastructure. Ground Penetrating Radar (GPR) has been extensively used for the inspection and probing of concrete structures. Nevertheless, a comprehensive state-of-the-art review on the developments of condition assessment of concrete-made structures using GPR in a civil engineering perspective is missing in the literature. This paper aims at addressing the abovementioned limitations and contributes to the body of knowledge by leveraging a mixed methodology approach that incorporates the scientometric and systematic analyses on research work related to the condition assessment of civil constructions. Scopus database is used in this study where the state-of-the-art of GPR-based condition assessment models for civil engineering systems is described in conjunction with models' contributions, shortcomings, methodologies, and critiques. These systems include roads, bridges, structures, concrete elements, tunnels, and other civil engineering disciplines such as underground pipes and treatment plants. Finally, future research directions are recommended to guide the civil engineering community in identifying the crucial topics to be explored in the upcoming years. • Developments of condition assessment of concrete-made structures using GPR were reviewed. • Mixed review method was adopted to provide an in-depth understanding of 105 studies in a civil engineering context. • Civil engineering systems such as roads, bridges, structures, concrete elements, and tunnels are included in this study. • GPR-based condition assessment models' contributions, shortcomings, methodologies, and critiques were described. • Future directions to guide the civil engineering community in identifying crucial topics to be explored are recommended. [ABSTRACT FROM AUTHOR]