Measuring Rebar Cover Depth in Rigid Pavements with Ground-Penetrating Radar

2005 ◽  
Vol 1907 (1) ◽  
pp. 80-85 ◽  
Author(s):  
Imad L. Al-Qadi ◽  
Samer Lahouar
Keyword(s):  
Ground Penetrating Radar ◽  
Concrete Slab ◽  
Average Error ◽  
Reinforcing Bars ◽  
Cover Depth ◽  
Rigid Pavements ◽  
Reflection Model ◽  
Nondestructive Investigation ◽  
Ground Penetrating ◽  
Processing Techniques

Ground-penetrating radar (GPR) is a nondestructive investigation tool that is usually used in flexible pavement evaluation to estimate the thicknesses of the various layers composing the pavement. GPR is also used in flexible pavements to detect subsurface distresses, such as moisture accumulation and air voids. For rigid pavements and bridge decks, GPR is used to measure the thickness of the concrete slab and detect the location of reinforcing bars (rebar). Rebar detection is typically achieved, in this case, when an experienced operator finds the rebar's classic parabolic signature in the GPR data. This paper presents image-processing techniques that can be used to detect the rebar parabolic signature automatically in GPR data collected from rigid pavements with a high-frequency ground-coupled antenna. After detection of the rebar, the reflected parabolic shape is fit to a theoretical reflection model to estimate the pavement's dielectric constant and the rebar depth. The algorithms were validated on GPR data collected from a known continuously reinforced concrete pavement section. The technique showed an average error of 2.6% on the estimated rebar cover depth.

scholarly journals Experimental Assessment of Rebar Corrosion in Concrete Slab Using Ground Penetrating Radar (GPR)

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ahmad Zaki ◽  
Megat Azmi Megat Johari ◽  
Wan Muhd Aminuddin Wan Hussin ◽  
Yessi Jusman
Keyword(s):  
Ground Penetrating Radar ◽  
Structural Damage ◽  
Concrete Slab ◽  
Steel Corrosion ◽  
Steel Reinforcement ◽  
Reinforcement Corrosion ◽  
Dc Power ◽  
Reinforcement Bar ◽  
Ground Penetrating ◽  
Corrosion Of Steel

Corrosion of steel reinforcement is a major cause of structural damage that requires repair or replacement. Early detection of steel corrosion can limit the extent of necessary repairs or replacements and costs associated with the rehabilitation works. The ground penetrating radar (GPR) method has been found to be a useful method for evaluating reinforcement corrosion in existing concrete structures. In this paper, GPR was utilized to assess corrosion of steel reinforcement in a concrete slab. A technique for accelerating reinforcement bar corrosion using direct current (DC) power supply with 5% sodium chloride (NaCl) solution was used to induce corrosion to embedded reinforcement bars (rebars) in this concrete slab. A 2 GHz GPR was used to assess the corrosion of the rebars. The analysis of the results of the GPR data obtained shows that corrosion of the rebars could be effectively localized and assessed.

scholarly journals Advanced GPR Signal Processing Techniques for Root Detection in Urban Environments

2020 ◽  
Author(s):  
Livia Lantini ◽  
Fabio Tosti ◽  
Iraklis Giannakis ◽  
Kevin Jagadissen Munisami ◽  
Dale Mortimer ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Root Systems ◽  
Urban Environments ◽  
Street Trees ◽  
Destructive Testing ◽  
Root Detection ◽  
Charitable Trust ◽  
Ground Penetrating ◽  
Processing Techniques ◽  
Non Destructive

<p>Street trees are widely recognised to be an essential asset for the urban environment, as they bring several environmental, social and economic benefits [1]. However, the conflicting coexistence of tree root systems with the built environment, and especially with road infrastructures, is often cause of extensive damage, such as the uplifting and cracking of sidewalks and curbs, which could seriously compromise the safety of pedestrians, cyclists and drivers.</p><p>In this context, Ground Penetrating Radar (GPR) has long been proven to be an effective non-destructive testing (NDT) method for the evaluation and monitoring of road pavements. The effectiveness of this tool lies not only in its ease of use and cost-effectiveness, but also in the proven reliability of the results provided. Besides, recent studies have explored the capability of GPR in detecting and mapping tree roots [2]. Algorithms for the reconstruction of the tree root systems have been developed, and the spatial variations of root mass density have been also investigated [3].</p><p>The aim of this study is, therefore, to investigate the GPR potential in mapping the architecture of root systems in street trees. In particular, this research aims to improve upon the existing methods for detection of roots, focusing on the identification of the road pavement layers. In this way, different advanced signal processing techniques can be applied at specific sections, in order to remove reflections from the pavement layers without affecting root detection. This allows, therefore, to reduce false alarms when investigating trees with root systems developing underneath road pavements.</p><p>In this regard, data from trees of different species have been acquired and processed, using different antenna systems and survey methodologies, in an effort to investigate the impact of these parameters on the GPR overall performance.</p><p> </p><p><strong>Acknowledgements</strong></p><p>The authors would like to express their sincere thanks and gratitude to the following trusts, charities, organisations and individuals for their generosity in supporting this project: Lord Faringdon Charitable Trust, The Schroder Foundation, Cazenove Charitable Trust, Ernest Cook Trust, Sir Henry Keswick, Ian Bond, P. F. Charitable Trust, Prospect Investment Management Limited, The Adrian Swire Charitable Trust, The John Swire 1989 Charitable Trust, The Sackler Trust, The Tanlaw Foundation, and The Wyfold Charitable Trust. This paper is dedicated to the memory of our colleague and friend Jonathan West, one of the original supporters of this research project.</p><p> </p><p><strong>References</strong></p><p>[1] J. Mullaney, T. Lucke, S. J. Trueman, 2015. “A review of benefits and challenges in growing street trees in paved urban environments,” Landscape and Urban Planning, 134, 157-166.</p><p>[2] A. M. Alani, L. Lantini, 2019. “Recent advances in tree root mapping and assessment using non-destructive testing methods: a focus on ground penetrating radar,” Surveys in Geophysics, 1-42.</p><p>[3] L. Lantini, F. Tosti, Giannakis, I., Egyir, D., A. Benedetto, A. M. Alani, 2019. “A Novel Processing Framework for Tree Root Mapping and Density Estimation using Ground Penetrating Radar,” In 10th International Workshop on Advanced Ground Penetrating Radar, EAGE.</p>

scholarly journals Soil water content estimation using ground penetrating radar data via group intelligence optimization algorithms: An application in the Northern Shaanxi Coal Mining Area

2020 ◽  
pp. 014459872097336
Author(s):  
Fan Cui ◽  
Jianyu Ni ◽  
Yunfei Du ◽  
Yuxuan Zhao ◽  
Yingqing Zhou
Keyword(s):  
Dielectric Constant ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Error Rate ◽  
Ground Penetrating Radar ◽  
Volumetric Water Content ◽  
Average Error ◽  
Average Error Rate ◽  
Ground Penetrating

The determination of quantitative relationship between soil dielectric constant and water content is an important basis for measuring soil water content based on ground penetrating radar (GPR) technology. The calculation of soil volumetric water content using GPR technology is usually based on the classic Topp formula. However, there are large errors between measured values and calculated values when using the formula, and it cannot be flexibly applied to different media. To solve these problems, first, a combination of GPR and shallow drilling is used to calibrate the wave velocity to obtain an accurate dielectric constant. Then, combined with experimental moisture content, the intelligent group algorithm is applied to accurately build mathematical models of the relative dielectric constant and volumetric water content, and the Topp formula is revised for sand and clay media. Compared with the classic Topp formula, the average error rate of sand is decreased by nearly 15.8%, the average error rate of clay is decreased by 31.75%. The calculation accuracy of the formula has been greatly improved. It proves that the revised model is accurate, and at the same time, it proves the rationality of the method of using GPR wave velocity calibration method to accurately calculate the volumetric water content.

scholarly journals Nonintrusive Depth Estimation of Buried Radioactive Wastes Using Ground Penetrating Radar and a Gamma Ray Detector

2019 ◽  
Vol 11 (2) ◽  
pp. 141 ◽  
Author(s):  
Ikechukwu Ukaegbu ◽  
Kelum Gamage ◽  
Michael Aspinall
Keyword(s):  
Bulk Density ◽  
Ground Penetrating Radar ◽  
Gamma Ray ◽  
Depth Estimation ◽  
Average Error ◽  
Density Estimates ◽  
Material Density ◽  
Linear Correction ◽  
Ground Penetrating ◽  
Gamma Ray Detector

This study reports on the combination of data from a ground penetrating radar (GPR) and a gamma ray detector for nonintrusive depth estimation of buried radioactive sources. The use of the GPR was to enable the estimation of the material density required for the calculation of the depth of the source from the radiation data. Four different models for bulk density estimation were analysed using three materials, namely: sand, gravel and soil. The results showed that the GPR was able to estimate the bulk density of the three materials with an average error of 4.5%. The density estimates were then used together with gamma ray measurements to successfully estimate the depth of a 658 kBq ceasium-137 radioactive source buried in each of the three materials investigated. However, a linear correction factor needs to be applied to the depth estimates due to the deviation of the estimated depth from the measured depth as the depth increases. This new application of GPR will further extend the possible fields of application of this ubiquitous geophysical tool.

scholarly journals Detection of Soil Pipes Using Ground Penetrating Radar

2019 ◽  
Vol 11 (16) ◽  
pp. 1864 ◽  
Author(s):  
Anita Bernatek-Jakiel ◽  
Marta Kondracka
Keyword(s):  
Ground Penetrating Radar ◽  
Minimum Diameter ◽  
Se Poland ◽  
Pipe Networks ◽  
Piping Systems ◽  
Soil Piping ◽  
Potential Possibility ◽  
Almost All ◽  
Ground Penetrating ◽  
Processing Techniques

Soil piping leads to land degradation in almost all morphoclimatic regions. However, the detection of soil pipes is still a methodological challenge. Therefore, this study aims at testing ground penetrating radar (GPR) to identify soil pipes and to present the complexity of soil pipe networks. The GPR surveys were conducted at three sites in the Bieszczady Mountains (SE Poland), where pipes develop in Cambisols. In total, 36 GPR profiles longitudinal and transverse to piping systems were made and used to provide spatial visualization of pipe networks. Soil pipes were identified as reflection hyperbolas on radargrams, which were verified with the surface indicators of piping, i.e., sagging of the ground and the occurrence of pipe roof collapses. Antennas of 500 MHz and 800 MHz were tested, which made possible the penetration of the subsurface up to 3.2 m and 2 m, respectively. Concerning ground properties, antenna frequencies and processing techniques, there was a potential possibility to detect pipes with a minimum diameter of 3.5 cm (using the antenna of lower frequency), and 2.2 cm (with the antenna of higher frequency). The results have proved that soil pipes meander horizontally and vertically and their networks become more complicated and extensive down the slope. GPR is a useful method to detect soil pipes, although it requires field verification and the proper selection of antenna frequency.

Detection of Sizes and Locations Air Voids in Reinforced Concrete Slab using Ground Penetrating Radar and Impact-Echo Methods

2015 ◽  
Vol 74 (3) ◽  
Author(s):  
Nurhayati Abdul Razak ◽  
Syahrul Fithry Senin ◽  
Roszilah Hamid
Keyword(s):  
Reinforced Concrete ◽  
Ground Penetrating Radar ◽  
Concrete Slab ◽  
Depth Estimation ◽  
Reinforced Concrete Slab ◽  
Air Voids ◽  
Impact Echo ◽  
Void Defects ◽  
Ground Penetrating ◽  
Air Void

 The presence of inevitable air void defects in reinforced concrete components due to poor quality control during construction can further aggravate the moisture and chloride penetration in concrete to accelerate the corrosion process of the reinforcing steel. Non-destructive test  (NDT) methods, Ground Penetrating Radar (GPR) and Impact-Echo (IE), are utilised tp detect the void defects. This study is to compare the accuracy and limitations of both methods in detecting the sizes and depths of the air voids. The sample is a 600 × 400 ×200 mm3 reinforced grade 40 concrete slab with embedded air voids in the sample. The air-voids are introduced in the concrete slab by positioning air-void plastic balls with diameters of 67, 45, 27, 20 and 3 mm each at the depths of 70, 80, 100, 80 and 80 mm, respectively, from the top surface of the slab. Results show that GPR can detect the air voids with sizes larger than 20 mm in diameter with error ranging from -8.9 to 30% from their actual diameters. The IE method is only able to detect the air voids depths and not the voids’ sizes. It is also observed that the void depth estimation acquired by GPR is more accurate only for large size void (67 mm), but for sizes less than that, IE is more accurate in determining their locations. Both methos should be considered for NDT application in detecting voids depending on which parameter accuracy is inticipated.  

scholarly journals GPR APPLIED TO RIGID PAVEMENT FROM SANTOS DUMONT AIRPORT, RJ

2014 ◽  
Vol 32 (2) ◽  
pp. 225
Author(s):  
Welitom Rodrigues Borges ◽  
Luís Anselmo Da Silva ◽  
Luciano Soares Da Cunha ◽  
Raimundo Mariano Gomes Castelo Branco ◽  
Márcio Muniz de Farias
Keyword(s):  
Electromagnetic Wave ◽  
Ground Penetrating Radar ◽  
Rio De Janeiro ◽  
Concrete Slab ◽  
Geophysical Investigation ◽  
Rigid Pavement ◽  
Ground Penetration Radar ◽  
Speed Of Propagation ◽  
Ground Penetrating ◽  
Pavement Thickness

ABSTRACT. This paper presents the results of a research performed by using Ground Penetration Radar (GPR) to evaluate the structure of the rigid pavement ofSantos Dumont Airport in Rio de Janeiro, Brazil. The GPR data profiles were acquired with 250 and 700 MHz shielded antennas. The geophysical investigation wasperformed along of 6 profiles, totaling 1432 meters of GPR sections. For calibration of the speed of propagation of electromagnetic wave were drilled three boreholesuntil the depth of 1.8 m. The results of GPR allowed the precise delineation of reflectors related to geotechnical interfaces (pavement thickness – concrete slab andmacadam) and geological (sand/embankment soil), showing the efficiency of this method in this case study.Keywords: GPR, concrete, rigid pavement, Santos Dumont Airport. RESUMO. Este trabalho apresenta o resultado de uma pesquisa desenvolvida usando Ground Penetrating Radar (GPR) para avaliar a estrutura do pavimento rígido do pátio de manobras de aeronaves do Aeroporto Santos Dumont, no Rio de Janeiro, Brasil. Para isso foram usadas antenas blindadas com frequências de250MHz e de 700 MHz. Os dados de GPR foram adquiridos no modo common offset , ao longo de 6 perfis que totalizam 1432 metros de investigação. Para a calibração da velocidade de propagação da onda eletromagnética foram executados três furos de sondagem até a profundidade de 1,8 m. Os resultados de GPR possibilitaram odelineamento preciso de refletores relacionados a interfaces geotécnicas (espessura do pavimento – revestimento de concreto e do macadame) e geológicas (areia/aterrocom entulho), mostrando a eficiência da aplicação deste método neste estudo de caso.Palavras-chave: GPR, concreto, pavimento rígido, Aeroporto Santos Dumont.

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