Ground penetrating radar wave attenuation models for estimation of moisture and chloride content in concrete slab

2016 ◽  
Vol 106 ◽  
pp. 659-669 ◽  
Author(s):  
S.F. Senin ◽  
R. Hamid
Keyword(s):  
Ground Penetrating Radar ◽  
Wave Attenuation ◽  
Concrete Slab ◽  
Chloride Content ◽  
Attenuation Models ◽  
Ground Penetrating ◽  
Radar Wave

Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar

2009 ◽  
Vol 40 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Nils Granlund ◽  
Angela Lundberg ◽  
James Feiccabrino ◽  
David Gustafsson
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Laboratory Test ◽  
Liquid Water ◽  
Ground Penetrating Radar ◽  
Wave Attenuation ◽  
Radar Measurements ◽  
Ground Penetrating ◽  
Radar Wave ◽  
The Relationship

Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1 m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.

Effect of Moisture and Chloride Content on the Direct and Reflected Ground Penetrating Radar Waves Amplitude Ratio in Concrete Slab

2015 ◽  
Vol 74 (3) ◽  
Author(s):  
Syahrul Fithry Senin ◽  
Roszilah Hamid
Keyword(s):  
Linear Relationship ◽  
Ground Penetrating Radar ◽  
Amplitude Ratio ◽  
Concrete Slab ◽  
Chloride Content ◽  
Peak Amplitude ◽  
Reflected Waves ◽  
Time Domain Signal ◽  
Content Variation ◽  
Ground Penetrating

This paper focused on the effect of various moisture and chloride content on the direct and reflected waves (DW and RW) of Ground Penetrating Radar (GPR) amplitude ratio of concrete slab. The GPR is used in detecting both corrosion agents of 13 numbers of concrete (water/cement ratio= 0.7) slab samples. Radar measurement is employed on a fixed point of the samples to measure two signals referred to as the direct and reflected radar waves amplitudes. Simple signal processing on the collected time domain signal plots is executed by MATLAB® software to compute the attenuation of peak-to-peak amplitude of DW and RW which are normalized with respect to the peak-to-peak amplitude of DW recorded in air. From the analysis, strong linear relationships (R2 = 0.82 and 0.96) for water content variation of DW and RW are found. However, a very weak linear relationship with R2 of 0.31 for chloride content variation of DW but a strong linear relationship (R2 = 0.95) for the RW are established. These findings showed that both moisture and chloride content have a measurable influence on both GPR signals, which enable the GPR utitilisation on detecting the amount of both corrosion agents in concrete. The DW and RW amplitude ratio have the potential usage in mapping problematic zone by moisture and chloride contamination in concrete.

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.

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.

scholarly journals High-resolution hydrothermal structure of Hansbreen, Spitsbergen, mapped by ground-penetrating radar

1999 ◽  
Vol 45 (151) ◽  
pp. 524-532 ◽  
Author(s):  
J.C. Moore ◽  
A. Pälli ◽  
F. Ludwig ◽  
H. Blatter ◽  
J. Jania ◽  
...  
Keyword(s):  
High Resolution ◽  
Ground Penetrating Radar ◽  
Water Levels ◽  
Large Water ◽  
Complex Temperature ◽  
Polythermal Glacier ◽  
Ground Penetrating ◽  
Isolated Point ◽  
Radar Wave ◽  
Water Contents

AbstractDetailed ground-penetrating radar (GPR) surveys at 50 and 200 MHz on Hansbreen, a polythermal glacier in southern Svalbard, are presented and interpreted. Comparison of the variations in character of the radar reflections with borehole thermometry and water levels in moulins suggests that GPR can be used to study the hydrothermal properties of the glacier. The high resolution of the GPR data shows that the hydrothermal structure of the glacier is highly variable both along the centre line and on transverse profiles. Water contents for many places and depths within the glacier were calculated by estimating radar-wave velocities to point reflectors. We find typical water contents of 1-2% for the temperate ice, but wetter ice associated with surface crevassing and moulins (typically 4% water content). There is evidence that wet ice sometimes overlays drier ice. The hydrothermal structure is thus shown to be very complex. Temperature gradients in the cold ice indicate freezing rates of temperate ice below cold ice of 0.1-0.5 ma-1, while isolated point reflectors within the cold ice indicate large water-filled bodies that are probably related to the regular drainage structure of the glacier.

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.

Determining Bridge Deck Chloride Quantities Using Ground Penetrating Radar

2021 ◽  
Author(s):  
Anthony Alongi
Keyword(s):  
Ground Penetrating Radar ◽  
Bridge Deck ◽  
Bridge Decks ◽  
Cost Effective ◽  
Chloride Content ◽  
Signal Propagation ◽  
Radar Signal ◽  
Signal Loss ◽  
Deicing Salts ◽  
Ground Penetrating

<p>Chlorides from deicing salts attack the steel reinforcement in bridge decks which can ultimately cause delamination and deterioration of the concrete. For transportation agencies, the repair cost from these defects are estimated to exceed $5B per year in USA and make up between 50% - 85% of bridge maintenance budgets. While, the removal and replacement of chloride contaminated concrete is the most long-lasting and cost-effective remediation, few methods exist to determine chloride content in bridge decks. This research describes an entirely new method for determining chloride quantity in bridge decks using ground penetrating radar (GPR) technology and establishes and quantifies the relationship between chlorides in concrete (which cause corrosion of reinforcing steel and delamination of concrete) and the effect on GPR signal propagation. Specifically, it shows that there is a deterministic relationship between radar signal attenuation and the amount of chloride and moisture in bridge deck concrete, and that when moisture content is known it is possible to estimate chloride quantity based on signal loss or attenuation measurements. Our research also demonstrates the practical application of this concept by utilizing GPR along with limited coring (three or more core samples) and laboratory chloride measurements to produce an accurate and quantitative, spatial mapping of chlorides in bridge decks.</p>

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