scholarly journals Influence of Concrete Carbonation on Electromagnetic Permittivity Measured by GPR and Capacitive Techniques

2018 ◽  
Vol 23 (4) ◽  
pp. 443-456
Author(s):  
Xavier Dérobert ◽  
Géraldine Villain ◽  
Jean-Paul Balayssac
Keyword(s):  
Complex Permittivity ◽  
Ground Penetrating Radar ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Radar Signal ◽  
Reinforced Concrete Structures ◽  
Concrete Carbonation ◽  
Ground Penetrating ◽  
Non Destructive ◽  
Non Destructive Techniques

This paper addresses the effect of concrete carbonation on the propagation and dispersion of electromagnetic (EM) waves and the capability of two EM, non-destructive techniques to detect this pathology. A capacitive technique operating at low frequency (around 33 MHz) and a ground penetrating radar (GPR) with a 1.5 GHz antenna were tested for the monitoring of reinforced concrete structures. To better understand the phenomena involved in concrete carbonation, the results of two complementary experimental campaigns were analyzed for saturated concretes. First, the dispersion curves of complex permittivity were measured for both carbonated and non-carbonated samples by a cylindrical coaxial EM cell. Due to carbonation, the permittivity decreased and the level of dispersion reduced slightly. Second, using GPR (coupled at approximately 900 MHz) and capacitive measurements conducted on controlled slabs, it was confirmed that the real part of the relative permittivity decreased within a range of 2 at 33 MHz and a range of 1 to 900 MHz, while the radar signal amplitude increased.

scholarly journals Ground-penetrating-radar response to fracture-fluid salinity: Why lower frequencies are favorable for resolving salinity changes

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. J25-J30 ◽  
Author(s):  
Georgios P. Tsoflias ◽  
Matthew W. Becker
Keyword(s):  
Electrical Conductivity ◽  
Ground Penetrating Radar ◽  
Field Experiments ◽  
Fractured Rock ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Time Lapse ◽  
Fracture Aperture ◽  
Fracture Fluid ◽  
Ground Penetrating

Time-lapse ground-penetrating-radar (GPR) surveys exploit signal-amplitude changes to monitor saline tracers in fractures and to identify groundwater flow paths. However, the relationships between GPR signal amplitude, phase, and frequency with fracture aperture and fluid electrical conductivity are not well understood. We used analytical modeling, numerical simulations, and field experiments of multifrequency GPR to investigate these relationships for a millimeter-scale-aperture fracture saturated with water of varying salinity. We found that the response of lower-frequency radar signals detects changes in fluid salinity better than the response of higher-frequency signals. Increasing fluid electrical conductivity decreases low-frequency GPR signal wavelength, which improves its thin-layer resolution capability. We concluded that lower signal frequencies, such as [Formula: see text], and saline tracers of up to [Formula: see text] conductivity are preferable when using GPR to monitor flow in fractured rock. Furthermore, we found that GPR amplitude and phase responses are detectable in the field and predictable by EM theory and modeling; therefore, they can be related to fracture aperture and fluid salinity for hydrologic investigations of fractured-rock flow and transport properties.

scholarly journals Investigating the Causes of Roads Deterioration in the Form of Potholes using Non-Destructive Testing

2020 ◽  
Author(s):  
Muhammad Naveed ◽  
Kanishka S. Turrakheil ◽  
Fabio Tosti ◽  
Amir M. Alani
Keyword(s):  
Signal Processing ◽  
Ground Penetrating Radar ◽  
Radar Signal ◽  
Road Maintenance ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Material Condition ◽  
Local Roads ◽  
Ground Penetrating ◽  
Non Destructive

<p>Potholes are one of the public’s main local concerns as they cost a lot to the economy in terms of repair bills, delays while repairs are carried out and vehicle wear-and-tear. According to the Annual Local Authority Road Maintenance (ALARM) survey, eliminating the pothole backlog in England and Wales would cost £9.8bn and take a decade to complete despite increased local roads investment. The aim of this study is to research why potholes occur in the first place using non-destructive testing (NDT) and potential remedies in terms of the development of effective design and innovative materials to prevent their formation in future.</p><p>To investigate the causes of potholes formation, in-situ use of NDT methods such as ground-penetrating radar (GPR) has proven effectiveness as roads remain in continuous use. Analysis of GPR data can provide information on layer depths, material condition, moisture, voiding, reinforcement and location of other features [1, 2, 3].</p><p>Through our results, we will test two hypothesis; (i) shallow potholes are formed on loss of adhesion of the surface course, (ii) deep potholes are formed due to the loss of bearing capacity or settlement of the subgrade. Poor drainage in combination of heavy loads trigger shallow potholes while extreme wetting-drying cycles as a result of climate change decayed subgrade conditions of the pavement.</p><p>Results presented in this abstract are part of a PhD project funded by the University of West London.</p><p> </p><p><strong>References</strong></p><p>[1] Saarenketo, T. and T. Scullion (2000). Road evaluation with ground penetrating radar. Journal of Applied Geophysics (43): 119–138.</p><p>[2] Benedetto, A., Tosti, F., Bianchini Ciampoli, L., and F. D’Amico (2016). An overview of ground-penetrating radar signal processing techniques for road inspections. Signal Processing (132): 201-209.</p><p>[3] Benedetto, A., Benedetto, F., and F. Tosti (2012). GPR applications for geotechnical stability of transportation infrastructures. Nondestructive Testing and Evaluation, 27 (3): 253–262.</p>

scholarly journals Inspection of radiant heating floor applying non-destructive testing techniques: GPR and IRT

DYNA ◽  
2015 ◽  
Vol 82 (190) ◽  
pp. 221-226 ◽  
Author(s):  
Susana Lagüela Lopez ◽  
Mercedes Solla Carracelas ◽  
Lucía Díaz Vilariño ◽  
Julia Armesto González
Keyword(s):  
Infrared Thermography ◽  
Ground Penetrating Radar ◽  
Radiant Heating ◽  
Non Destructive Testing ◽  
Ceramic Tiles ◽  
Destructive Testing ◽  
Testing Techniques ◽  
Ground Penetrating ◽  
Non Destructive ◽  
Non Destructive Techniques

The inspection of radiant heating floors requires the use of non-destructive techniques, trying to minimize inspection impact, time and cost, and maximize the information acquired so that the best possible diagnosis is given. With this goal, we propose the application of infrared thermography (IRT) and ground penetrating radar (GPR) for the inspection of radiant heating floors with different floor coatings, in order to evaluate the capabilities and information acquirable with each technique. Specifically, two common floor coatings have been inspected: ceramic tiles and parquet flooring. Results show that each technique provides different information: condition of the pipelines (IRT), geometry and configuration (GPR), concluding that the optimal inspection is constituted by the combination of the two techniques.

Non-Destructive Evaluation of Reinforcing Rebar Radius by Digital Image GPR Technique

2014 ◽  
Vol 501-504 ◽  
pp. 847-851
Author(s):  
Che Way Chang ◽  
Chen Hua Lin ◽  
Shyi Lin Lee ◽  
Ping Huang Chen ◽  
Ching Cheng Jen ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
Behavior Analysis ◽  
Physical Model ◽  
Digital Image ◽  
Ground Penetrating Radar ◽  
High Efficiency ◽  
Non Destructive Evaluation ◽  
Energy Zone ◽  
Ground Penetrating ◽  
Non Destructive

Ground Penetrating Radar (GPR) is a high efficiency technology to detect the cylindrical medium in the concretes material. The electromagnetic wave is incidental to double-rebar, and measures the reflection signal behaviors from energy zone. The results from the reflection signal of electromagnetic wave of the reinforcement concretes allow evaluating the radius of double-bar (1.6cm, 1cm). A physical model can effectively measure the radius of double-bar by the result of electromagnetic wave reflex behavior analysis. The results indicate that, this techology is capable of estimating the reinforcing double-bar radius to within 6%.

Seismic reflection and ground‐penetrating radar imaging of a shallow aquifer

Geophysics ◽  
1998 ◽  
Vol 63 (4) ◽  
pp. 1310-1317 ◽  
Author(s):  
Steven J. Cardimona ◽  
William P. Clement ◽  
Katharine Kadinsky‐Cade
Keyword(s):  
Water Table ◽  
Ground Penetrating Radar ◽  
Low Frequency ◽  
Shallow Aquifer ◽  
Cone Penetrometer ◽  
Gradual Change ◽  
Cone Penetration ◽  
Geotechnical Data ◽  
Radar Images ◽  
Ground Penetrating

In 1995 and 1996, researchers associated with the US Air Force’s Phillips and Armstrong Laboratories took part in an extensive geophysical site characterization of the Groundwater Remediation Field Laboratory located at Dover Air Force Base, Dover, Delaware. This field experiment offered an opportunity to compare shallow‐reflection profiling using seismic compressional sources and low‐frequency ground‐penetrating radar to image a shallow, unconfined aquifer. The main target within the aquifer was the sand‐clay interface defining the top of the underlying aquitard at 10 to 14 m depth. Although the water table in a well near the site was 8 m deep, cone penetration geotechnical data taken across the field do not reveal a distinct water table. Instead, cone penetration tests show a gradual change in electrical properties that we interpret as a thick zone of partial saturation. Comparing the seismic and radar data and using the geotechnical data as ground truth, we have associated the deepest coherent event in both reflection data sets with the sand‐clay aquitard boundary. Cone penetrometer data show the presence of a thin lens of clays and silts at about 4 m depth in the north part of the field. This shallow clay is not imaged clearly in the low‐frequency radar profiles. However, the seismic data do image the clay lens. Cone penetrometer data detail a clear change in the soil classification related to the underlying clay aquitard at the same position where the nonintrusive geophysical measurements show a change in image character. Corresponding features in the seismic and radar images are similar along profiles from common survey lines, and results of joint interpretation are consistent with information from geotechnical data across the site.

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