scholarly journals Non-destructive evaluation of moisture content in wood using ground-penetrating radar

2016 ◽  
Vol 5 (2) ◽  
pp. 575-581 ◽  
Author(s):  
Hamza Reci ◽  
Tien Chinh Maï ◽  
Zoubir Mehdi Sbartaï ◽  
Lara Pajewski ◽  
Emanuela Kiri
Keyword(s):  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Dielectric Constants ◽  
Fibre Direction ◽  
Direct Wave ◽  
Reflected Waves ◽  
Moisture Variation ◽  
Reflection Configuration ◽  
Ground Penetrating ◽  
Non Destructive

Abstract. This paper presents the results of a series of laboratory measurements, carried out to study how the ground-penetrating radar (GPR) signal is affected by moisture variation in wood material. The effects of the wood fibre direction, with respect to the polarisation of the electromagnetic field, are investigated. The relative permittivity of wood and the amplitude of the electric field received by the radar are measured for different humidity levels using the direct-wave method in wide angle radar reflection configuration, in which one GPR antenna is moved while the other is kept in a fixed position. The received signal is recorded for different separations between the transmitting and receiving antennas. Dielectric constants estimated from direct waves are compared to those estimated from reflected waves: direct and reflected waves show different behaviour when the moisture content varies, due to their different propagation paths.

scholarly journals Non-destructive evaluation of moisture content in wood by using Ground Penetrating Radar

2016 ◽  
Author(s):  
Hamza Reci ◽  
Tien Chinh Maï ◽  
Zoubir Mehdi Sbartaï ◽  
Lara Pajewski ◽  
Emanuela Kiri
Keyword(s):  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Wood Fiber ◽  
Fiber Direction ◽  
Direct Wave ◽  
Reflected Waves ◽  
Moisture Variation ◽  
Reflection Configuration ◽  
Ground Penetrating ◽  
Non Destructive

Abstract. This paper presents the results of a series of laboratory measurements carried out to study how the Ground Penetrating Radar (GPR) signal is affected by moisture variation in wood material. The effects of the wood fiber direction, with respect to the polarisation of the electromagnetic field, are investigated. The relative permittivity of wood and the amplitude of the electric field received by the radar are measured for different humidity levels, by using the direct-wave method in Wide Angle Radar Reflection configuration, where one GPR antenna is moved while the other is kept in a fixed position. The received signal is recorded for different separations between transmitting and receiving antennas. Direct waves are compared to reflected waves: it is observed that they show a different behaviour when the moisture content varies, due to their different propagation paths.

scholarly journals Effect of Moisture Content on Calculated Dielectric Properties of Asphalt Concrete Pavements from Ground-Penetrating Radar Measurements

2021 ◽  
Vol 14 (1) ◽  
pp. 34
Author(s):  
Qingqing Cao ◽  
Imad L. Al-Qadi
Keyword(s):  
Dielectric Properties ◽  
Numerical Model ◽  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Asphalt Concrete ◽  
Concrete Pavements ◽  
Proposed Model ◽  
Moisture Variation ◽  
Ground Penetrating ◽  
Non Destructive

Moisture presence in asphalt concrete (AC) pavement is a major cause of damage to the pavement. In recent decades, an increasing need exists for non-destructive detection and monitoring of the moisture content in AC pavement. This paper provides a simulated approach to quantify the effect of internal moisture content on AC pavement dielectric properties using ground-penetrating radar (GPR). A heterogeneous numerical model was developed to simulate AC pavement with internal moisture at various saturation levels. The numerical model was validated using GPR surveys on cold-in-place recycling treated pavements. An empirical formula was derived from the simulation to correlate the dielectric constant with the moisture content for non-dry AC pavement. The results validated the proposed model and, hence, demonstrated the ability of GPR to monitor moisture variation in AC pavements.

Measurement of Bulk Electrical Properties Using GPR with a Variable Reflector

2018 ◽  
Vol 23 (4) ◽  
pp. 489-496
Author(s):  
J. David Redman ◽  
A. Peter Annan ◽  
Nectaria Diamanti
Keyword(s):  
Electrical Properties ◽  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Arrival Time ◽  
Wood Chip ◽  
Direct Wave ◽  
Trace Data ◽  
Ground Penetrating ◽  
Prototype Instrument

Bulk electrical properties of media are important inherently for ground penetrating radar (GPR) applications and for providing a means to determine indirectly other physical properties such as moisture content. We have developed a reflector whose reflectivity can be controlled electronically. This variable reflector controlled by a GPR provides an effective method to measure bulk electrical properties of media. For sample measurements, the GPR is placed on one side of a sample and the variable reflector on the opposite side. GPR trace data are then acquired with the reflector in an on-state and in the off-state. By differencing these measurements, we improve the ability to detect the specific reflection event from the variable reflector. This process removes both the direct wave and clutter from the trace data, improving the quality of the refection event and our ability to accurately pick its arrival time and amplitude. We describe the variable reflector, a prototype instrument based on the reflector and numerical modeling performed to understand its response. We also show the results of testing applications to the measurement of wood chip moisture content and monitoring of the electrical properties of concrete during the curing process.

Non-Destructive Detection of Asphalt Concrete Stripping Damage using Ground Penetrating Radar

2021 ◽  
pp. 036119812110141
Author(s):  
Ye Ma ◽  
Mostafa A. Elseifi ◽  
Nirmal Dhakal ◽  
Mohammad Z. Bashar ◽  
Zhongjie Zhang
Keyword(s):  
Ground Penetrating Radar ◽  
Asphalt Concrete ◽  
Field Data ◽  
Visual Inspection ◽  
Asphalt Pavements ◽  
Reflected Waves ◽  
Ground Penetrating ◽  
The Relationship ◽  
Non Destructive ◽  
Difference Time

Ground penetrating radar (GPR) is a non-destructive evaluation technique, which has been applied to assess as-built pavement conditions and to evaluate damage and deterioration that develop over time. The objective of this study was to develop a methodology that uses GPR to detect moisture-related stripping damage in asphalt pavements. To achieve this objective, A Finite-Difference Time-Domain based simulation program was used to study the propagation of GPR signals in a stripped pavement. Field test data including GPR scans and visual inspection of cores of 202 pavement sections were used to study the relationship between GPR traces and asphalt concrete (AC) stripping damage. Based on this analysis, a novel GPR-based indicator, known as the accumulating in-layer peaks (AIP), was introduced to detect stripping damage in asphalt pavements. Field data and pavement cores were used to validate the proposed indicator and to evaluate its effectiveness in detecting the presence, extent, and severity of stripping in in-service pavement sections. Based on the results of the study, it was found that the presence of a void in the middle of the AC layer resulted in positive peaks in the reflected waves as indicated by the simulation of GPR signals. In addition, detected intermediate wave peaks between the surface and the interface between the AC and base layers on the GPR traces were associated with stripping damage in the AC layer. The AIP predicted accuracies for stripped and non-stripped sections were 80% and 96%, respectively, indicating its effectiveness in detecting stripping damage in flexible pavements.

Determination of log moisture content using ground penetrating radar (GPR). Part 1. Partial least squares (PLS) method

Holzforschung ◽  
2015 ◽  
Vol 69 (9) ◽  
pp. 1117-1123 ◽  
Author(s):  
Guillaume Hans ◽  
David Redman ◽  
Brigitte Leblon ◽  
Joseph Nader ◽  
Armand La Rocque
Keyword(s):  
Moisture Content ◽  
Least Squares ◽  
Partial Least Squares ◽  
Ground Penetrating Radar ◽  
Black Spruce ◽  
Early Time ◽  
Quaking Aspen ◽  
Pls Regression ◽  
Reflected Waves ◽  
Ground Penetrating

Abstract Ground penetrating radar (GPR) is a handheld system showing good potential for the real-time and nondestructive characterization of wood moisture content (MC). However, measurements performed over logs can be challenging because of their curved surface that can affect the GPR signal. In this study, the MC of thawed and frozen logs was estimated for three species (quaking aspen, balsam poplar, and black spruce) using the full GPR signals and the partial least squares (PLS) regression method. The signal was acquired from the cross-section (CS) and through the bark (TB) of the logs with and without an aluminum plate placed under the log. The full GPR signal does not provide better log MC prediction accuracy for small logs compared with the early-time GPR signal. The information about the shape and diameter of the log is contained in the direct and reflected waves of the GPR signal. CS models provided more accurate log MC prediction (RMSEv=7–25%) than TB models (RMSEv=6–40%) for the hardwood species. Thawed and frozen log models showed similar performances. This study demonstrates that GPR in combination with PLS regression is suitable for predicting log MC in the field.

scholarly journals Estimation of Moisture Content in Railway Subgrade by Ground Penetrating Radar

2020 ◽  
Vol 12 (18) ◽  
pp. 2912
Author(s):  
Sixin Liu ◽  
Qi Lu ◽  
Hongqing Li ◽  
Yuanxin Wang
Keyword(s):  
Moisture Content ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Geophysical Methods ◽  
Dielectric Constants ◽  
Thin Layers ◽  
Velocity Spectrum ◽  
Railway Transportation ◽  
Interval Velocities ◽  
Ground Penetrating

China is strongly dependent on railway transportation, but the frost heaving of the subgrade in cold regions has seriously affected the safety and comfort of trains. Moisture content is an essential parameter in the subgrade frost heave. Non-destructive and efficient geophysical methods have great potential in measuring the moisture content of railway subgrade. In this paper, we use the common mid-point (CMP) measurement of ground penetrating radar (GPR) to estimate the propagation velocity of electromagnetic waves in a subgrade application. We establish a synthetic model to simulate the railway subgrade structure. The synthetic CMP gathers acquired from shallow and thin layers are seriously disturbed by multiple waves and refraction waves, which make the routine velocity analysis unable to provide accurate velocities. Through the analysis of numerical simulation results, it is found that the primary reflection waves, multiple waves, and refraction waves are dominant in different offset ranges of CMP gather. Therefore, we propose a solution of the optimal gather at a certain range of offset dominated by the primary reflection wave to calculate the velocity spectrum and extract the accurate velocities for the subgrade model. The relative dielectric constants of the corresponding layers are calculated after the stacking velocities are converted into the interval velocities. Then, the moisture content is obtained by the Topp formula, which expresses the relationship between dielectric constant and moisture content. Finally, we apply the optimal gather scheme and the above interpretation process to the GPR data acquired at the railway site, and we form a long moisture content profile of the railway subgrade. Compared with the polarizability measured by the induced polarization (IP) method, it is found that the regions with high moisture content correspond to polarizability anomalies with different strengths. The comparison shows the reliability of GPR results to some extent.

scholarly journals Identifying Spatial and Temporal Variations in Concrete Bridges with Ground Penetrating Radar Attributes

2021 ◽  
Vol 13 (9) ◽  
pp. 1846
Author(s):  
Vivek Kumar ◽  
Isabel M. Morris ◽  
Santiago A. Lopez ◽  
Branko Glisic
Keyword(s):  
Compressive Strength ◽  
Ground Penetrating Radar ◽  
Material Properties ◽  
Temporal Variations ◽  
Concrete Bridges ◽  
Spatial And Temporal Variation ◽  
Reflected Waves ◽  
Ground Penetrating ◽  
Over Time

Estimating variations in material properties over space and time is essential for the purposes of structural health monitoring (SHM), mandated inspection, and insurance of civil infrastructure. Properties such as compressive strength evolve over time and are reflective of the overall condition of the aging infrastructure. Concrete structures pose an additional challenge due to the inherent spatial variability of material properties over large length scales. In recent years, nondestructive approaches such as rebound hammer and ultrasonic velocity have been used to determine the in situ material properties of concrete with a focus on the compressive strength. However, these methods require personnel expertise, careful data collection, and high investment. This paper presents a novel approach using ground penetrating radar (GPR) to estimate the variability of in situ material properties over time and space for assessment of concrete bridges. The results show that attributes (or features) of the GPR data such as raw average amplitudes can be used to identify differences in compressive strength across the deck of a concrete bridge. Attributes such as instantaneous amplitudes and intensity of reflected waves are useful in predicting the material properties such as compressive strength, porosity, and density. For compressive strength, one alternative approach of the Maturity Index (MI) was used to estimate the present values and compare with GPR estimated values. The results show that GPR attributes could be successfully used for identifying spatial and temporal variation of concrete properties. Finally, discussions are presented regarding their suitability and limitations for field applications.

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