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In this study, the applications and the limitations of the Ground-penetrating radar (GPR) investigation have been addressed with the main objective of improving the efficient GPR application of subsurface surveys on Korean expressways. The depth of investigation and detection performance of anomalous objects have been studied using two different types of multichannel GPR on the Korean Expressway Corporation’s nondestructive testing testbed for subsurface detection. Based on the field survey, it was found that utilizing the plane view by depth, cross-sectional and longitudinal profile data of the multichannel GPR simultaneously, analysis and evaluation of the GPR signals are more efficient and practical. Although there was a difference in the frequency of use, the precision difference between two GPR is almost similar in the investigation depth and detection performance of the pavement subsurface anomaly. Under an asphalt concrete standard pavement section, the effective depth of cavity detection is 1–1.5 m, while detection under concrete pavement is less than 1.0 m. In addition, there is still a need to calibrate depths using field cores when constructing a 3D underground facility map.
Ji-Young Rhee; Keon-Tae Park; Jin-Woo Cho; Sang-Yum Lee. A Study of the Application and the Limitations of GPR Investigation on Underground Survey of the Korean Expressways. Remote Sensing 2021, 13, 1805 .
AMA StyleJi-Young Rhee, Keon-Tae Park, Jin-Woo Cho, Sang-Yum Lee. A Study of the Application and the Limitations of GPR Investigation on Underground Survey of the Korean Expressways. Remote Sensing. 2021; 13 (9):1805.
Chicago/Turabian StyleJi-Young Rhee; Keon-Tae Park; Jin-Woo Cho; Sang-Yum Lee. 2021. "A Study of the Application and the Limitations of GPR Investigation on Underground Survey of the Korean Expressways." Remote Sensing 13, no. 9: 1805.
This paper examined the attenuation method, which is used abroad, to derive a method to evaluate the condition of bare concrete bridge decks using ground penetrating radar (GPR) technology. For this purpose, 12 GPR surveys of 10 bridge decks in public service from the beginning of its service to 25 years of service were carried out to examine the attenuation characteristics of GPR signals under various concrete conditions. The survey revealed the signal below the top rebar of concrete bridge deck under the condition of using de-icing chlorides for snow removal was not clear. Therefore, using the receiving wave signal from top rebar was reasonable when attenuation of GPR signal was to be used for bridge deck evaluation. Examining the signal attenuation by the condition of concrete, dispersion of the attenuated signal was overall large in the initial performance period. However, since this is not due to deterioration, exclusion of the large dispersion from the evaluation of bridge deck condition was desirable. The attenuation size was linearly proportional to its two way travel time (signal transmission time), i.e., the depth of the top rebar, in a sound bridge deck. Also, the dispersion of the attenuation was small and symmetric to the linear regression line. If the bridge deck was maintained adequately, the linear regression correlation was also maintained similarly for the next several years. However, if deterioration occurred to be accompanied by increased attenuation and dispersion, correlation coefficient of the linear regression line declined. Nonetheless, the upper value of the attenuation representing sound concrete condition was still tended to be linearly proportional to two way travel time. Since the attenuation quantity could result in considerable debilitation just by the construction error, it is necessary to deal with the depth-error of top rebar for evaluating the concrete condition by using the GPR signal attenuation. Calibration was carried out by deriving a linear regression line for the signal two way travel time and the upper 90th percentile values of the attenuation obtained from the top bar position of the bridge and then removing it from the total attenuation.
Ji-Young Rhee; Jaewon Shim; Seong-Hoon Kee; Sang-Yum Lee. Different Characteristics of Radar Signal Attenuation Depending on Concrete Condition of Bare Bridge Deck. KSCE Journal of Civil Engineering 2020, 24, 2049 -2062.
AMA StyleJi-Young Rhee, Jaewon Shim, Seong-Hoon Kee, Sang-Yum Lee. Different Characteristics of Radar Signal Attenuation Depending on Concrete Condition of Bare Bridge Deck. KSCE Journal of Civil Engineering. 2020; 24 (7):2049-2062.
Chicago/Turabian StyleJi-Young Rhee; Jaewon Shim; Seong-Hoon Kee; Sang-Yum Lee. 2020. "Different Characteristics of Radar Signal Attenuation Depending on Concrete Condition of Bare Bridge Deck." KSCE Journal of Civil Engineering 24, no. 7: 2049-2062.
The main objectives of this study are to investigate the variations of the dielectric constant of concrete on Korean expressways by using a 1 GHz air-coupled Ground Penetrating Radar (GPR) system and to develop a practical approach to the condition assessment of concrete bridge decks with asphalt overlay on Korean expressways by dielectric constant measurements. A total of 684 GPR investigations of 601 actual concrete bridge decks, which are in service between 2 and 43 years, were carried out during the period between 1999 and 2013. Statistical analysis revealed that the dielectric constant of asphalt-covered concrete bridge decks reduced with service age and this trend continued until service age of over 40 years. As a result, this study provides a practical dielectric constant curve that could be used for condition evaluation of top concrete in asphalt-covered bridge decks with consideration of concrete age. Based on regression analyses of the GPR field survey data and experiences through the field survey, a double cut-off dielectric constant criterion was proposed for condition assessment of asphalt-covered concrete bridge decks on Korean expressways. In addition, a GPR field survey was performed at an actual bridge on the Yeongdong expressway in Korea to test the proposed GPR signal interpretation method. The field survey results provide fundamental data to better understand the variation of the dielectric constant of concrete in actual bridges with asphalt overlay and to develop a practical approach to condition assessment of asphalt-covered concrete bridge decks on Korean expressways by dielectric constant measurements using air-coupled GPR.
Ji-Young Rhee; Ko-Eun Park; Kang-Hyun Lee; Seong-Hoon Kee. A Practical Approach to Condition Assessment of Asphalt-Covered Concrete Bridge Decks on Korean Expressways by Dielectric Constant Measurements Using Air-Coupled GPR. Sensors 2020, 20, 2497 .
AMA StyleJi-Young Rhee, Ko-Eun Park, Kang-Hyun Lee, Seong-Hoon Kee. A Practical Approach to Condition Assessment of Asphalt-Covered Concrete Bridge Decks on Korean Expressways by Dielectric Constant Measurements Using Air-Coupled GPR. Sensors. 2020; 20 (9):2497.
Chicago/Turabian StyleJi-Young Rhee; Ko-Eun Park; Kang-Hyun Lee; Seong-Hoon Kee. 2020. "A Practical Approach to Condition Assessment of Asphalt-Covered Concrete Bridge Decks on Korean Expressways by Dielectric Constant Measurements Using Air-Coupled GPR." Sensors 20, no. 9: 2497.
Fire in a tunnel or an underground structure is characterized by a rise in temperature above 1000 °C in 5–10 min, which is due to the characteristics of the closed space. The Permanent International Association of Road Congresses has reported that serious damage can occur in an underground structure as a consequence of high temperatures of up to 1400 °C when a fire accident involving a tank lorry occurs in an underground space. In these circumstances, it is difficult to approach the scene and extinguish the fire, and the result is often casualties and damage to facilities. When a concrete structure is exposed to a high temperature, spalling or dehydration occurs. As a result, the cross section of the structure is lost, and the structural stability declines to a great extent. Furthermore, the mechanical and thermal properties of concrete are degraded by the temperature hysteresis that occurs at high temperatures. Consequently, interest in the fire safety of underground structures, including tunnels, has steadily increased. This study conducted a fire simulation to analyze the effects of a fire caused by dangerous-goods vehicles on the tunnel structure. In addition, a fire exposure test of reinforced-concrete members was conducted using the Richtlinien für die Ausstattung und den Betrieb von Straßentunneln (RABT) fire curve, which is used to simulate a tunnel fire.
Seungwon Kim; Jaewon Shim; Ji Young Rhee; Daegyun Jung; Cheolwoo Park. Temperature Distribution Characteristics of Concrete during Fire Occurrence in a Tunnel. Applied Sciences 2019, 9, 4740 .
AMA StyleSeungwon Kim, Jaewon Shim, Ji Young Rhee, Daegyun Jung, Cheolwoo Park. Temperature Distribution Characteristics of Concrete during Fire Occurrence in a Tunnel. Applied Sciences. 2019; 9 (22):4740.
Chicago/Turabian StyleSeungwon Kim; Jaewon Shim; Ji Young Rhee; Daegyun Jung; Cheolwoo Park. 2019. "Temperature Distribution Characteristics of Concrete during Fire Occurrence in a Tunnel." Applied Sciences 9, no. 22: 4740.
In this recent work, a ground penetrating radar (GPR) technique was proposed to evaluate the deteriorated depth of concrete bridge decks with asphalt overlays in the Korea expressway network. Air-coupled GPR was utilized in the measurement of the relative permittivity of concrete on bridge decks with asphalt overlays and the electromagnetic (EM) wave attenuation of the concrete cover of top reinforcing bars (rebars) in the pilot bridge in public service. In addition, 13 core samples were obtained from the bridge deck to carry out a detailed survey that includes visual inspection of the deterioration and measurement of chloride content with depth. The validity of the GPR technique was examined by comparing it with the results of the field investigation. Moreover, the correlation of the deteriorated depth with either the relative permittivity or EM wave attenuation was established. Results show that a GPR signal analysis method based on a dual-criteria (relative permittivity and EM wave attenuation) is more effective in analyzing the deterioration characteristics and evaluating the deteriorated depth of concrete bridge decks with asphalt overlay compared to the analysis method based on one of the two GPR properties. Results of the field test are considered to be significant wherein it establishes a relationship between the GPR property and deterioration characteristics of the bridge decks. Moreover, results show the practical applicability of the GPR technique in evaluating the deteriorated depth of the bridge decks with asphalt overlay.
Ji Young Rhee; Jae-Jin Choi; Seong-Hoon Kee. Evaluation of the Depth of Deteriorations in Concrete Bridge Decks with Asphalt Overlays Using Air-Coupled GPR: A Case Study from a Pilot Bridge on Korean Expressway. International Journal of Concrete Structures and Materials 2019, 13, 23 .
AMA StyleJi Young Rhee, Jae-Jin Choi, Seong-Hoon Kee. Evaluation of the Depth of Deteriorations in Concrete Bridge Decks with Asphalt Overlays Using Air-Coupled GPR: A Case Study from a Pilot Bridge on Korean Expressway. International Journal of Concrete Structures and Materials. 2019; 13 (1):23.
Chicago/Turabian StyleJi Young Rhee; Jae-Jin Choi; Seong-Hoon Kee. 2019. "Evaluation of the Depth of Deteriorations in Concrete Bridge Decks with Asphalt Overlays Using Air-Coupled GPR: A Case Study from a Pilot Bridge on Korean Expressway." International Journal of Concrete Structures and Materials 13, no. 1: 23.
The purposes of this study were to investigate the seasonal variations in the relative permittivity of actual concrete bridge decks of various ages on Korea expressways, and to propose a practical way to calibrate two critical effects, to assess the condition of the concrete bridge decks with better accuracy. For these purposes, fifty-three actual concrete bridge decks on Korea expressways were scanned using an air-coupled ground penetrating radar (GPR) system, and the relative permittivity of the concrete was evaluated from the GPR data in the field. A statistical analysis showed that the relative permittivity of the concrete bridge decks in Korea are closely correlated with seasonal changes and concrete ages. For concrete bridge decks aged 10 years or older, the effect of concrete age was not as significant as that of relative humidity of the air on relative permittivity of concrete. Based on the results, a simple calibration process was proposed to suppress the effects of seasonal variation and age of concrete on the measured relative permittivity of the concrete decks on actual bridges. As will be discussed, the resulting relative permittivity method produced better agreement with the current condition of the concrete bridge decks as determined by visual inspection and other complementary methods (energy attenuation of GPR signals and corrosion potential measurements) than without the calibration process.
Ji Young Rhee; Seong-Hoon Kee; Hong-Sam Kim; Jae-Jin Choi. Seasonal Variation and Age-related Changes in the Relative Permittivity of Concrete Bridge Decks on Korea Expressways. International Journal of Concrete Structures and Materials 2018, 12, 2 .
AMA StyleJi Young Rhee, Seong-Hoon Kee, Hong-Sam Kim, Jae-Jin Choi. Seasonal Variation and Age-related Changes in the Relative Permittivity of Concrete Bridge Decks on Korea Expressways. International Journal of Concrete Structures and Materials. 2018; 12 (1):2.
Chicago/Turabian StyleJi Young Rhee; Seong-Hoon Kee; Hong-Sam Kim; Jae-Jin Choi. 2018. "Seasonal Variation and Age-related Changes in the Relative Permittivity of Concrete Bridge Decks on Korea Expressways." International Journal of Concrete Structures and Materials 12, no. 1: 2.
One of the most serious problems in maintaining and rehabilitating bridges is the deterioration of the asphalt concrete overlay, and subsequent deterioration of the deck concrete under the overlay. Although it is important from the perspective of the road managers to evaluate the exact status of the bridge deck thorough detailed examination, it still remains a difficult problem to determine the condition of the bridge deck under the overlay without coring samples. Accordingly, it is still a common and daily practice to examine the overlay surface and bottom of the bridge deck to evaluate its condition. Instead, this study collected cores from bridges with asphalt concrete in public service, which had manifested deterioration of the concrete deck. The study aimed to delineate the relationship between the deterioration status of the concrete bridge deck and the asphalt concrete overlay, waterproof layer, cover thickness of rebar, corrosion of rebar, and chloride contents in the concrete. The results of this investigation found that the deterioration of the concrete of the bridge deck was closely related to the functionality (performance) of the waterproof layer, and the deteriorated depth was significantly related to the average chloride content in the cover concrete of the top rebar.
Ji Young Rhee; Hongsam Kim; Changkwon Ock; Jaejin Choi. An investigation of the deterioration characteristics of concrete bridge decks with asphalt concrete in Korea. KSCE Journal of Civil Engineering 2017, 22, 613 -621.
AMA StyleJi Young Rhee, Hongsam Kim, Changkwon Ock, Jaejin Choi. An investigation of the deterioration characteristics of concrete bridge decks with asphalt concrete in Korea. KSCE Journal of Civil Engineering. 2017; 22 (2):613-621.
Chicago/Turabian StyleJi Young Rhee; Hongsam Kim; Changkwon Ock; Jaejin Choi. 2017. "An investigation of the deterioration characteristics of concrete bridge decks with asphalt concrete in Korea." KSCE Journal of Civil Engineering 22, no. 2: 613-621.