• International Journal of Highway Engineering
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• v.1 no.2
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• pp.155-168
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• 1999

Asphalt pavement tends to rut in high temperature and to crack in cold temperature. The performance of asphalt pavement can be deteriorated by korean weather condition which has the four distinct seasons. In this study, the typical sections that may minimize rutting and fatigue were analyzed through the numerical model tests. The layered elastic theory , finite element method and visco elastic theory were utilized for these numerical model tests. From the various numerical model tests, it is found that an optimum design procedure was recommended. It was increasing the thickness of asphalt stabilized base with fixing the wearing course as 5cm the minimum specified thickness. The section was most beneficial in resting rutting and fatigue. From the analysis of the relative index on tensile strain and cost analysis, it was recommended that the thickness ratio of subbase and asphalt concrete is 1.0$\sim$2.5.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.85-92
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• 1996

The Measurement method of the plastic strain ratio is various in Automotive sheet steel. In this paper, the measurement of the plastic strain are used two different methods, ASTM E 517 method and the automatic strain measurement tensile specimen during the tensile test, and compared the plastic strain ratios from the two methods. The experimental results showed that the measured plastic strain ratios from the automatic strain measurement method are coincide with that from the ASTM E 517 standard measurement in various specimens. Therefore, automatic strain measurement method by two extensometers shows good accuracy. Also, the strain dependance of plastic strain ratios could be recorded by the computer continuously and anisotropy of the strength coefficient, K, and strain hardening exponent, n ,could be compared with each direction automatically through the use of automatic strain measurement system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.146-152
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• 2018

In this study, to improve the performance of asphalt mixtures for plastic deformation occurring mainly in Korea, complex modifiers were prepared by mixing powders and liquid type modifiers. The main constituents were powdery diatomaceous earth, mica and carbon black, and liquid type solid 70% SBR latex. The tensile strength ratios for the two asphalt mixtures used in the test were above 0.80 for the Ministry of Land Transportation (2017) asphalt mixture production and construction guidelines. The effects of increasing the tensile strength in the dry state was more than 14% when the composite modifier was added. The deformation rate per minute by the wheel tracking test load was an average of 0.07 to 0.147 for each mixture. The strain rate per minute was improved by the modifier, and the dynamic stability was improved by almost 100% from 295 to 590. In addition, the final settling was reduced from 11.38 mm to 9.57 mm. A plastic deformation test using the triaxial compression test showed that the amount of deformation entering the plastic deformation failure zone at the end of the second stage section and in the third stage plastic deformation section was 1.76 mm for the conventional mixture and 1.50 mm for the complex modifier mixture. The average slope of the complex modifier asphalt mixture mixed with the multi-functional modifier was 0.005 mm/sec. The plastic deformation rate is relatively small in the section where the road pavement exhibits stable common performance, i.e. the traffic load.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.79-89
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• 2008

The pavement performance model is the most important factor to determine the pavement life in the mechanistic-empirical pavement design guide (MEPDG). As part of Korean Pavement Research Program (KPRP), the Korean Pavement Design Guide (KPDG) is currently being developed based on mechanistic-empirical principle. In this paper, the rutting prediction model of asphalt mixtures, one of the pavement performance model, has been developed using triaxial repeated loading testing data. This test was conducted on various types of asphalt mixtures for investigating the rutting characteristics by varying with the temperature and air void. The calibration process was made for the coefficients of rutting prediction model using the accelerated pavement testing data. The accuracy of prediction model can be increased when by considering the effect of individual rutting properties of materials rather than shear stresses with depths.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.151-155
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• 2006

Elastic-viscoplastic structural analysis is performed for regenerative cooling chamber of liquid rocket thrust chamber using Bodner-Partom visco-plastic model. Strain rate test was also conducted for a copper alloy at various temperatures in order to get material constants of visco-plastic model used in the structural analysis. Material constants of visco-plastic model were obtained from strain rate test results and visco-plsstic model was incorporated into finite element program, Marc, by means of user subroutine. The structural analysis results indicate that the deformation of cooling channel is mostly caused by thermal loading rather than pressure loading and confirmed structural stability of the cooling channel under operating condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.4028-4032
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• 2013

Recycling method for pyrolyzed carbon black from pyrolysis process of waste tires is needed. Carbon black from pyrolysis of waste tires was used to modify and improve the permanent deformation properties of asphalt binder. 0%, 5%, 10%, 15% and 20% of pyrolyzed carbon black was mixed. Couple of laboratory tests, such as softening point, flash point test, rotational viscometer test and dynamic shear rheometer test, were carried out. The use of pyrolyzed carbon black incresed the softening point, rotational viscosity at 135oC, and resistance of permanent deformation.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.4
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• pp.388-392
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• 2012

This study proposes a fully non-contact measurement method to assess acoustic nonlinearity of narrowband surface waves generated by a line-arrayed laser beam by using a laser-ultrasonic detector in the way of two-wave mixing (TWM) method. This method was applied to figure out a relationship between plastic deformation and nonlinearity characteristics of a plastically deformed aluminum specimens. The experimental results showed that the acoustic nonlinearity of the laser-generated surface wave increased proportionally to the level of tensile deformation. This tendency is in good agreement with the result of measurement by contact method with PZT-transducer.

• Journal of the Korean Geosynthetics Society
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• v.2 no.3
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• pp.39-46
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• 2003

The major pavement distress types found in the domestic roadways include rutting, fatigue cracking, and reflection cracking which are results of the environment and repeated traffic loads. These distresses usually occur before pavements approach their design life, and therefore, a significant amount of national budget is spent for maintenance of roadway pavements. The purpose of this study is to establish a geosynthetics-asphalt pavement system. For the study, wheel tracking tests are conducted to analyze the controlling effect of geosynthetics on rutting of asphalt pavement. On the basis of these works, the reinforcement effect of geosynthetics on the rutting of the asphalt pavement is clarified and deformation characteristics of geosynthetics-asphalt mixture is examined.

• Journal of the Society of Disaster Information
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• v.8 no.2
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• pp.100-107
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• 2012

The main purpose of this research is to propose advanced bridge-decks surfacing from the examples of In-Cheon bridge with Guss asphalt and Gyul-Hyeon bridge with stone matrix asphalt(SMA) concrete. The research results presented that the Guss asphalt concrete pavement was weak when rutting was developed due to the low resistance at high temperatures. The SMA concrete pavement demonstrated good resistance to plastic deformations and was easy to maintain pavement conditions. The results mentioned above are generalized in developed counties where surfacing pavement techniques for steel bridge-decks are advanced. However, due to the lack of construction experiences in Korea, appropriate construction guidelines and organized research for the steel bridge deck pavements are necessary for more advanced steel bridge decks surfacing.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.17-28
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• 1999

In order to analyze effects of strain rate on consolidation of natural clay, this paper presents a nonlinear elasto viscoplastic model in which viscoplastic behavior is modeled by a unique effective stress-strain-strain rate relationship (equation omitted). The predicted values using numerical analysis are compared with measured ones in several laboratory tests such as creep test, multistage load test, and relaxation test for Berthierville clay. It is possible to estimate consolidation behavior of natural clay with reasonable accuracy using the proposed nonlinear viscoplastic model.