• International Journal of Highway Engineering
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• v.2 no.2
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• pp.139-148
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• 2000

Currently existing Accelerated Pavement Testing (APT) systems developed in several countries have been employed mainly to test the performance of asphalt pavement. Meanwhile, the length of concrete pavement is similar to that of asphalt pavement in expressways of Korea. and is expected to increase due to its durability and compatibility to our weather condition. To meet the society's demand of having our own APT system which can examine the long-term performance of concrete pavement, a contract study to develop Korea Accelerated Loading and Environment Simulator (KALES) for concrete pavement has been performed for 3 years from 1997 through 1999. Through the project, a detailed design was Peformed for the KALES system in which the entire structure of KALES, loading mechanism, wandering mechanism, suspension system, driving system were proposed. Also in advance to design a full-scale KALES system, a sample scale model was manufactured and tested for operating motion and force distribution. It is evident that the proposed prototype KALES system will provide higher degree of traffic simulation and durable operation, based on the satisfactory fatigue analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.285-292
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• 2006

The objective of this study is to introduce the development of the first Korean full-scale APT(Accelerated Pavement Tester) and to compare the performances of general dense grade asphalt mixture and modified asphalt mixtures as the first running of the tester. The tests evaluated the rutting resistance for dense grade mixture and three different modified asphalt mixture under three different temperature conditions (25-30, 40, $50^{\circ}C$). The results of the testing were compared with the laboratory test results. Results of the tests indicated that the all the modified asphalt sections showed higher rutting resistance than the dense grade section. Especially, the difference was more noticeable at higher temperature condition. Additionally, $G^*/sin{\delta}$ is found out to be an important factor for permanent deformation prediction whereas the resilient modulus was not.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.11-20
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• 2007

This thesis develops a fatigue model for the asphalt black base using the APT(Accelerated Pavement Testing) and analyzes the correlation of the APT analysis result with results of previous laboratory tests. For the APT testing, aggregate of the maximum grain size of 25mm(BB-3) was used as the material for the asphalt black base. The result of the APT revealed that the variable of the fatigue model, i.e. the maximum tensile stress on the bottom part of the pavement, increased as the number of loading increased while the modulus of elasticity for the pavement layer decreased gradually. The tensile strain was obtained from a strain gauge, and it was used to derive the values of $k_1=1.29{\times}10^{-6}$ and $k_2=3.02$ from the basic equation of the asphalt fatigue model, $N_f=k_1(\frac{1}{\epsilon})^{k_2}$. The fatigue life predicted from the asphalt fatigue model was greater than that obtained from laboratory experiments, given the same tensile strain. Additionally, a theory to estimate the remaining life of the pavement was developed using FWD, a non-destructive experiment.

• 한국도로학회:학술대회논문집
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• 2001.10a
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• pp.23-31
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• 2001

국내 포장가속시험기의 개발은 도로신소재 개발, 중차량 교통하중의 영향분석, 온도 습도에 따른 포장체의 거동분석 등을 현장조건과 유사한 조건에서 실험 가능하게 함으로써 국내 도로분야의 연구 수준을 향상시킬 것으로 기대된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4D
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• pp.491-497
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• 2009

This paper presents the results of accelerated pavement tests (APT) that simulate permanent deformation (rutting) of asphalt concrete pavements under different temperatures and loading courses. Also, finite element (FE) analysis has been conducted to predict the test results. Test section for APT is the same as one of test sections at Korea Expressway Corporation test road and is subjected to a constant moving dual tire wheel load of APT at three different temperatures: 30, 40, $50^{\circ}C$. The moving wheel is applied at different loading courses within a 75cm wide wheel path to account for traffic wandering. Also, the effect of wandering on permanent deformation development is investigated numerically with three wandering schemes. In this study, ABAQUS is adopted to model APT pavement section with plain stain elements and creep strain rate model is used to take into account viscoplastic stain of asphalt concrete mixtures, and elastic layer properties are back-calculated from FWD measurements. Plus, the effect of boundary condition and subgrade on FE permanent deformation predictions is investigated. A full FE model that accounted for subgrade provided more realistic rut depth predictions, indicating subgrade has contributed to surface rutting.

• 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 for Agricultural Machinery Conference
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• 2003.07a
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• pp.117-121
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• 2003

다양한 형태의 작업을 수행하는 트랙터의 변속기에 대한 신뢰성을 확보하기 위해서는 장기간의 수명 시험이 요구된다. 이러한 수명 시험시간을 단축하기 위해서는 트랙터가 포장에서 이용되는 형태를 토대로 한 수명예측과 가속패턴을 작성하고 가속계수 결정하는 가속 시험법이 정립되어야 한다. (중략)

• 한국도로학회:학술대회논문집
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• 2008.10a
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• pp.111-118
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• 2008

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.211-221
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• 2001

The dynamic force estimation and strength design of KALES(Korea Accelerated Loading and Environmental Simulator) are studied. The KALES is continuously rotating the test track and subjected to the dynamic or impact forces during operation since the track is composed of straight and curved line. To estimate the dynamic equation for the model car which was already made is derived with analytical and experimental techniques. Using similarity relationships between the model car and KALES, the dynamic force and stability properties for KALES can be predicted. The stress analysis and fatigue life estimation of KALES is also estimated with the calculated dynamic load. From the stress analysis and fatigue life estimation results, it was found that the design of KALES is safe.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.809-817
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• 2008

This paper deals with the development of ViscoElastic Continuum Damage Finite Element Program (VECD-FEP++) and its verification with the results from both field and laboratory accelerated pavement tests. Damage characteristics of asphalt concrete mixture have been defined by Schapery's work potential theory, and uniaxial constant crosshead rate tests were carried out to be used for damage model implementation. VECD-FEP++ predictions were compared with strain responses (longitudinal and transverse strains) under moving wheel loads running at different constant speeds. To this end, an asphalt pavement section (A5) of Korea Expressway Corporation Test Road (KECTR) instrumented with strain gauges were loaded with a dump truck. Also, a series of accelerated pavement fatigue tests have been conducted at pavement sections surfaced with four asphalt concrete mixtures (Dense-graded, SBS, Terpolymer, CR-TB). Planar strain responses were in good agreement with field measurements at base layers, whereas strains at both surface and intermediate layers were found different from simulation results due to the complexity of tire-road contact pressures. Finally, fatigue characteristics of four asphalt mixtures were reasonably described with VECD-FEP++.