• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.239-250
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• 1993

The dynamic resilient modulus tests to determine the $M_R$ of the soils require expensive equipments and well trained personnels to obtain reliable test results. These problems inherent in the dynamic resilient modulus testing have been realized as major negative factors to hinder the $M_R$ test from being practically implemented as a routine test. In this regard. it is highly desirable to develop a simpler alternative testing method incorporating inexpensive equipments and easy-to-perform testing procedures. Developed in this study is an alternative $M_R$ test method based on statically repeated loading scheme utilizing the standard static triaxial test equipments. Applicability and limitations of the developed static $M_R$ testing method are investigated for typical subgrade soils in Korea.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.158-167
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• 2008

The quality control of compacted fills has been carried out by evaluating relative densities and coefficients of soil reaction. These measures have several limitations regarding repeatability and reliability of field measurements, and difficulties to use in the fills including large grain size as gravels and boulders. Also, the density is not directly related to the design parameter such as resilient modulus. A preliminary investigation for the usage of the stiffness as a control measure has been carried out. In the laboratory, the stiffness (P-wave velocity) was measured during compaction tests. The stiffness at the optimal moisture content was proposed to use a target control parameter likewise maximum dry density. A field method to match the target stiffness was also proposed by considering easiness of the method and availability of equipment. The most phenomenal feature of the method is that the control parameter (stiffness) is closely related to resilient modulus and can be consistently used from the design stage to the field control during construction.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.1-9
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• 2016

PURPOSES : The performance properties (indirect tensile strength, rutting resistance, and resilient modulus) of recycled aged CRM mixtures and their correlation with Superpave binder properties (viscosity, high failure temperature, $G^*sin{\delta}$, and stiffness) were investigated. METHODS: A series of Superpave binder tests was performed by using a rotational viscometer, DSR, and BBR to evaluate the performance properties. In addition, the CRM mixes were artificially aged through accelerated aging processes, and their properties were evaluated. The correlation between the properties of recycled aged CRM binders and the engineering properties of recycled aged CRM mixtures was experimentally determined. RESULTS : The rut depth values decreased and the ITS values increased with increasing high failure temperature. In general, the resilient modulus properties seemed to be poorly correlated with the high-temperature values, regardless of the aggregate source. CONCLUSIONS: The recycled aged CRM binders and mixtures can lead to satisfactory performance, and the properties of these binders are strongly correlated with the engineering properties of the mixtures.

• International Journal of Railway
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• v.6 no.3
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• pp.112-119
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• 2013

A mid-size RC test apparatus (MRCA) equipped with a program is developed that can test samples up to D=10 cm diameter and H=20 cm height which are larger than usual samples used in practice. Using the developed RC test apparatus, two types of crushed trackbed foundation materials were tested in order to get the shear modulus reduction curves of the materials with changing of shear strain levels. For comparison purpose, large repetitive triaxial compression tests (LRT) with samples of height H=60cm and diameter D=30 cm were performed also. Resilient modulus obtained from the LRT was converted to shear modulus by considering elastic theory and strain level conversion and were compared to shear modulus values from the MRCA. It is found from this study that the MRCA can be used to test the trackbed foundation materials properly. It is found also that strain levels of $E_{v2}$ mostly used in the field should be verified considering the shear modulus reduction curves and proper values of $E_{v2}$ of trackbed foundation must be used considering the strain level verified.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.113-116
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• 2007

This is a research for evaluated recycled glass powder to add asphalt concrete filler. To make a comparative study, Mechanical performance of lime stone and slag dust Mixtures was evaluated according to test procedure. Lab. performance tests included marshall stability, indirect tensile strength, resilient modulus and wheel tracking. Water resistance tests were evaluated by marshall strength ratio and tensile strength ratio. In conclusion, Results of mechanical performance showed that recycled glass powder mixtures were equivalent to conventional mixtures. Especially, result of tensile strength ratio tested recycled glass powder mixtures was superior to conventional mixtures.

• Journal of the Korean GEO-environmental Society
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• v.14 no.8
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• pp.53-60
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• 2013

The compaction control method of national road substructure is using field density test to determine the relative compaction and plate bearing test to check the load bearing capacity. However, these two tests digitize a construction site manager's judgment based on his experience, so mechanical basis is weak. Resilient modulus method, which is recently being used to resolve such problem, is evaluated as a rational design method of pavement structure that can rationally reflect the stress-strain state of pavement materials that is caused by the condition of load repetition of vehicle load. However, the method of measuring the resilient modulus is difficult and lengthy, and it has many problems. To replace it, light falling weight test is recently being proposed as a simple test method. Therefore, this research uses dynamic plate loading test, which quickly and simply measures the elastic modulus of the subgrade and sub-base construction and site of maintenance, to judge the possibility of compaction control of the stratum under the road, and it proposes relation formula by analyzing the result of static load test.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.149-157
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• 2001

The purpose of this study was to investigate the property of a new Korean stainless steel wire(Jinsung Ind.) comparing with other foreign Products. Five types of stainless steel wires (Standard, Resilient, HI-T of Unitek, Stainless steel of Ormco and Jinsung Ind.) in 0.016x0.022 and 0.019x0.02 were tested to observe for Composition analysis, size difference, tensile properties, flexure bending property, tortion property, surface hardness and surface topography by means of SEM. The findings suggest that: 1. In maximum tensile strength of tensile properties, Unitek Hi-T showed the greatest value, followed by Unitek Resilient, Jinsung Stainless Steel, Ormco Stainless Steel, Unitek Standard in 0.016x0.022, and Unitek Hi-T showed highest value, followed by Jinsung Stainless Steel, Ormco Stainless Steel, Unitek Resilient, Unitek Standard in 0.019x 0.025. 2. In elongation rate, Unitek Standard showed the greatest value, fellowed by Ormco Stainless Steel, Unitek Hi-T, Unitek Resilient, Jinsung Stainless Steel in 0.016x0.022, and Unitek Hi-T showed the highest value, followed by Unitek Standard, Ormco Stainless Steel, Jinsung Stainless Steel, Unitek Resilient in 0.019x0.025. 3. In modulus of elasticity, Jinsung Stainless Steel showed the greatest value, followed by Unitek Hi-T, Unitek Resilient, Ormco Stainless Steel, Unitek Standard in 0.016x0.022, and Unitek Resilient showed the highest value followed by Jinsung Stainless Steel, Ormco Stainless Steel, Unitek Hi-T, Unitek Standard in 0.019x0.025. 4. In bending fatigue test, Jinsung Stainless Steel showed the greatest fracture resistance, followed by Unitek Hi-T, Unitek Standard, Unitek Resilient, Ormco Stainless Steel in 0.016x0.022, and Unitek Hi-T showed the greatest fracture resistance followed by Jinsung Stainless Steel, Unitek Resilient, Unitek Standard, Ormco Stainless Steel in 0.019x0.025. 5. In twist test, Unitek Resilient showed the greatest fracture resistance, followed by Jinsung Stainless Steel, Unitek Hi-7, Ormco Stainless Steel, Unitek Standard in 0.016x0.022, and Jinsung showed the greatest fracture resistance, followed by Unitek Resilient, Unitek Standard, Ormco Stainless Steel, Unitek Hi-T. 6. In surface topography, every products showed indentation and pitting. Jinsung stainless steel wire showed long thin indentation and relatively smooth surface. Unitek wires showed indentation and pitting and Ormco wire showed a lot of irregular pittings.

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.57-68
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• 2008

The stabilization techniques in the pavement foundations have advantages in increasing pavement performance and reducing pavement thickness. By mixing the geomaterials and stabilizer, the economical and structurally sound layer can be added in the pavement system. Until now, these techniques have been applied in the field empirically and the design criteria for stabilization has not been established. The purposes of this paper are to evaluate the mechanistic properties of stabilizers used for geomaterials and determine the type and optimum amount of stabilizer for each technique. The unconfined compressive testing and repeated load resilient modulus test were conducted on the coarse grained soils mixed with various types of stabilizer to investigate the strength and deformation characteristics of stabilized geomaterials. It is found from the test that the unconfined compressive strength of stabilized geomaterials is more than ten times higher than that of gradation modified geomaterials. The resilient modulus of stabilized geomaterials increases by $6{\times}10$ times compared to the original soils and tends to increase with increase of volumetric and deviatoric stress, and amount of stabilizer.

• Journal of the Korean GEO-environmental Society
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• v.14 no.7
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• pp.51-56
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• 2013

Recently, a top record of hourly-based rainfall has been changed annually and flood damages of road have increased. To solve this problem, pavements for drainage were developed and practically constructed but there was no considerations on sub-base. In this research, we proposed standard for distribution of particle size of sub-base to consider strength characteristic and drainage property. We focused to compare coefficients strength and permeability by laboratory tests. Prior to tests, 4 samples were selected under the consideration on the international or domestic design guideline. In the tests, strength characteristics were compared with resilient modulus. Also, permeability characteristics were compared with coefficient of upward and downward permeability. Resilient modulus was determined with MR test using cyclic triaxial testing system. Two permeability tests were carried out. One is variable head permeability test for downward drainage and the other is Rowe Cell test for upward drainage. In the case of Rowe Cell test, middle-sized sampler with 150mm diameter was used for this study. Consequentially, we tried to find the optimum distribution of particle size to satisfy both of strength and permeability characteristics for sub-base.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.165-175
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• 2009

With the current move towards adopting mechanistic-empirical concepts in the design of pavement structures, state-of-the-art mechanistic analysis methodologies are needed to determine accurate pavement responses, such as stress, strain, and deformation. Previous laboratory studies of pavement foundation geomaterials, i.e., unbound granular materials used in base/subbase layers and fine-grained soils of a prepared subgrade, have shown that the resilient responses followed by nonlinear, stress-dependent behavior under repeated wheel loading. This nonlinear behavior is commonly characterized by stress-dependent resilient modulus material models that need to be incorporated into finite element (FE) based mechanistic pavement analysis methods to predict more realistically predict pavement responses for a mechanistic pavement analysis. Developed user material subroutine using aforementioned resilient model with nonlinear solution technique and convergence scheme with proven performance were successfully employed in general-purpose FE program, ABAQUS. This numerical analysis was investigated in predicted critical responses and domain selection with specific mesh generation was implemented to evaluate better prediction of pavement responses. Results obtained from both axisymmetric and three-dimensional (3D) nonlinear FE analyses were compared and remarkable findings were described for nonlinear FE analysis. The UMAT subroutine performance was also validated with the instrumented full scale pavement test section study results from the Federal Aviation Administration's National Airport Pavement Test Facility (FAA's NAPTF).