• International Journal of Highway Engineering
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• v.7 no.2 s.24
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• pp.1-12
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• 2005

This study was conducted to evaluate effect of geogrid and fabric, which are used underneath the overlaid asphalt pavement for retarding reflection cracking by simulated laboratory test. In this study, an interlayer at the interface between old concrete pavement surface and overlaid asphalt mixture, and polymer-modifier were used as an effort of retarding reflection crack initiation and for strengthening mixture. Five products were used in preparation of asphalt concrete beam specimen which was tack coated on top of jointed concrete block. Simulated Mode I and II fracture test were conducted under wheel loading and results were compared among those products. From the test results, several material and reinforcement combinations were observed to have a significant retardation effect against reflection cracking. The most effectively strengthened pavement against reflection cracking was found to be the LDPE-modifier asphalt mixture with a grid reinforcement at the bottom.

• Journal of the Korean Geotechnical Society
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• v.32 no.4
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• pp.51-61
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• 2016

In this study, a new TDR system equipped with a flat type probe has been developed to improve the currently used TDR system that measures dry density and water content. To verify the developed TDR system, TDR tests were conducted on Jumunjin sand and three typical soils. Also, additional tests were performed to measure the correction value of the developed probe. Using the TDR signals, dielectric constant, electrical conductivity and soil constants were derived. The water content and dry density of the soils were determined through the TDR tests. The applicability of the TDR system was examined by comparison of the measured values by TDR and the real values. The values of dry density and water content were found to have about 2% and 0.5% error, respectively. Based on the test results, it has been confirmed that the new TDR system can be used as an alternative to the previous TDR system as it can measure the dry density and the water content with reasonable accuracy, leading to significant time and cost savings.

• Journal of the Korean Geotechnical Society
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• v.27 no.5
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• pp.61-74
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• 2011

This is a fundamental research on use as fill material of lightweight waste such as bottom ash and tire shred. We carried out the test for particle size distribution, specific gravity, density, shear strength, permeability and vertical compression settlement, considering water content change and temperature effect of several waste materials. Bottom ash, which is lighter than soils, has similar permeability and particle size distribution to those of weathered soils. But permeability may differ depending on the particle size distribution. The shear strength aspect of bottom ash and tire shred mixed materials are similar to that of natural fill materials. In the 1-D vertical compression settlement test, we could be assured that bottom ash and tire shred mixed materials showed similar compression settlement to that of sand under actual vertical stress. Furthermore, materials including bottom ash showed smaller compression settlement than that of weathered soils in the long-term settlement test under wetting and freezing-thawing condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1178-1187
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• 2008

Quality assurance for embankment compaction is one of very important procedures to guarantee high quality construction. However, only sand replacement method (KS F2312) and static plate load test (KS F2310) which are conventional and tiresome methods are used to evaluate degree of compaction at construction fields. Recently, new types of devices such as the geogauge and the light falling weight deflectometer (LFWD), the soil impact hammer (CASPFOL) and dynamic cone penetration test etc. which are able to substitute for the conventional methods are begun to use to evaluate soil stiffness. In this study, a laboratory model test was performed to evaluate correlations among test results obtained from the new devices and to assess the potential use of them. All test results have correlations with relative density and water content. Especially, the coefficients of correlation between $E_G$ from the geogauge and $K_{30'}$ from the soil impact hammer and between $E_G$ from the geogauge and $E_{LFWD}$ from LFWD are more than 0.7 but those between the results from DCP and others are less than those between $E_{G{\cdot}}$ and $K_{30'}$ and $E_G$ and $E_{LFWD}$.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.573-576
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• 2008

Recently, it is the well-known that there are some kinds of problem the waste concrete generated while repairing, reinforcing and dismantling of structures in the domestic and overseas. In this paper, various tests were performed about the use of the recycled concrete fine aggregate for the materials of high quality and structural concrete. And also, in order to improve structural performance of the concrete structure the steel frame was under overcrowded arrangement of steel bar. Consequently, it was be necessary the Self-Consolidating Concrete(SCC) that can fill the concrete into the work-form corner which has become overcrowded arrangement of steel bar without any other vibration. The purpose of this study is related to the properties of Self-Consolidating Concrete(SCC) according to mixing ratio of recycled concrete fine aggregate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1C
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• pp.1-6
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• 2012

In this study, field tests were performed to evaluate the stability of pre-insulated pipe during the compaction operation and to recommend an alternative backfill material. Three types of natural sand (fine-grained and medium-grained, coarse-grained sand), crushed sand and two types of gravel (10 mm, 20 mm) were used as backfill material in the field tests. Field tests were performed to determine the behavior (earth-pressure and deformation, installation damage) of the pre-insulated pipe due to variation of different types of backfill material. Based on the evaluation and comparison of field test results, it was determined that crushed sand is the most suitable back-fill material that can be used as an alternative for medium grained sand for pre-insulated pipes with respect to the engineering behavior and material supply.

• Geotechnical Engineering
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• v.12 no.5
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• pp.103-116
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• 1996

Man-made vibrations from traffic and construction activities are important because they may cause damage to structures. The current literature provides that damages in the urban areas were not caused by direct transmission of vibration, but rather through subsequent settlement caused by soil densification. In this paper. prediction technique of ground borne vibration induced settlement was introduced on the basis of case studies. In situ application technique of the settlement prediction model developed in laboratary was described, and the predicted settlement was compared with the measured settlement from case studies. The settlement from case studies hlatched well with the settlement calculated from the model. The parametric studies of settlement in typical urban site conditions were performed to determine the sensitive parameters and to develop reliable vibration monitoring and interpretation schemes. These demonstrated the potential usefulness of the model for the evaluation and prediction of the vibration induced in-situ settlement of sands.

• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.31-41
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• 2013

The dredged soils of western sea of Korea have been used as the fill materials because it possess the characteristics that constitute silt, silty sand and sand mainly. However, a study on dredged soils as the fill materials is insufficient. Hence, in this present study, the application the dredged soils of western sea of Korea as the fill materials was confirmed. Primary, the composition characteristics of the ground was analyzed to confirm the application on dredged soils as the fill materials by the piezo-cone penetration test. In laboratory test, it was performed the self-weight consolidation test for mechanical characteristics of the dredged soils. The direct shear test using self-weight consolidation test sample for shear strength characteristics was performed after self-weight consolidation test. Additionally, the mechanical characteristics of the dredged soils on elapsed time using self-weight consolidation test sample, which is drained naturally, was evaluated. The dredged soils of western sea of Korea show that unit weight and shear strength is increased as natural drain time elapses.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.115-121
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• 2010

To evaluate the engineering characteristics of aggregate base materials, cyclic triaxial, CBR and permeability tests were performed for 15 samples. The CBR values of aggregate base materials have wide range from 32 to 110(average 81) and the amount of swelling in submerged conditions has below 0.04mm. The Modulus of aggregate base materials were significantly affected by volumetric stress, linear volumetric model was best for fitting. The modulus of aggregate base materials were determined within range of 100MPa~600MPa, 80~270 and 0.1~0.6 for model coefficient $k_1$ and $k_2$ respectively. The empirical correlation model was suggested that prediction the modulus from the basic properties obtained from particle size distribution test and compaction test. The coefficient of determination of the proposed correlation model was 0.423 for model coefficient $k_1$, 0.920 for model coefficient $k_2$ and 0.872 for modulus with stress level.

• Journal of the Korean Geotechnical Society
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• v.33 no.10
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• pp.49-58
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• 2017

Grouting for soil improvement has generally been applied to the depth over water table. Recently, it is needed to develop the grouting technique for soils under greater static water pressure or greater overburden pressure in constructions such as deep excavation or harbour deepening. In this study, a laboratory apparatus was developed to control the injection pressure, load pressure, and hydrostatic pressure. A series of experiments were performed with various degrees of hydrostatic pressure using the developed equipment. As a result, injected volume increase as injection pressure increase, while the volume significantly decreased under hydrostatic pressure. Larger volume of grout bulb was shown in soils with larger granular and pore size based on the comparison result of volume changes with respect to the amount of grouting injection.