• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.506-514
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• 2016

Experimental ballast track and concrete track were installed on the railway site and the frost penetration depth and the frost heave amount in the winter were measured. As a result, when the freezing index was the same, the frost penetration depth of concrete track was deeper than that of ballast track. Furthermore, when an XPS and polyethylene aggregate layer was installed below the ballast track, the frost penetration depth of the ballast track decreased significantly; in the case of the concrete track, the frost penetration depth decreased when the thickness of the subbase increased. Meanwhile, the frost heave amount also decreased when an XPS and polyethylene aggregate layer was installed below the ballast track ; in the case of the concrete track, the frost heave amount decreased when the thickness of the subbase increased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.107-113
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• 1992

This paper is the part of fundamental study considering whether the unprocessed water cooled blastfurnace slag, by-product of iron works, can be useful for some fine aggregate of mortar and concrete. The acquired results in this study show that the qualities of the water cooled blastfurnace slag produced in the state of raw material in the country in not good for using as a fine aggregate of mortar and concrete. To be used as a fine aggregate of concrete the qualities need to be improved in the process of manufacture.

• Journal of the Korean Geotechnical Society
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• v.38 no.4
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• pp.33-45
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• 2022

A series of model tests were performed in this study to demonstrate the clogging mechanism created during the installation of a compaction pile to improve soft ground. The application of an air-jet to extrude sand or aggregates from a casing during the installation of a compaction pile imposes a remarkably high-pressure difference between the composite soil layers of clay and sand (or aggregates), resulting in severe clogging. Therefore, a one-dimensional testing system was developed to simulate composite soil layers consisting of clay and sand (or aggregates) and to apply a high-pressure differential at both boundaries, thus replicating the extrusion process used in compaction pile installation. Herein, the performance of two construction materials for compaction piles of crushed stone and grading-controlled aggregates was compared. A series of one-dimensional model tests were performed under multiple pressure settings, with clogging depth and permeability measured in each case. Results indicate that, blinding clogging mechanisms and blocking defined by previous studies were observed for crushed stone, and a new mechanism of "infiltration" was revealed and defined. Whereas, the controlled aggregates performed excellently against clogging because only blinding was observed.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.79-90
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• 2004

Rutting on asphalt pavement surface is an important damage in most roadways in the world. Most of researches have developed prediction model for rutting on asphalt pavement as a function of physical properties of asphalt binder. But this study was devised to estimate rutting based on fundamental properties of asphalt mixture, not binder. Therefore this study objective is to estimate rutting based on volumetric properties, that is Air void, Void in mineral aggregate(VMA) and Void filled with asphalt(VFA), of asphalt mixture with various asphalt binders, aggregates and aggregate gradation. Results showed that it was possible to estimate rutting depth based on volumetric variables of asphalt mixture. In addition, VMA, the variable which is nor used In mix design in Korea, showed a significant correlation with rutting, It is recommended that VMA is adapted as a variable in domestic mix design. Also, It showed that VFA in the specification should be lowered at least 5% point since VFA was somewhat higher than optimum.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.565-574
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• 2008

Fire-enhanced soil hydrophobicity often increases runoff and erosion in the mountain hillslope following severe wildfires. Estimation techniques for WEPP's parameters were studied in burnt mountain slopes. In burnt mountain slopes, the model over-predicted runoff in the small runoff and under-predicted runoff in the great runoff, and in the lower sediment runoff it had a tendency to over-predict soil loss. The effective hydraulic conductivity was most sensitive in the WEPP's runoff and its sediment runoff was mainly effected by the effective hydraulic conductivity, initial saturation, rill erodibility, and interrill erodibility. To improve the applicability of the WEPP, the adjustment coefficient of effective hydraulic conductivity was defined for runoff and the adjustment coefficient of rill erodibility and interrill erodibility was presented for sediment runoff. The adjustment coefficient of effective hydraulic conductivity in wildfire mountain slopes increased with maximum rainfall intensity of single storm and the vegetation height index. The adjustment coefficients of rill erodibility depended on soil components of size distribution curve and total rainfall depths in single storm. The adjustment coefficients of interrill erodibility decreased with increases of maximum rainfall intensity and vegetation height index. These results may be used in the application of WEPP model for wildfire mountain slopes.

• Journal of the Korean Geosynthetics Society
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• v.10 no.1
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• pp.37-42
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• 2011

In this study, it is analyzed that mechanical properties and required strength of porous concrete according to the mixing ratio of cement, fine aggregate, and water/cement ratio in order to evaluate mechanical properties of porous concrete using recycled asphalt aggregate. Recycled asphalt aggregates of 13 mm were used without modification of aggregate grading to extend porous concrete application. The water/concrete ratio was poor mix and the range of compressive strength was 18.2 to 19.5 MPa. The average value of permeability showed 8.0E-02 cm/sec.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.197-205
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• 2005

This paper introduces a new method of improvement for marine soft ground, MLPP (Marine large Pack Pile). The MLPP is a reinforcement technique far the conventional SCP or GCP piles by confining them with geotextile pack. A pilot project at Busan New Port site and laboratory model tests were carried out to investigate the settlement reduction and bearing capacity enhancement effect of pack pile. The results of field and laboratory tests show that MLPP method can be a safe and economic alternative method for SCP and GCP.

• Journal of the Korea Institute of Building Construction
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• v.12 no.3
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• pp.284-290
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• 2012

Cement Fineness Modulus (CFM) is a method of expressing the distribution of particle sizes of cement in numeric form. If CFM is controlled through crush process of cement without modifying the chemical components or mineral composition of cement, it is judged to be able to produce a cement satisfying various requirements because it is estimated to enable various approaches to cement such as high early strength, moderate heat, low heat cement and so on. Therefore, in this study, as basic research for manufacturing special cement utilizing the controls of CFM, the intention was to review the impacts of CFM on the fundamental properties of concrete. To summarize the result, as mixture characteristics of fresh concrete, ratio of small aggregate and unit quantity were gradually increased, securing greater fluidity, with an increase in CFM, while the amount of AE and SP were reduced gradually. In addition, setting time was delayed as CFM increased. Furthermore, compression strength was relatively high during initial aging as CFM became smaller, but as time passed, compression strength became smaller, and it showed the same level of strength as aging time passed about three years.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5C
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• pp.211-220
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• 2012

Coarse granular materials such as gravel, rubble is used as major fill materials in earth structures of railway, road and dam. Therefore, it is essential to accurately evaluate properties of these materials for reasonable design and construction. In the precedent study, we built large triaxial testing system and verified system compliance with a focus on the dynamic properties. And we could secured the reliability of the system. In this study, the cyclic triaxial tests were performed in various experimental conditions on coarse granular material. Two series of parallel graded samples are prepared by mixing crushed rock. The influence of grain size, loading pattern, loading frequency, and fine contents were analyzed and discussed.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.51-59
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• 2021

In this study, the purpose of this study was to quantitatively grasp the specific correlation between the raw material and the occurrence of leakage by analyzing the characteristics of leakage by adjusting the type and content of the raw material constituting the asphalt mastic coating waterproofing material. To this end, two raw materials, CA (calcium carbonate) and ASE (anti-sedimentation), which are organic and mineral extender for asphalt mastic waterproofing membrane coating, were selected. viscosity and oil leakage stability (20 ℃, 40 ℃) was evaluated. As a result of the evaluation, the oil leakage stability and viscosity were inversely proportional to the CA average particle size, and it was quantitatively proven that a correlation in proportion to the ASE content was established. The results of this study are expected to be used as core data for basic mixing design in the future mixing studies to improve leakage of asphalt mastic waterproofing membrane coating.