• Journal of the Korean GEO-environmental Society
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• v.17 no.12
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• pp.45-54
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• 2016

In this study, the construction method of new underground continuos impervious wall that the bentonite slurry keeps the stability of excavated trench and the mixture of cement and bentonite plays a role as a constituent of impervious wall in the trench. The merit of homogeneity of the method so called as a cement-bentonite slurry wall enables to accurately make an estimation of hydraulic conductivity of the walls compared with that by other general grouting methods and to verify their waterproof efficiency without difficulty at the design stage. The use of cement-bentonite slurry walls for the containment of groundwater flow has also proven a cost-effective impervious wall technology by employing the simple combination of construction equipments and easy and fast construction procedures. The engineering characteristics of cement-bentonite impervious wall obtained by carrying out the laboratory experiments under various conditions. This study reveals the effect of variation of constituent materials and their mixing methods (Water-Cement-Bentonite) on the engineering characteristics of a composition. Also, this study makes some recommendations on the optimum mixing ratio and mixing sequence for the best quality at the site. That is the most important factors to estimate the construction cost and design of the technique. The comparison is lastly made to evaluate the effect of ordinary Portland and blast furnace slag cement as a bonding material on the behavior of impervious walls.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.457-464
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• 2022

In this study, XRF, Loss on ignition, SEM, and PSA analysis were performed on four types of fly ash in Vietnam and compared with fly ash in Korea. As a result, PC boiler fly ash in Vietnam has a similar chemical composition to that of PC boiler fly ash in Korea, where the content of SiO₂, Al₂O₃, and Fe₂O₃ accounts for about 70%. In addition, the result showed that blast furnace slags in Vietnam and Korea have similar quality criteria and performance. A binder material mixing test using four types of fly ash supplied from Vietnam was conducted, and the compressive strength ranged from 7.60 to 13.25 MPa after 28 days of curing. Vinh Tan fly ash showing the highest compressive strength was selected as the soil injection material for the chemical grouting method. For the formulation of the chemical grouting method, sodium silicate No.3 and silica-sol were used as liquid-A. As a result of measuring the gel time and the compressive strength of the homogel, they showed good performance satisfying the quality criteria applied in Korean construction fields. Therefore, Vinh Tan fly ash can be used as a soil injection material for the chemical grouting method.

• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.15-24
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• 2021

In Korea, which is mostly mountainous, the proportion of tunnel and underground space development are increasing. Although the ground is reinforced by applying the ground improvement method during underground space development, accidents still occur frequently in Korea. In the grouting method, a representative ground reinforcement method, the effect was judged by comparing the total amount of injection material with the amount of injection material used during the actual grouting construction. However, it is difficult to determine whether the ground reinforcement is properly performed during construction or within the target ground. In order to solve this problem, it is necessary to study a new method for quality control during or after construction by measuring electrical resistivity after performing grouting by mixing carbon fiber, which is a conductive material, and microcement, which is a grout material. In this study, as a basic study, a cement specimen mix ed with 0%, 3%, 5%, 7% of carbon fiber was prepared to evaluate the performance of the grout material mixed with carbon fiber, which is a conductive material. The prepared specimens were wet curing for 3 days, 7 days, and 28 days under 99% humidity, and then compression wave velocity and shear wave velocity were measured. As a result of the compression wave velocity and shear wave velocity measurement, it showed a tendency to increase with the increase in the compounding ratio of carbon fibers and the number of days of age, and it was confirmed that the elastic modulus and shear modulus, which are the stiffness of the material, also increased.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2001.06a
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• pp.7-7
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• 2001

다량의 점토 퇴적물로 구성된 연약지반은 대단히 큰 압축성과 낮은 강도, 높은 함수량등의 물리·역학적 특성을 갖는다. 이러한 기초지반으로서의 불리한 특성 때문에 이를 대상으로 하는 각종 토목건설공사에서는 지반개량이나 안정처리가 반드시 선행되어야 할 과제이다. 이를 위해 종래에는 샌드드레인, 페이퍼드레인 등의 물리적인 공법에 의한 지반개량이 주류를 이루었으나, 최근에는 생석회나 시멘트계 고화재를 이용한 화학적 안정 처리공법이 크게 주목을 받고 있어 이에 대한 연구가 활발한 상황이다. 본 연구는 연약 지반 안정처리에 대한 방안을 모색하기 위하여 김해 지역에 분포하는 점토 퇴적물을 대상으로 각종 광물재료를 이용한 반응실험을 통하여 반응생성물 조사와 압축강도시험 등을 행하여 그 결과를 검토하였다. 우선 연약지반의 고화에 이용 가능한 생석회, 석고, 플라이에쉬, 고분자폴리머, 시멘트 등을 사용하여 점토와 혼합한 고화실험을 행하였으며, 이에 대한 물성 및 반응생성물을 검토하였다. 이러한 각 재료를 점토에 혼합한 후 PVC관에 모울딩하여 양생시켜 실험하였다. 그 결과, 석고 및 소석회에 비하여 생석회의 경우가 비교적 큰 압축강도를 나타내고, 균열발생 빈도도 낮았다. 생석회의 경우에 Gehlenite, Hillebrandite 등의 생성물질이 검출되었다. 그러나 포틀란트 시멘트와 혼합한 경우가 강도가 가장 크게 나타났다. 반면에 고분자폴리머만 사용한 경우는 강도가 매우 낮았다. 따라서 시멘트를 일정 비율로 배합한 다른 재료를 첨가한 실험을 행하여 그 물성을 검토하였다 물질의 화학적인 특성을 고려하여 포졸란반응이 잘 일어날 수 있을 것으로 생각되는 여러 재료를 선정하여 많은 조합에 대한 실험을 행하였다. 생석회, 석고, 고령토, 규조토, 제올라이트 등의 여러 재료를 여러 조합으로 첨가하여 실험한 결과, 시멘트와 석고를 혼합한 것이 비교적으로 높은 압축강도를 나타내었다. 그리고 이러한 연구 결과를 바탕으로 연약점도의 고화에 최적인 조합과 배합비를 위한 실험을 재차 실시하였으며, 실험 후의 물성과 함께 반응생성물에 대한 검토도 행하여 그 결과를 발표하고자 한다.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.177-177
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• 2011

현재 대부분 사용되는 지하매설물용 뒤채움재는 다짐공법을 많이 사용하고 있으며, 실제로 이러한 방법은 부적절한 다짐으로 인해 침하 및 내구성 저하로 인해 파손을 초래하는 경우가 많다. 이러한 문제를 해결 할 수 있는 하나의 대안으로 유동성 뒤채움재를 이용할 수 있다. 유동성 뒤채움재는 초기 유동성, 시간에 따른 자기 강도 발현 무다짐공법 적용 등 많은 장점을 가지고 있다. 본 연구에서는 현장발생토사, 정수장슬러지 및 폐타이어분말 등 재활용 재료를 이용한 유동성 뒤채움재의 기본물성을 평가하였다. 각각의 재활용재료에 대한 입도 및 비중을 평가하였고, 최적배합설계를 결정하였으며, 모형 시험과 유한요소 해석을 위한 기본 물성값을 위해 일축압축시험, 삼축압축시험, 공진주시험 등을 수행하였다. 최적배합설계를 산정하는 과정에서 수행한 실험중 대표적인 시험으로 자가수평능력 및 자기다짐등에 필요한 유동성을 판단하는 Flow시험(ASTM D 6133) 결과 기준으로 정한 20cm이상의 값을 얻을 수 있었으며 일축압축강도의 경우 시공 후 유지 보수가 용이한 강도인 $3.0kg/cm^2{\sim}5.6kg/cm^2$이하로 설계하였으며 28일재령 일축압축강도 결과 $3.15{\sim}3.74kg/cm^2$라는 유지보수에 적당한 결과값을 나타내었다. 이 배합이 현장에서 사용이 가능하다는 것으로 판단하고 현장모형시험과 유한요소해석를 통하여 현장에서 사용하였을 때 관의 변형과 관에 작용하는 하중변화를 확인하고 현장모형시험과 유한요소해석 간의 상관관계를 규명하였다. 현장 모형 시험은 현장과 비슷하게 제작된 모형을 이용하였으며 최대한 현장과 비슷한 조건에서 뒤채움재를 타설과정 중과 타설이 완료된 상태에서 7일 양생 후 하중재하와 같이 두가지 경우에서 수직 수평토압, 관의 수직 수평변위, 관의 종단변형을 측정하였다. 유한요소해석 프로그램은 Midas GTS를 이용하여 실시하였으며 관의 변형률, 유효응력을 측정하여 규명하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.405-408
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• 2008

This study, as mock-up test for applying Polylon Fiber engineering method to the field, analyzed the fundamental characteristics and the fireproof characteristics of high strength concrete mixed with Polylon Fiber 0.05% and the results are summarized as followings. From the characteristic of the fresh concrete, both slump flow and air content were appeared to satisfy target range. And from the characteristic of hardened concrete, all compressive strengths according to the curing conditions were appeared to satisfy design standard strength of 60 MPa. From the fireproof characteristic, small scaling and spalling phenomenon were partially appeared on the surface part of specimens, but generally the excellent fireproof capacities were appeared. From the characteristic of temperature hysteresis, the highest temperature and the average temperature of reinforcing part after fire-resistant test for 3 hours were $531^{\circ}C$ and $405{\circ}C$, respectively and then satisfied fireproof standard of the Ministry of Land Transportation and Maritime Affairs.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.315-318
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• 2009

본 논문에서는 해상 기초 교각 매스 콘크리트의 수화열 저감 방안을 다루었다. 저발열 콘크리트, Mesh형 거푸집 공법 등에 대한 실험을 수행하여 각각의 수화열 저감효과를 평가하였다. 현장 실험은 사용 시멘트와 거푸집의 종류, 거푸집의 사용 면수에 따라 총 4 type으로 구성하였으며, 이에 대한 실험 결과와 유한 요소 해석 결과를 비교, 검증하여 최종적인 수화열 저감 성능을 도출하고자 하였다. 실험을 통해, 저발열 시멘트와 유로폼을 사용하는 것이 수화열 저감을 위해 효과적인 방법으로 판명되었으나 추가 공사비의 발생으로 효율성이 떨어질 것으로 판단된다. 또한 Mesh형 거푸집 적용 면 수와 온도 상승 저감 효과는 비례하는 것을 알 수 있었지만 내 외부 온도차가 다소 크게 나타나 수화열에 의한 균열 발생 확률면에서는 다소 불리하게 나타났다. 그러나 실험 단계에서 생략된 양생과 관리를 통하여 균열의 저감효과를 거둘 수 있을 것으로 판단되며, 추가적으로 거푸집 해체 단계를 생략함으로 공기단축 측면에서 유리할 것으로 판단된다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.13-14
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• 2016

This study is aimed to analyze temperature history at each section of mat foundation concrete applying double bubble sheets. The results of the study are as follows. Firstly, the results of measuring the temperature history indicate that the lowest external temperature has been recorded at -5.6℃ for the three-day measurement period. For the central section, the result indicates that the lower, center and upper part have all secured the concrete curing temperature of 18℃ or higher. This results are believed to have resulted from excellent heat insulation performance of double bubble sheets. For the edge section between the edge form and the concrete interface, the temperature has been measured, on average, approximately 12℃ lower than the central section. However, all measured sections have indicated the temperature of 5℃ or higher. Meanwhile, an analysis has been conducted through the estimation equation of compressive strength of maturity during the curing period in order to examine the possibility of early frost damage and the aspect of securing strength. It has been confirmed that the compressive strength is higher than 50°D·D, namely, 5MPa, on the 3rd day of the aging process, which allows early frost damage to be avoided.

• Journal of the Korean GEO-environmental Society
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• v.8 no.1
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• pp.27-32
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• 2007

Trafficability for construction equipments in soft ground should be secured by improving the surface course. For this situation, the ground improvement technique has been used with stiffening agent, but the improvement cement has been mostly used so far. However, oyster shell has been developed and used as the stiffening agent to expand the chance of recycling oyster shell, which is regarded as solid waste. In this research, it was confirmed mechanical characteristics of oyster shell as stiffening agent by analyzing the strength characteristic such as mixing rates, water contents, and curing days of that to the dredging soil.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.143-149
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• 2006

An experimental study was carried out to investigate the stabilizing capability of oyster shell binder, which was developed using waste oyster shell inducing environmental pollutions by piling up out at the open or the temporary reclamation. The purpose of this paper is to compare stabilinzing capability of oyster shell binder and cement binder with treated soils. For this, a series of compressive laboratory tests were peformed to evaluate strength characteristics of treated soils by both oyster shell binder and cement binder with varing water content of dredged soils, different mixing rates of binder and curing days. Based on test results, eco-friendly binder manufactured by oyster shells showed more stabilizing capacity than cement binder and is estimated as good resource materials for soft soil improvements.