• Title/Summary/Keyword: Ground solidification material

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A Fundamental Properties of Microcement in Earth Concreting (지반보강용 마이크로시멘트의 기초적 특성)

  • 김진춘;최광일;박재용
    • Proceedings of the Korea Concrete Institute Conference
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    • 1994.10a
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    • pp.217-222
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    • 1994
  • Generally speaking, grouting on the base stabilizes the ground as the aspects of mechanic and engineering properties, with drilling hole at any depth of the earth, and pressuring the cement milk or special chemical grouting material in it. The purpose of grouting on the base is waterproofness and solidification of the ground by earth concreting that the cement milk pass through paticles of soil or crack of rock. This report shows the fundamental properties of microcement compared with those of ordinary portland cement in a point of grouting. It also describes that experimental applications on the treatment of the weathered rock at the constructior of Taegu subway and Boryong earth filled dam site, south of chungchung province, resulted in success.

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The influence of mechanical damage on the formation of the structural defects on the silicon surface during oxidation (규소 결정 표면의 구조 결함의 형성에 미치는 기계적 손상의 영향)

  • Kim, Dae-Il;Kim, Jong-Bum;Kim, Young-Kwan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.15 no.2
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    • pp.45-50
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    • 2005
  • During oxidation process, several type of defects are formed on the surface of the silicon crystal which was damaged mechanically before oxidation. As the size of abrasive particle increases multiple dislocation loops are produced favorably over oxidation-induced stacking faults, which are dominantly produced when ground with finer abrasive particle. These defects are not related with the crystal growth process like Czochralski or directional solidification. During directional solidification process, twins and stacking faults are the two major defects observed in the bulk of the silicon crystal. On the other hand, slip dislocations produced by the thermal stress are not observed. Thus, not only in single crystalline silicon crystal but also in multi-crystalline silicon, extrinsic gettering process with programmed production of surface defects might be highly applicable to silicon wafers for purification.

Determination of Solidified Material's Optimum Mixing Ratio for Reservoir Embankment Reinforcement (저수지 제체 보강을 위한 고화재 최적 배합비 결정)

  • Jaegeun Woo;Jungsoon Hwang;Seungwook Kim;Seungcheol Baek
    • Journal of the Korean GEO-environmental Society
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    • v.25 no.6
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    • pp.5-12
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    • 2024
  • Currently, a grouting method that minimizes damage to the reservoir embankment by injecting solidification agent at low pressure is commonly used to ensure waterproofing and safety of the embankment, but the use of solidification agents can cause issues, such as a decrease in durability and a lack of clear method for determining the mixing ratio. In this study, when the base ground and solidification agent were stirred and mixed at various weight mixing ratios, the permeability coefficient and strength of the mixture were confirmed through laboratory tests, and the optimal mixing ratio was suggested through analysis of the test results. The specimen for the laboratory test was produced considering the mixing ratio of the solidification agent. The specimen for the permeability coefficient test was tested by producing one each of cohesionless and cohesive soil for a mixing amount of 1.5 kN/m3 of solidification agent, and the permeability test results confirmed that the water barrier performance was secured below the permeability coefficient value required by various design criteria. A total of 24 specimens for the strength test were produced, 3 for each of 5 mixing amounts for cohesive soil and 3 mixing amounts for cohesionless soil. The strength test results showed that the uniaxial compressive strength tends to increase linearly with increasing curing time for both cohesionless soil and cohesive soil when the mixing amount is less than 2.0 kN/m3. Therefore, the optimal mixing ratio applied to the site is determined to be mixing amount of 1.5 kN/m3 and 2.0 kN/m3. Finally, numerical analysis reflecting test results was conducted on design case for improvement projects for aging reservoirs embankment to verify the water barrier performance and safety improvement effects.

A Hardening Properties of Eco-Friendly SCW Grouting Material (친환경 SCW공법용 그라우팅재의 경화특성)

  • Jo, Jung-Kyu;Park, In-Wook;Mun, Kyung-Ju;Hyung, Won-Gil
    • Journal of the Korea Institute of Building Construction
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    • v.18 no.2
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    • pp.109-115
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    • 2018
  • Since the current method of SCW cement milk pouring method uses one to one ratio of cement milk with OPC, there are some problems such as drying shrinkage, increased cost, difficulty of controlling mix proportions for various conditions of applied soil, and precipitation of $Cr^{6+}$ due to the excessively used cement. Specifically, in aspect of sustainability issues of cement manufacturing, the consumption of cement should be reduced. Hence, in this research, as a replacement of cement for SCW method, blast furnace slag with sulfate or alkali as a stimulant, and expansive admixture were used. By using blast furnace slag as a hardening composite of SCW, there are many advantages such as free controllable mix proportions, rapid setting time with less mud occurrence, less cost with less energy for mixing, constant strength development, and less precipitation of $Cr^{6+}$. Regarding the alternative composites for SCW, in this research, durability and chloride resistance were evaluated.

The Injection Characteristics and Environmental Effects for Grouting Materials Based on Cement (시멘트계 주입재 종류별 주입 특성 및 환경적 영향 연구)

  • 천병식;이재영;서덕동
    • Journal of the Korean Geotechnical Society
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    • v.19 no.2
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    • pp.159-170
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    • 2003
  • In this study, the mixed design of grout with hish strength.high permeation.high durability and environmental stability as the state of the art in material field was performed. Also, the subjects of grouting, grouting effects for ground conditions, and environmental effects were analyzed. According to these results, the fundamental data will be suggested as a design of grouting in the field application. The physical, mechanical and chemical characteristics with particle shape of the grouts were analyzed. Then, the gel-time of grouts, which is essential for workability and permeation range, were controlled. Also, the laboratory model grouting tests were performed to find the characteristics of solidification, permeation and durability with grouts. The ordinary portland, slag and microcement which have been used in the construction field were evaluated fur the environmental effects. To find the leaching of $Cr^{6+}$characteristics in cement grouts, $Cr^{6+}$ leaching tests were performed for the raw materials. Also, the results of leaching test were shorn by surrounding environment. Then, the unconfined compression strength tests were performed with the homo-gel samples, and the amount of changed $Cr^{6+}$ was measured by curing solution.

Study on Solidification and Strength of Soft Soils by Using Waste Magnesia-Carbon Powder (폐 Magnesia-Carbon Powder를 이용한 연약지반 고형화 및 강도 증진에 대한연구)

  • Choi, Hun;Song, Myong Shin;Kang, Hyung Ju;Jung, Eui Dam;Kim, Ju Seng
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.1
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    • pp.35-40
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    • 2011
  • Magnesia-carbon brick is used to refractory material in Converter and/or Ladle furnace for molten steel manufacturing. The rapid growth of steel making industry, molten steel industry is increased. Therefore, growth of molten steel industry lead to make waste magnesia-carbon brick by repair of Converter and/or Ladle furnace. These waste magnesia-carbon brick is abandoned all. Besides, as it is loosely composed of silt and clay including sand falling according to the type of gangue, rainwater inflows and outflows relatively easily, but silt or clay particles absorb water for a long period, weakening ground. This study tried to show that when colluvial soil is solidified using waste magnesia-carbon brick powder as a way to solidify strengthen the rigidity of colluvial soil.

A Study on the Utilization Method in the SCW Method using Supplementary Cementitious Materials (시멘트 대체재료를 활용한 SCW공법에서의 활용 방안에 대한 연구)

  • Kwang-Wu Lee;Jae-Hyun Park;Young-Won Lee;Dae-Sung Cho
    • Journal of the Korean Geosynthetics Society
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    • v.22 no.3
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    • pp.87-95
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    • 2023
  • Recently, redevelopment of the original downtown area is underway, the necessity of construction in adjacent location is increasing. However, excavations in dense urban areas are prone to ground problems due to various causes, so it is necessary to use materials and methods that can minimize such problems. As a general earth retaining method, various methods such as diaphragm wall and CIP method are applied using cement. However, since a large amount of cement is used for the installation of earth retaining method, it is necessary to conduct research on the development of new cement substitute materials to significantly reduce greenhouse gas emissions. In this study, we utilized the hardening reaction of blast furnace slag powder, desulfurized gypsum and high calcium fly ash by alkali activation and applied it to the SCW method. As a result, it was analyzed that the compressive strength of solidified soil using development solidification material was 96.2 ~ 106.3% of OPC at 28 days of curing. In addition, the strength increment ratio was 2.06 for sandy soil and 2.41 for clayey soil, which was higher than 1.85 of OPC. It seems an advantageous in terms of long-term strength. In addition, from the environmental point of view, it was analyzed that there is no elution of heavy metals and that greenhouse gas emissions can be dramatically reduced. Therefore, if further studies are conducted, it can be applied to the SCW method.

Effect of Limestone Fineness on Physical Properties and Environmental Impact of Cement (석회석의 분말도가 시멘트의 물리적 특성 및 환경에 미치는 영향)

  • In-Gyu Kang;Jin-Man Kim;Sang-Chul Shin;Geon-Woo Kim;Tae-Yun An
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.12 no.1
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    • pp.82-93
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    • 2024
  • Since the cement industry generates more than 60 % of CO2 during the clinker production process, supplementary cementitious materials are used worldwide to reduce CO2 efficiently. Mainly used supplementary cementitious materials such as blast furnace slag and fly ash, which are used in various industries including the cement industry, concrete admixtures, and ground solidification materials. However, since their availability is expected to decrease in the future according to the carbon neutrality strategy of each industry, new supplementary cementitious materials should be used to achieve the cement industry's goal for increasing the additive content of Portland cement. Limestone is a material that already has a large amount in the cement industry and has the advantage of high grinding efficiency, so overseas developed countries established Portland limestone cement standards and succeeded in commercialization. This study was an experimental study conducted to evaluate the possibility of utilizing domestic PLC, the effect of fineness and replacement ratio on the physical properties of cement was investigated, and the environmental impact of cement was evaluated by analyzing CO2 emissions.