• Title/Summary/Keyword: Soil cement

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Stabilizing Capability of Oyster Shell Binder for Soft Ground Treatment (표층/심층혼합처리용 굴패각 고화재의 고화성능 평가)

  • Yoon, Gil-Lim;Kim, Byung-Tak
    • 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.

Reduction Characteristics of Hexavalent Chromium in Cement/Fe(II) Systems

  • 강희석;서진권;황인성;박주양
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2002.04a
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    • pp.233-236
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    • 2002
  • 다양한 산업활동에 의하여 발생하는 6가 크롬 (Cr(Ⅵ))은 대표적인 토양 및 지하수 오염물질이다. Cr(Ⅵ)은 3가크롬(Cr(III))로의 환원에 의한 침전반응으로 이동성이 저하된다고 알려져 있다. 본 연구에서는 기존의 고형화/안정화 공정에 환원.분해 반응을 추가한 2가철 기반 분해성 고형화/안정화(Degradative Solidification/Stabilization)공정에 의한 Cr(Ⅵ) 처리 특성을 고찰하였다. 회분식 실험결과 cemen/Fe(II) system내에 Cr(Ⅵ)은 환원반응 뿐만 아니라 cement에 의한 침전에 의해서도 제거됨이 밝혀졌다. Cr(Ⅵ)의 제거속도는 Fe(II)의 반응당량에 비례하는 것으로 보여진 반면, cement/solution ratio에 따른 Cr(Ⅵ) 제거동역학의 차이는 그다지 크지 않았다

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Study of initial setting for solidification process of dredged soil of rural stream (농촌 소하천 고함수비 퇴적 저지의 고화처리에 대한 초기응결연구)

  • Chang, Pyung-Wuck;Woo, Chull-Woong;Kim, Seong-Pil;Kim, Jae-Hyung
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2002.10a
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    • pp.345-348
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    • 2002
  • The dredged soils of rural streams can be treated with cement for recycling. It is very important to know whether the treated soils have achieved some required qualities for further treatments if the soils are mixed with cement. In this study, fall-cone test was used to examine changes in workability and compactibility during an curing time of soil-cement mixture. Test results showed that fall-cone apparatus can be satisfactorily used for this purpose. Although there was some difference of initial curing time and cement contents, the engineering properties of treated soils were little affected.

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Effect of cement stabilization on geotechnical properties of sandy soils

  • Shooshpasha, Issa;Shirvani, Reza Alijani
    • Geomechanics and Engineering
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    • v.8 no.1
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    • pp.17-31
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    • 2015
  • An experimental program was performed to study the effects of cement stabilization on the geotechnical characteristics of sandy soils. Stabilizing agent included lime Portland cement, and was added in percentages of 2.5, 5 and 7.5% by dry weight of the soils. An analysis of the mechanical behavior of the soil is performed from the interpretation of results from unconfined compression tests and direct shear tests. Cylindrical and cube samples were prepared at optimum moisture content and maximum dry unit weight for unconfined compression and direct shear tests, respectively. Samples were cured for 7, 14 and 28 days after which they were tested. Based on the experimental investigations, the utilization of cemented specimens increased strength parameters, reduced displacement at failure, and changed soil behavior to a noticeable brittle behavior.

Variations of Density and Strength for Reinforced Soil Mixture by Long-Tern Dry Shrinkage (장기적 건조수축에 의한 보강혼합토의 밀도 및 강도 변화)

  • 이상호;차현주;장병욱;박영곤
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1999.10c
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    • pp.239-244
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    • 1999
  • In this study , the variation of dry density and unconfined compressive strength were investigated, calcium carbonate, quicklime, portland cement, 19mm monofilaments and fibrilllated fibers were used as reinforcement materials. And calcium chloride was added to cement and calcium carbonate reinforced soil mixture in order to accelerate setting and hardening speed. It appears that dry density is highest in calcium carbonate reinforced soil mixture with 9% of mixing rae. According to increasing the amount of fibers, in soil mixture , the dry density decreased. The more the amount of monofilament fibers is the higher the compressive strength. But the compressive strength is decreased in fibrrillated fiber added soil mixture with more than 1.0% of mixing rate.

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Numerical Modeling of Soil-Cement based on Discrete Element Method (개별요소법을 이용한 시멘트 혼합토의 수치모델링)

  • Jeong, Sang-Guk
    • Journal of the Korean Geosynthetics Society
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    • v.15 no.4
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    • pp.33-42
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    • 2016
  • Discrete Element Method was conducted for rock and coarse-grained materials in development of granular mechanics and related numerical model due to analyze and apply micromechanical property. And it was verified that the analysis to consider bonding effect was insufficient. In this study, to overcome limits of existing method, it was conducted to analyze difference between indoor test result and bonding effect using $PFC^{3D)}$. For indoor test of mixed soil, uniaxial compression tests by curing time and by cement content were performed. And, DEM to suitable for each condition of indoor test was conducted. In the result of this study, in terms of geotechnics, it was verified that DEM can be used for application as numerical laboratory as well as prediction of micro and macro behavior about bonding effect of mixed soil.

Unhardening Phenomena of SCW constructed in Organic Soil (가설 토류벽용 SCW의 미경화 현상)

  • 김교원;송정락;강기영
    • The Journal of Engineering Geology
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    • v.1 no.1
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    • pp.11-18
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    • 1991
  • A series of laboratory tests were conducted to verify the unhardening phenomena of Soil-Cement Wall (SCW) and the results are presented in this paper. Specimens are prepared by mixing the site soil with cement and additives at a various ratio. The hydration of the cement mixed with the in-situ soil was retarded due to the higher organic content of the soil. In order to remove the influence of the organic matters in hydration reaction, calcium chloride (CaCI$_2$) was added as an acceleration additive at a different ratio. The optimum ratio of the calcium chloride for the higher SCW strength was determined as 2% of cement weight. The strength, however, was decreased by adding 4 and 6% of the additives. The effect of other additives, NaOH and NaSiO$_2$, were also investigated and the results are included. The strength of SCW by adding sodium hydroxide was lowered. And the short term strength by adding sodium silicate was increased but the long term strength was decreased.

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An Experimental Study on the Optimum Mix Design and Site Application Case of Soil Mixing Wall for Trench Stability (구벽안정성을 위한 SMW 최적배합비 및 현장적용 사례에 관한 연구)

  • Kwon, Yeong-Ho
    • Journal of the Korea Concrete Institute
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    • v.27 no.4
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    • pp.419-426
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    • 2015
  • The purpose of this study is to investigate experimentally the optimum mix design and site application case of soil mixing wall (SMW) method which is cost-effective technique for construction of walls for cutoff wall and excavation support as well as for ground improvement before constructing LNG storage tank typed under-ground. Considering native soil condition in site, main materials are selected ordinary portland cement, bentonite as a binder slurry and also it is applied $1,833kg/m^3$ as an unit volume weight of native soil, Variations for soil mixing wall are as followings ; (1) water-cement ratio 4cases (2) mixing velocity (rpm) 3levels (3) bleeding capacity and ratio, compressive strength in laboratory and site application test. As test results, bleeding capacity and ratio are decreased in case of decreasing water-cement ratio and increasing mixing velocity. Required compressive strength (1.5 MPa) considering safety factors in site is satisfied with the range of water-cement ratio 150% below, and test results of core strength are higher than those of specimen strength in the range of 8~23% by actual application of element members including outside and inside in site construction work. Therefore, optimum mix design of soil mixing wall is proposed in the range of unit cement $280kg/m^3$, unit bentonite $10kg/m^3$, water-cement ratio 150% and mixing velocity 90rpm and test results of site application case are satisfied with the required properties.

A Study on the Frictional Resistance Chracteristics of Pressurized Soil Nailing Using Rapid Setting Cement (초속경 시멘트를 사용한 가압식 쏘일네일링의 주입시간에 따른 마찰저항특성에 관한 연구)

  • Lee, Arum;Shin, Eunchul;Lee, Chulhee;Rim, Yongkwan
    • Journal of the Korean Geosynthetics Society
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    • v.17 no.4
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    • pp.1-10
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    • 2018
  • Although the soil nailing method is generally used as a gravity grouting, the development and application of pressurized grouting method has recently increased to address the problem of joint generation and filling due to grouting. Pressurized grouting of the soil nailing method is generally used in combination with ordinary portland cement and water. In the field, the cement is mixed with the rapid setting cement to reduce curing time because ordinary portland cement takes more than 10 days to satisfy the required strength. In this study, uniaxial compression tests and laboratory tests were carried out to confirm the efficiency of the grouting material according to the mixing ratio of rapid setting cement. The mixing ratio of 30% grouting satisfies the required strength within 7 days and satisfies the optimum gel time. As a result of the laboratory test with granite weathered soil, the reinforcing effect was confirmed to be 1.5 times as compared with the gravity type at an injection time of 10 seconds and a strain of 15%. The friction resistance increases linearly with the increase of the injection time, but it is confirmed that the friction resistance decreases due to the hydraulic fracturing effect at the injection time exceeding the limit injection pressure. Numerical analysis was performed to compare the stability of slopes not reinforced with slopes reinforced with gravity and pressurized soil nailing.

Stabilization of oily contaminated clay soils using new materials: Micro and macro structural investigation

  • Ghiyas, Seyed Mohsen Roshan;Bagheripour, Mohammad Hosein
    • Geomechanics and Engineering
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    • v.20 no.3
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    • pp.207-220
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    • 2020
  • Clay soils have a big potential to become contaminated with the oil derivatives because they cover a vast area of the earth. The oil derivatives diffusion in the soil lead to soil contamination and changes the physical and mechanical properties of the soil specially clay soils. Soil stabilization by using new material is very important for geotechnical engineers in order to improve the engineering properties of the soil. The main subjects of this research are a- to investigate the effect of the cement and epoxy resin mixtures on the stabilization and on the mechanical parameters as well as the microstructural properties of clay soils contaminated with gasoline and kerosene, b- study on the phenomenon of clay concrete development. Practical engineering indexes such as Unconfined Compressive Strength (UCS), elastic modulus, toughness, elastic and plastic strains are all obtained during the course of experiments and are used to determine the optimum amount of additives (cement and epoxy resin) to reach a practical stabilization method. Microstructural tests were also conducted on the specimens to study the changes in the nature and texture of the soil. Results obtained indicated that by adding epoxy resin to the contaminated soil specimens, the strength and deformational properties are increased from 100 to 1500 times as that of original soils. Further, the UCS of some stabilized specimens reached 40 MPa which exceeded the strength of normal concrete. It is interesting to note that, in contrast to the normal concrete, the strength and deformational properties of such stabilized specimens (including UCS, toughness and strain at failure) are simultaneously increased which further indicate on suitability and applicability of the current stabilization method. It was also observed that increasing cement additive to the soil has negligible effect on the contaminated soils stabilized by epoxy resin. In addition, the epoxy resin showed a very good and satisfactory workability for the weakest and the most sensitive soils contaminated with oil derivatives.