• Korean Journal of Environmental Agriculture
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• v.29 no.1
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• pp.47-53
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• 2010

The purpose of this study was to investigate the effectiveness of a stabilization treatment for As contaminated soil. A combination of hydrated lime, Portland cement, $FeCl_3{\cdot}6H_2O$, and NaOH were used as stabilizing agents. The effectiveness of stabilization treatment was evaluated by the Korean Standard Test (KST) method (1N HCl extraction). Sequential extractions were performed to investigate the As distribution after treatment. Following the application of the treatment, curing periods of up to 7 and 28days were investigated. The experimental results showed that a combination of hydrated lime/Portland cement was more effective than treatments of hydrated lime or Portland cement at immobilizing As in the contaminated soil. The treatment of 25wt% hydrated lime and 5wt% Portland cement was effective in reducing As leachability less than the Korean warning standard of 20 mg/kg. However, the treatments of hydrated lime and Portland cement failed to meet the Korean warning standard even when up to 30 wt% was used. The treatment utilizing hydrated lime and $FeCl_3{\cdot}6H_2O$ was not effective in properly reducing As leachability. The addition of $FeCl_3{\cdot}6H_2O$ was negative in terms of pH condition. Moreover, the treatment with hydrated lime/NaOH was effective in reducing As leachability but not as much as hydrated lime/Portland cement. The sequential extraction results indicated that the residual phase was greatly increased upon the treatment of hydrated lime/Portland cement. It was concluded that the hydrated lime/Portland cement treatment was the best among the other combinations studied at achieving trace As concentrations.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.657-664
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• 2000

Weak and soft compressible clay deposits are commonly found in natural subgrade soils. These Soils need to be stabilized for using the subbase materials of highway constructions. This paper presents that a chemical treatment using chemical additives comprised of sulfate(SO$_4$) and chloride(Cl) is evaluated for stabilizing soft clay deposits and lime. The physical and mechanical characteristics of soil-lime and additives are described by means of a laboratory study. The study results indicate that the presence of chlorides encouraged the efficiency of lime stabilization, and the use of calcium chloride with quicklime is the best additive for improving soil behavior. The treated soil with lime-calcium chloride can have the adaptability to the subbase materials of highway constructions.

• Geomechanics and Engineering
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• v.18 no.5
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• pp.471-480
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• 2019

The constructions of engineering structures such as airports, highways and railway on clayey soils may create many problems. The economic losses and damages caused by these soils have led researchers to do many studies using different chemical additives for the stabilization of them. Lime is a popular additive used to stabilize the clayey soils. When the base course is stabilized by mixing with an additive, inevitable delays may occur during compaction due to reasons like insufficient workers, breakdown of compaction equipment, etc. The main purpose of this study is to research the effect of compaction delay time (7 days) on the strength, compaction, and dynamic properties of a clay soil stabilized with lime content of 0, 3, 6, 9, 12 and 15% by dry weight of soil. Compaction characteristics of these mixes were determined immediately after mixing, and after 7 days from the end of mixing process. Within this context, unconfined compressive strength (UCS) under the various curing periods (uncured, 7 and 28 days) and dynamic triaxial tests were performed on the compacted specimens. The results of UCS and dynamic triaxial tests showed that delayed compaction on the strength of the lime-stabilized clay soil were significantly effective. Especially with the lime content of 9%, the increase in the shear modulus (G) and UCS of 28 days curing were more prominent after 7 days mellowing period. Because of the complex forms of hysteresis loops caused by the lime additive, the damping ratio (D) values differed from the trends presented in the literature and showed a scattered relationship.

• Journal of Environmental Science International
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• v.26 no.8
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• pp.955-966
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• 2017

Amendment of multi-binders was employed for the immobilization of metal(loid)s in field-contaminated soils to reduce the leaching potential. The effect of different types of multi-binders (lime/diammonium phosphate, diammonium phosphate/ladle slag and lime/ladle slag) on the solidification/stabilization of metal(loid)s (Pb, Zn, Cu and As) from the smelter soil and mine tailing soil were investigated. The amended soils were evaluated by measuring Toxicity Characterization Leaching Procedure (TCLP) leaching concentration of metal(loid)s. The results show that the leaching concentration of metal(loid)s decreased with the immobilization using multi-binders. In terms of TCLP extraction, the mixed binder was effective in the order of lime/ladle slag > diammonium phosphate/ladle slag > lime/diammonium phosphate. When the mixed binder amendment (0.15 g lime+0.15 g ladle slag for 1g smelter soil and 0.05 g lime+0.1 g ladle slag for 1 g mine tailing soil, respectively) was used, the leaching concentration of metal(loid)s decreased by 90%. However, As leaching concentration increased with diammonium phosphate/lime and diammonium phosphate/ladle slag amendment competitive anion exchange between arsenic ion and phosphate ion from diammonium phosphate. The Standard, Measurements and Testing programme (SM&T) analysis indicated that fraction 1 (F1, exchangeable fraction) decreased, while fraction 4 (F4, residual fraction) increased. The increased immobilization efficiency was attributed to the increase in the F4 of the SM&T extraction. From this work, it was possible to suggest that both arsenic and heavy metals can be simultaneously immobilized by the amendment of multi-binder such as lime/ladle slag.

• Journal of Soil and Groundwater Environment
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• v.20 no.7
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• pp.135-147
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• 2015

Remediation of metal(loid)s-contaminated sites is crucial to protect human and ecosystem. Solidification and stabilization of metal(loid)s by the binder amendment is one of the cost-effective technologies. In this study, metal (loid)s in various field-contaminated soils obtained from steel-making, metal refinery and mining tillage were immobilized by the application of single binders such as diammonium phosphate (DAP), lime, and ladle slag. The efficiency of solidification and stabilization was evaluated by Toxicity Characteristic Leaching Procedure (TCLP) and the Standard, Measurements and Testing programme of European Union (SM&T) extraction processes. In terms of TCLP extraction, the binder was effective in order of lime > DAP > ladle slag. All binders were highly effective in the immobilization of Pb, Zn, Cu, Ni, and Cd. The increased immobilization efficiency is attributed to the increase in the Step III and IV fractions of the SM&T extraction. Lime and ladle slag were highly effective in the immobilization of the metal(loid)s, however, As release increased with DAP due to competition between the phosphate originated from DAP and arsenate. A further study is needed for the better immobilization of multi metal(loid)s using binary binders.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1052-1062
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• 2011

Residual of heavy metals originated from abandoned metal mines in agricultural field can cause adverse effect on ecosystem and eventually on human health. For this reason, remediation of heavy metal contaminated agriculture field is a critical issue. In this study, five different amendments, agriculture lime, dolomite, steel slag, zeolite, and compost, were evaluated for stabilization efficiency of heavy metals in agricultural field. Applied mixing ratio of amendments was varied (2% or 6%) depending on properties of amendments. Result showed that soil pH was increased compared to control (6.1-6.7) after mixing with amendments and ordered as dolomite (7.2~8.3) > steel slag (6.7~8.1) > agriculture lime (6.6~7.4) > zeolite (6.2~6.9) > compost (6.1~7.1). Among other amendments, agriculture lime, steel slag, and dolomite showed the highest stabilization efficiency of heavy metals in soil. For Cd, stabilization efficiency was 49~72%, 51~83%, and 0~36% for agriculture lime, steel slag, and dolomite respectively. In case of Pb, 43~64, 37~73%, and 51~73% of stabilization efficiency was observed for agriculture lime, steel slag, and dolomite respectively. However, minimal effect of heavy metal stabilization was observed for zeolite and compost. Based on result of this study, amendments that can increase the soil pH were the most efficient to stabilize heavy metal residuals and can be adapted for remediation purpose in agricultural field.

• Geomechanics and Engineering
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• v.15 no.6
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• pp.1219-1225
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• 2018

In this study, a comprehensive laboratory experimental programme was conducted on expansive soil with a high swelling potential to study the influence of different additive materials on swelling pressure and index properties. Lime, sand, multifilament fiber and fibrillated fiber were used for stabilization of expansive soil. Lime, sand and fibers were respectively added to the expansive soil at 0-7%, 0-80%, 0-0.5%. On each mixture that was prepared by the proportions mentioned above, Atterberg limits, compaction, and swelling pressure tests were conducted. From the result of these experiments, the swelling pressure-time relation could be replaced by a rectangular hyperbola established to facilitate the prediction of ultimate percent swelling with a few initial data points. The best type of additive and its optimum ratio for engineering purposes could be estimated rapidly by this approach.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.505-512
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• 1999

Soft marine clay deposits pose several foundation problems. Generally, lime stabilization is used worldwide for solidifying of soft marine clay deposits. In this paper, a series of laboratory tests were conducted to verify clay-lime reaction. A clay was collected from Pusan, which was mixed with various quantities of quick lime and slaked lime. Various compounds produced by clay-lime reaction were identified by X-ray diffraction analysis. The physico-chemical properties of the clay were also investigated. Compounds such as calcium silicate hydrate (CSH), calcium aluminate hydrate (CAH), calcium aluminate (CA), hillebrandite, and gehlenite were identified. It is likely that such compounds were mainly produced by pozzolanic reaction. Based on the change of physico-chemical properties obtained by the reaction, the water content was considerably decreased when lime was added to the clay. In addition, unconfined strength was increased. In the other hand, quick lime was more effective than slaked lime in decreasing and increasing of the water content and unconfined strength, respectively. Fewer cracks were produced when the clay was mixed with quick lime. It is suggested that these beneficial changes produced by the mixing of the clay and lime depend on the properties of compounds obtained by chemical reaction.

• 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.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.20-23
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• 2005

The objective of this study is to examine a stabilized efficiency of heavy metals including Cd, Cu, Pb and Zn using slaked lime. Tailings from the Janggun Pb-Zn mine, the second Yeonhwa Pb-Zn mine, the Jisi Au-Ag mine and the Sangdong W mine were sampled and measured heavy metal concentrations contents using AAS as various extraction methods. During 156 hours, column test were undertaken to evaluate the possibility of stabilization by slaked lime. The result shows that $Ca(OH)_2$ has a good efficiency in heavy metal stabilization, especially at the Jisi mine with stabilized efficiencies of 97%(Cd), 99%(Cu), 86%(Pb) and 99%(Zn), respectively.