• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.35-44
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• 2021

This research studies the stabilization method for improved soil sloped through the on-site application of Paper Flyash ground stabilizers. The target strength required for improved soil is 500 kPa, and the compressive strength for the slope surface needs to be less than 1,000 kPa after the improvement in order to plant vegetation. To meet this condition, we mixed soil from the site and the ground stabilization material, which is the main material for surface improvement material, performed mixing design and conducted various tests including strength test, permeability test and plantation test. After analyzing the results of the compression test on improved soil slope, we proposed soil constants for the improved soil. In order to evaluate the applicability of the improved soil on the slope, the site construction was carried out on the collapsed slope and the reinforcement evaluation of the surface of the improvement soil was conducted. The stability was not secured before the reinforcement, but the test shows after the reinforcement with improved soil, the safety rate is secured up to 48 hours during the raining period. In addition, the compressive strength of the improved soil at the site was secured at more than 200 kPa adhesion as planned, and the soil hardness test result was also found to be within the specified value of 18-23 mm, which increased the resistance to rainfall and ability to grow plant on the surface for improved soil.

• Geomechanics and Engineering
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• v.15 no.4
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• pp.1005-1016
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• 2018

This paper presents an investigation on the properties of two types of cement kiln dust (CKD)-stabilized dredged sediments, silt and clay with a comparison to hydrated lime stabilization. Unconfined compressive strength (UCS) and California bearing ratio (CBR) tests were conducted to examine the optimal stabilizer content and classify the type of highway material. A strength development model of treated dredged sediments was performed. The influences of various stabilizer types and sediment types on UCS were interpreted with the aid of microstructural observations, including X-ray diffraction and scanning electron microscopy analysis. The results of the tests revealed that 6% of lime by dry weight can be suggested as optimal content for the improvement of clay and silt as selected materials. For CKD-stabilized sediment as soil cement subbase material, the use of 8% CKD was suggested as optimal content for clay, whereas 6% CKD was recommended for silt; the overall CBR value agreed with the UCS test. The reaction products calcium silicate hydrate and ettringite are the controlling mechanisms for the mechanical performance of CKD-stabilized sediments, whereas calcium aluminate hydrate is the control for lime-stabilized sediments. These results will contribute to the use of CKD as a sustainable and novel stabilizer for lime in highway material applications.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.87-100
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• 2016

Biochar, which has high alkalinity, has widely studied for amendment of soil that contaminated with heavy metals. The aim of this study is assessment of amendment for arsenic and heavy metals contaminated acidic agricultural soil using biochar that derived from buffalo weed (A. trifida L. var. trifida). Pot experiments were carried out including analysis of soil solution, contaminants fractionation, soil chemical properties and plant (lettuce) uptake rate. Arsenic and heavy metals concentrations in soil solution showed relatively low in biochar added experiments when compared to the control. In the heavy metals fractionation in soil showed decrease of exchangeable fraction and increase of carbonates fraction; however, arsenic fractionations showed constant. Soil chemical properties indicated that biochar could induce recovery of soil quality for plant growth in terms of soil alkalinity. However, phosphate concentration in biochar added soil decreased due to Ca-P precipitation by exchangeable calcium from biochar. Arsenic and heavy metals uptake rate of plant in the amended experiment decreased to 50% when compared to the control. Therefore biochar derived from buffalo weed can be used as amendment material for agricultural soil contaminated with arsenic and heavy metals. Precipitation of As-Ca and metal-carbonates are major mechanisms for soil amendment using char.

• Geomechanics and Engineering
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• v.15 no.2
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• pp.729-738
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• 2018

Soft clay soils due to their various geotechnical problems, stabilized with different additives. Traditional additives such as cement and lime will not able to increase the soil strength properties significantly. So, it seems necessary to use new additives for increasing strength parameters of soft clay soils significantly. Among the new additives, epoxy resins have excellent physical and mechanical properties, low shrinkage, excellent resistance to chemicals and corrosive materials, etc. So, in this research, epoxy resin used for stabilization of soft clay soils. For comprehensive study, three clay soil samples with different PI and various clay mineral types were studied. A series of uniaxial tests, SEM and XRD analysis conducted on the samples. The results show that using epoxy resin increases the strength parameters such as UCS, elastic modulus and material toughness about 100 to 500 times which the increase was dependent on the type of clay minerals type in the soil. Also, In addition to water conservation, the best efficiency in the weakest and most sensitive soils is the prominent results of stabilization by epoxy resin which can be used in different climatic zones, especially in hot and dry and equatorial climate which will be faced with water scarcity.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.73-77
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• 2003

Red mud is a waste material formed during the production of alumina when the bauxite ore is subjected to caustic leaching. It is a brick-red colored highly alkaline (pH 10-12) sludge containing mostly oxides of iron, aluminum, titanium, and silica. Red mud, due to its high aluminum, iron, and calcium contents, has been suggested as a cheap adsorbent for removal of toxic metals (e.g., As, Cr, Pb, Cd) as well as for water or wastewater treatment. The basic advantage of red mud is its versatility in application. This study was conducted to evaluate the effect of red mud on stabilization and fixation of heavy metals (such as Pb, Cu, C $r^{6+}$, Cd, Zn) contained in the Al-coating sludge and soil. The results showed that the concentration of heavy metals leached from the treated sludge and soil was low, meeting the regulatory permit level.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1996.12a
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• pp.97-101
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• 1996

Municipal and sanitary landfills can pose environmental problems due to leachate, landfill gas md unstable geotechnical properties. Most governmental bodies delay the correction of landfill problems or landfill replacement until a crises stage is reached. The replacement of a landfill is often made difficult due to costly regulatory controls, public opposition to siting and the high cost of closure for the previous landfill unit. Solutions to extending landfill life and capacity Involve waste minimization by recycling, refuse compaction and waste-to-energy incineration. Incineration can reduce the volume of refuse by 50-95%. The largest installed bases of municipal waste Incinerators are located in Japan and the U.S. The volume of waste contained in a landfill can be estimated by load count tabulations, weight-and-volume measurements or a material balance analysis based on the trash profile of user categories. for an existing landfill, core samples may be collected and analyzed for use in a material balance analysis. Newly generated refuse contains approximately 50% of the heating value of coal. However, landfill properties vary significantly due to the waste profile of the contributors and biodegradation due to time and weathering. The volume of the Nanji-do landfill

• Journal of the Korean GEO-environmental Society
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• v.13 no.1
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• pp.45-51
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• 2012

This article aims to find method to mix a harmless hardening agent and soil generated during construction to make paving materials. The main purpose of this research is to get rid of the harmfulness(Chromium (VI), etc.) of cement which has been generally and frequently used as a hardening agent and strengthen it so that it can be used for the general foundation solidification and stabilization of civil engineering/construction structures such as dredging soil treatment, marine structure foundation treatment, surface soil stabilization, and river bank erosion prevention. NSS(Natural Stabilizer Soil) used for this study takes as its chief ingredient the mixture of lime and staple fibers extracted from natural fibers. It increases the shearing strength of soil that it improves the support and durability of the foundation and prevents flooding and frost as well. The pH measured to know its eco-friendliness was 6.67~7.15, and according to the migration testing, only Pb and CN were lower than the standards, so it can be said that NSS has almost no harmful components in it. According to the result of uniaxial strength testing, when the mixture ratio of weathered soil to NSS was 6%, about 1,850kpa strength was expressed. And according to the result of CBR. testing to figure out its appropriateness as a paving material, the CBR of the foundation was 4%~6%. But when the mixture ratio of NSS is over 6%, the water immersion CBR. is over 100%; thus, it is expected that it will show great utility as a paving material.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.3
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• pp.33-42
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• 2005

The bearing methods using pile of steel itself or reinforced concrete has been applying which in excavated depth was not deep. Also, the retaining wall as resisting structure to lateral force has taken weakness that the cure periods of concreted is long. Recently, with the material cost of steel, the application of cement is more increasing trend. In this study, the design methods of earth retaining and retention wall within the pre-casted concrete pile, PHC(Pretentioned spun High strength Concrete piles), was proposed which in the ground condition of excavated depth was not deep. The typical ground conditions, cohesive and non-cohesive soil, was considered as follows; soil strength as internal friction angle and UU(Undrained Unconsolidation triaxial test) strength, soil reaction and stabilization of structures. The application of design methods could be confirmed through the comparing and analyzing between measured data and utility software for the design.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.45-54
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• 2011

In this study, the consolidation characteristics are investigated on the artificial soil mixture of kaolinite, fine soils representing dredged soils and reclaimed coal ash from the ash ponds. A large sedimentation chamber was designed and manufactured to produce the artificial soil mixture with uniform stress history. In order to examine the consolidation characteristics in lateral and vertical directions, standard consolidation and Rowe Cell tests were performed. From the results of standard consolidation tests, the artificial soil mixture with coal ash showed lower compressibility and the larger consolidation coefficients enough to aid in early stabilization of the reclaimed sites compared with the kaolinite only. Also, in order to examine the consolidation characteristics when applying vertical drains, the drainage material was installed and tested in the Rowe Cell. The Rowe Cell test results show that the artificial soil mixture yields higher coefficient of consolidation. Thus, the application of artificial soil mixture on the reclaimed sites can shorten the consolidation time.

• Journal of Environmental Science International
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• v.19 no.7
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• pp.901-905
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• 2010

Emissions of leachate, odor, and landfill gas(LFG) from an open-dumping landfill site do harm to public health by contaminating neighboring soil, underground water, and rivers. Particularly, methane($CH_4$) and carbon dioxide($CO_2$), the main components of LFG, are especially noted as the causing material of the global warming that become seriously recognized worldwide issue. As one of alternatives in managing LFG, incineration of inflammable wastes that are generated during excavation process at an open-dumping landfill has been evaluated. Standard on stabilization for evaluation, neither $CH_4$ density nor $CO_2$ density could not Because meet 'less than 5%' criterion and so it is right to install a gas collection system during landfill renewal to prevent diffusion of odor and collect it. Because it shows considerable heating value, incineration of inflammable wastes might be the reasonable solution from the result of our study.