• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.190-197
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• 2020

This paper evaluates the mechanical properties and durability of cement matrix blended with mineral admixtures and ferronickel slag(FNS) powder which is an industrial b y-product during ferronickel smelting process. The hydration heat, pore structure, compressive strength, length change, rapid chloride penetration test(RCPT), and freezing and thawing resistance of ternary blended cement matrix were investigated and compared with ordinary portland cement matrix. The result showed that the compressive strength of ternary blended cement matrix using ferronickel slag powder and mineral mixture was low in strength compared to the reference concrete, but recovered to a certain extent by using alkali activator. Length change of cement mortar using FNS powder have shown less shrinkage occurs than the reference specimen. In addition, irrespective of using the alkali-activators, all ternary mix are indicative of the 'very low' range for chloride ion penetrability according to the ASTM C 1202, and the freeze-thaw resistance also showed excellent results.

• Tunnel and Underground Space
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• v.19 no.4
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• pp.287-303
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• 2009

Rock mass in Baekrokdam at the summit of Hallasan in Jeju island is composed of two volcanic rock types: Baekrokdam trachybasalt at the eastern region and Hallasan trachyte at the western region. On-going rockfall and subsequent collapse of Baekrokdam wall rock are closely linked to the weathering of trachyte distributed in the western region of Baekrokdam. Samples of Hallasan trachyte showing different weathering grades had been collected and the polarizing microscopic observation, X-ray diffraction analysis and analysis for chemical weathering had been conducted. Formation of secondary minerals, especially clay minerals, by chemical weathering has not been identified, but the change of chemical weathering indices indicated that chemical weathering process had been proceeded to the degree for increasing and decreasing the contents of some chemical components. Changes in physical and mechanical rock properties due to weathering has also been examined. Artificial weathering test of freezing-thawing reveals that the process of crack initiation and propagation deteriorated the mechanical characteristics of Hallasan trachyte and $D_B$ = 1.5 or porosity = $20{\sim}21%$ would be the ultimate limiting value induced by the mechanical weathering processes.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.5-15
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• 2011

Conventional designs of landfill covers use geosynthetics such as geomembrane and GCL, and clay liners to lower the permeability of final covers of landfill sites. However, differential settlement and the variation of temperature or humidity in landfill sites cause the development of cracks or structural damage inside the final cover. This study examined the application of a Self Recovering Sustainable Liner (SRSL) as an alternative landfill final cover material. SRSL consists of double layers, which have chemicals, can generate precipitates filling the pores of the layers by chemical reaction. The interface material forms an impermeable layer and in case of internal cracks, the reactants of the two layers migrate towards the crack and heal it by forming another liner. In this study the applicability of SRSL material for landfill final cover was examined by performing flexible wall permeameter tests to prove that the hydraulic conductivity is lower than the regulations and unconfined compression tests to judge whether the strength satisfies the restriction for the landfill final cover. Furthermore, the environmental impacts on the permeability and strength were evaluated. The experimental results show that the SRSL has lower hydraulic conductivity and higher strength than the regulations and is little influenced by climatic changes such as wet/dry or freeze/thaw process.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.686-691
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• 2009

Damage due to frost action in pavement structure system is creating either frost heave or stiffness-weakening of subgrade soil follow melting. The formation of ice lenses requires a frost-susceptible soil, freezing temperatures, and continuous water supply. Eliminating one of these conditions suffices to significantly reduce the intensity of frost action. It is important to know characteristics of subgrade soil in frost susceptibility or decide degree of freezing permission. Also, study on the stiffness variation of subgrade soil during freezing and thawing cycle is very important. In this study, Impact resonance test for subgrade soil at freezing and thawing confirms that is applied for.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.15.1-20
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• 1995

일반적으로 일반 및 유해폐기물 매립지에서 진흙층의 기능적 수행목적은 다음과 같다고 할 수 있다. 지표면 유출의 증진을 위하고, 우수의 침투억제 및 폐기물의 표면 노출 시 완충작용, 따라서 최종복토의 붕괴는 이러한 중요 기능을 마비시키고 있다. 본 연구는 추운 날씨상태의 폐기물 매립지 최종복토의 거동을 수행하였으며, 실제로 설계된 세 개의 거대한 실험실 Tank에서 복토에 대한 실험이 시행되었다. 이 거대한 실험장비의 제원은 0.75m x 2.4m와 2.0m 깊이로 되어 있다. Tank안은 시방서적으로 폐기물 매립지가 요구하는 진흙층과 최종복토를 위한 물질로 채워졌다. 그들의 실험결과는 동질/융해에 따른 진흙과 복토층의 붕괴현상은 물리적, 공학적인 측면에 영향을 주는 것으로 나타났다. 본문은 실험에 사용된 복토층의 묘사, 그들의 실험결과들과 실험을 통한 결과분석 및 결론을 설명하고 있다. 실험결과로서는 각 모형들의 우수와 침출수 자료, 온도변화의 배경과 최종복토에서의 Water Balance를 포함하고 있다. 또한 결과로서 시험된 세 개의 모형들은 매립지에서의 동결깊이(29cm~32cm)를 나타내주며 그들 중 하나의 모형은 배수층을 가지고 있어 침출수억제에 효과적이므로 다른 모형보다 복토층으로서 우위에 있다는 것을 지적하고 있다.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.4
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• pp.47-54
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• 2010

This study is progressed function ratio, it's trued taste by an experiment to present data for human work light weight aggregate development that use clink ash progressed liquid limit, small success limit, wear loss in quantity, sand equivalent, sieve cutting examination. 80:20's match of function rain examination is 1.4, and that use rubble aggregate as recyeled-panit lightweight aggregate's capacity ratio increases by 1.0 increase of function rain many. Also, examination multiplied delicate flavor gradually according to increase of the mixing rate, and absorption coefficient increased. This is judged by phenomenon that appear by special quality upper recycled-panit of polystyrene bid and porosity's increase between lightweight aggregate. It is case that use aggregate of wear loss in quantity is 13.5 in sand equivalent and a wear loss in quantity experiment and although case that mix 20% increases by 14.4, this phenomenon by weak tissue of lightweight aggergate be judged. When it's as a these experiment, the statue prevention floor of a street improvement specifications is prescribing so that satisfy by sand equivalent 20, CBR 10. This is showed result that this satisfies in quality standard all in match experiment ago that see.

• Journal of the Korean GEO-environmental Society
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• v.14 no.7
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• pp.19-29
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• 2013

Analysis via classical soil mechanics theory is either ineffective or inappropriate for fully describing stress distribution or failure conditions in cold regions, since mechanical properties of soils in cold regions are different from those reported in the classical soil mechanics theory. Therefore, collecting and analyzing technical data, and systematic and specialized research for cold regions are required for design and construction of the structure in cold regions. Freezing and thawing repeat in active layer of permafrost region, and a loading condition affecting the structure changes. Therefore, the reliable analysis of mechanical properties of frozen soils according to various conditions is prerequisite for design and construction of the structure in cold regions, since mechanical properties of frozen soils are sensitive to temperature condition, water content, grain size, relative density, and loading rate. In this research, the direct shear apparatus which operates at 30 degrees below zero and large-scaled low temperature chamber are used for evaluating shear strength characteristics of frozen soils. Weathered granite soil is used to analyzed the shear strength characteristics with varying freezing temperature condition, vertical confining pressure, relative density, and water content. This research shows that the shear strength of weathered granite soil is sensitively affected by various conditions such as freezing temperature conditions, normal stresses, relative densities, and water contents.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.103-111
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• 2010

Recently, usage bicycle has been encouraged to reduce energy consumption and $CO_2$. For this purpose, lots of bike road construction are planned. Typical type of pavement used in bikeroad such as asphalt concrete pavement, portland cement concrete pavement, colored pavement, soil pavement. However, these pavement types may need high construction cost comparing the required capacity of bike road. In this study, roller compacted concrete pavement which are economical and durable, are investigated to use as bike road pavement. The optimum compaction level and mix design of roller compacted concrete pavement are suggested by exploring strength test with various mixture ratio and compaction level, Also durability was examined based on freeze-thaw and scaling test. In addition, the cost and amount of carbon emission during in the construction of roller compacted concrete were evaluated and compare with the cost and carbon emission of typical portland cement concrete.

• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.202-208
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• 2013

The method used to test lightweight aggregate concrete for its resistance to freezing and thawing is different in each country. In Korea, the method of KS F 2456 on normal concrete is adopted for lightweight aggregate concrete, while the testing method of ASTM C 330 lightweight aggregates for structural concrete is used in the majority of overseas countries. In this study, we identified differences between KS F 2456 and ASTM C 330 in terms of the testing method for freezing and thawing resistance, and we studied the influence of this on the freezing and thawing resistance of lightweight aggregate concrete. The results of this study were as follows: Blocked lightweight aggregates had a slight collapse of shape and lost weight by repeated freezing and thawing, but unblocked lightweight aggregates were badly collapsed. And while the freezing and thawing resistance tests of normal concrete showed similar results despite the difference in the KS and ASTM testing method, the results for lightweight aggregate concrete were very different. So the KS test method shows evaluation results that are much lower than the ASTM test method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.235-242
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• 2005

This study is on the evaluation of performance of polymer cement mortar which is used for pre-wetting spray method. Pre-wetting spray method is an epoch-making method to repair concrete structures damaged, which is added a small quantity water preciously to dry mortar to reduce dust and rebound and spray mortar mixed with fixed quantity water at nozzle before spray. The result showed that physical performance such like compressive, flexural and adhesive strength of polymer cement mortar, TS 100 used for pre-wetting spray method was superior to other repair mortar. Also durable performance such as resistance on permeability of chloride ion, carbonation, chemical and freezing-thawing was excellent.