• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.2
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• pp.107-113
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• 2013

This study is the study desiring to solve the problem by utilizing the kinds of recycled resources considered to be troubled complementarily. Namely the reaction of potential hydraulicity of Blast Furnace Slag Powder (BS) shall be reacted with the alkali of Recycled Fine Aggregates Coarse Aggregate, it has been experimented to obtain the optimum value with the replacement ratio of incineration plant ash (WA) treated with the slaked lime as the experiment variable by solving the alkali of shortage with the Ordinary Portland Cement (OPC). As a result, the liquidity and the air volume are declined slightly as the replacement ratio of incineration plant ash WA increases, the mixture of incineration plant ash WA 1% has been analyzed to be the most suitable considering the viewpoint of effective handling of waste as the compression and the tensile strength showed the maximum value before and after 1% even though it was disadvantageous with the increase of chloride content.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.107-115
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• 2019

The many countries are facing the shortage of natural resources, and the supply of aggregates are being exhausted. To consider this situation a variety of studies were performed for the development of alternative resources. In particular, high density filler material was used for shielding radioactive waste, large amount of natural aggregates are required in order to produce filler material. Also, in order to improve the shielding performance of filler material, it is required to increase the density of the filler material. Therefore, in this study was carried out to provide basic data for expanding the feasibility of high density industrial waste resource as aggregate in heavyweight concrete. From the test results, OPC case, concrete strength decreased by using heavyweight waste glass as fine aggregate, however, it is improved by using mineral admixture as binder. Therefore, when the heavyweight waste glass and steel slag are applied to heavyweight concrete, it is desirable to use mineral admixture, especially to use BFS than FA. Meanwhile, when the steel slag was replaced as coarse aggregate of heavyweight concrete, elasticity of modulus and radiation shielding performance can be improved owing to high density of steel slag.

• Journal of the Korean Geosynthetics Society
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• v.11 no.2
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• pp.31-38
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• 2012

The recycled aggregate for construction, slag, coal ash and such may elute leachates by chemical reaction when in touch with water, and to confirm this, generally the waste process test is executed. If the test result criteria are met, it can be used as replacement aggregate. In case of steel slag, however, the chemical reaction does not end in a short term, but occurs over a long time, generating eluted leachate. Thus, in this study, the leachate from steel slag were analyzed for heavy metal, and the pH change and environmental characteristics of eluted leachate were analyzed. According to the experiment result, the chemical reaction of free CaO and water within the steel slag occurred more actively when stirred, and the smaller the grain size, the higher the pH was. As the result of waste process test, all test items for the two types of specimen were found to have no heavy metal, but from the ICP test analysis result, heavy metals such as Al, Pb, Zn, Fe were detected. It could be confirmed that chemical reaction would occur upon contact of steel slag and water, and heavy metal may be detected depending on experiment conditions and analysis methods, the long-term environmental characteristics should be examined for utilization of steel slag.

• Proceedings of the Korea Concrete Institute Conference
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• 1989.10a
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• pp.1-4
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• 1989

Recently, as the natural aggregates are exhausted, using the crashed stones bring the possibility of the alkali-aggregate reactivity. In this study, the samples are collected from the stony moutains chosen by using a geoligical survey map and analyzed in terms of the amount and the shape of the reaction minerals by a polarization microscope and X-ray diffraction which beling to the petrographic examination of aggregates for concrete. From this study, most samples of the sedimentary rocks and the granitte of the ignious rocks show the possibility of the alkali-aggregate reactivity.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.97-102
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• 1993

In the country, due to short comings of natural aggregates of good quality, it is common to use crushed stones. However, the investigation has not been done on the chemical reaction of crushed stones. This study tested and analyzed the aggregate chemical reaction by Petrographic Examination(ASTM C 295),Chemical Metho(ASTM C 289) and Mortar-Bar Method (ASTM C 227). As a result, most of test aggregates didn't show any reaction but many have common deleterious mineral. Therefore, there exists the possibility of chemical reaction in petrographic point of view.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.33-38
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• 2022

As the intense heat continues, many cases of highway pavement blow up and bridge expansion joints damages have been inspected. Especially, Expansion joint closure of bridges is an important problem that can threat the safety of the bridge structure or reduce long-term durability. This paper proposed a structural analysis method for bridges having expansion joint closure and structural analysis was performed to verify the effects according to bridge types. Analysis bridges were divided into four types: concrete and steel bridges, shallow and piled foundations. To induce the situation of abutments and bridge decks are jammed, the following loads were additionally considered; lateral flow pressure, pavement expansion by alkali-aggregate reaction, creep settlement of backfill. The structural analysis method was verified by comparing the structural analysis results with the actually measured joint gap data. In addition, behavioral analysis due to joint closure was conducted to confirm the change in safety ratio by type of superstructure as the axial force increased.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.6
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• pp.277-282
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• 2007

The artificial lightweight aggregate (ALA) was manufactured using coal bottom ashes produced from a thermoelectric power plant with clay and, the sintering temperature and batch composition dependence upon physical properties of ALA were studied. The bottom ash (BA) had 13wt% coarse particle (>4.75mm) and showed very irregular shape so should be crushed to fine particles to be formed with clay by extrusion process. Also the bottom ash contained a many unburned carbon which generates the gas by oxidation and lighten a aggregate during a sintering process. Plastic index of green bodies decreased with increasing bottom ash content but the extrusion forming process was possible for the green body containing BA up to 40wt% whose plastic index and plastic limit were around 10 and 22 respectively. The ALA containing $30{\sim}40wt%$ BA sintered at $1100{\sim}1200^{\circ}C$ showed a volume specific density of $1.3{\sim}1.5$ and water absorption of $13{\sim}15%$ and could be appled for high-rise building and super-long bridge.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.549-561
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• 2005

이 연구의 목적은 새로이 제작된 chitosan-poly(L-lactic acid)(PLLA) 다층 다공성 차폐막의 생체적합성 및 골세포활성도 및 골재생능을 평가하는 것이다. 제작된 차폐막을 24 well에 넣고 clonal osteoblast-like cell line(MC3T3-E1)을 접종한 군을 실험군으로, 차폐막을 사용하지 않은 대조군으로 하였다. 배양 1일, 7일 및 14일째에 각 well에서 세포수를 측정하였다. 주사전자현미경을 이용하여 차폐막에 부착된 세포의 형태관찰을 시행하였다. RNA 추출 및 RT-PCR을 실시한 후, agarose gel상에서 전기영동하여 조골세포 표식자인 collagen type I(COL), osteopontin(OP) 및 osteocalcin(OC) mRNA의 발현을 관찰하였다. 제작된 매트릭스의 생체적합성 및 골재생능을 관찰하기 위하여 백서의 두개골에 직경 8mm의 원형 결손부를 형성한 후 차폐막을 이식한 군을 실험군으로, 아무 것도 넣지 않은 군을 대조군으로 하여 4주 경과 후 실험동물을 희생시킨 후 조직학적관찰을 시행하였다. 시간경과에 따른 부착세포수 관찰결과, 배양 14일까지 조골세포의 수가 지속적으로 증가하였고, 주사전자현미경으로 세포의 형태 관찰결과, 배양된 세포들은 중층의 형태로 성장하면서 시간경과에 따라 세포가 응집되는 양상을 나타내었다. 관찰 기간동안 COL, OP, 및 OC mRNA의 발현이 관찰되어 배양 전 기간동안 조골세포의 형질이 잘 유지되고 있음을 알 수 있었다. 백서 두개골 결손부에 이식된 차폐막은 염증반응 없이 주위 조직과 우수한 생체적합성을 나타내었으며, 차폐막을 이식하지 하지 않은 대조군에 비해 높은 신생골 형성을 나타내었다. 이상의 관찰결과로 새로이 제작된 chitosan-PLLA 차폐막은 우수한 생체적합성 및 골재생능을 나타냄을 알 수 있었으며, 향후 이를 골조직 재생 및 치주조직유도재생 분야에 응용될 수 있을 것으로 생각된다.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.577-584
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• 2007

The effect of steel microfibers (SMF) on alkali-silica reaction (ASR) was investigated using two types of reactive aggregates, crushed opal and a pyrex rod of constant diameter. Cracks are less visible in the SMF mortars compared with the unreinforced mortars. Due to crack growth resistance behavior in SMF mortar specimens, the strength loss is eliminated and the ASR products remained well confined within the ASR site. The expansion and the ASR products were characterized by microprobe analysis and inductively coupled plasma (ICP) spectroscopy. The confinement due to SMF resulted in a higher Na and Si ion concentration of the ASR liquid extracted from the reaction site. The higher concentration reduced the ASR rate and resulted in a lower reactivity of the reactive pyrex rods in SMF mortars.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.435-438
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• 2005

The effect of content of reactive aggregate on alkali-silica reaction was investigated through the ASTM C 1260 method. The replacement proportions of fine aggregate by reactive aggregate were 25, 50, 75 and $100\%$, respectively. Reactive aggregate and fine aggregate(non-reactive aggregate) used are a metamorphic rock and andesite rock, respectively. The results indicate that the mortar-bar containing $25\%$ replacement of fine aggregate by reactive aggregate shows the lowest expansion but expansion in excess of $0.1\%$ at 16 days, which can distinguished between deleterious and potentially reactive. Although content of reactive aggregate is a small amount, it can cause detrimental expansion due to alkali-silica reaction.