• KCI Concrete Journal
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• 제12권2호
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• pp.23-30
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• 2000

This paper presents behavior of concrete pavement at transverse joint subject to static test load. The test was conducted on 1/10 scale model in the laboratory. Load transfer across the crack is developed either by the interlocking action of the aggregate particles at the faces of the joint or by a combination of aggregate interlock and mechanical devices such as dowel bars. In this study, significant three variables considered to the performance of joints were selected. : (a)diameter of dowel bars(2.5mm, 3.0mm, 4.0mm), (b)presence or absence of dowel bars, (c)aggregate types(crushed stone, round stone). Experimental results were analyzed to find relationships among displacement of discontinuous plane at jointed slab, load transfer efficiency and joint opening, etc. Displacement of discontinuous plane at joint was decreased according to the increase of dowel bar diameter. In addition, it is found that model slabs made using crushed stone had better load transfer characteristics by aggregate interlock than model slabs made using similarly graded round stone. Displacement of discontinuous plane was increased according to the increase of loading. In addition, it was decreased as dowel diameter(2.5mm, 3.0mm, 4.0mm) was increased. In the case of slab without dowel bars, displacement of discontinuous plane was greatly increased and load transfer effciency of slab applied crushed stone was shown 30 percent greater than round stone. In addition, load transfer efficiency of slabs, which were made using crushed and round stone without dowel bars, was decreased to 20 percent and 30 percent, respectively as it was compared with slabs made us-ing dowel bars.

• 콘크리트학회지
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• 제9권3호
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• pp.119-126
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• 1997

최근 건설용 골재의 소비량이 증가하여 쇄석골재의 수요량이 급격히 늘어남에 따라 , 광산 현장에 적치 되어 있는 폐석을 효율적으로 활용하기 위한 연구가 활발히 진행되고 있다. 이 연구의 목적은 강원도삼화 지역에 분포하는 쇄석 골재용 석회암을 대상으로 암석 기재학적 화학적, 역학적 특성을 구명하여 건설용 골재로서의 적합성을 알아보고, 또한 부가가치가 높은 건설자재와 첨단산업소재 제품 개발의 원료로 활용할 수 있는 기초자료를 제공하는데 있다. 삼화지역에 분포하는 쇄석골재용 석회암은 크게 담회색의 세립질 석회암과 담갈색의 조립질 석회암으로 구분할 수 있었으며, 이중 양적으로 우세한 세립질 석회암은 돌로마이트가 함유되어 있어 MgO와 $SiO_2$의 함량이 높게 나타났고, 물성 및 역학적 특성을 고려할 때 보통암에 해당된다. 따라서 연구 지역의 쇄석골재용 석회암은 구성광물과 입자들의 크기 및 화학성분 등을 고려할 때, 대체로 시멘트 콘크리트용보다는 아스팔트 콘크리트용이나 도로 포장용 또는 철도용으로 이용하는 것이 더 좋을 것으로 판단된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.25-28
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• 2007

In this study we measured the changes according to time respectively on the basis of 0, 30, 60 and 90 minutes, taking into consideration the decline in fluidity of concrete according to elapsed time to analyze manufacturing capability of batcher plant according to elapsed time of ready-mixed concrete manufactured in batcher plant, and offer basic data for mixture design of ultra-high strength concrete. The proportion of water-binder was 23.55, water content was 160kg/m3, proportion of replacement of crushed sand was 0, 20 and 40% at 3 level, and we applied to the same condition of triaxial component using blast furnace slag powder and silica fume as admixture. And to meet the demand of certain fluidity, we measured respectively on property before and after hardening of ultra-high strength concrete using superplasticizer. As a result of experiment, before hardening of ultra-high strength concrete showed the best fluidity in conditions of crushed sand replacement rates of 20% and superplasticizer composition of 1.95%, but it appeared that fluidity drops as time goes by in the same composition condition. And it appeared that when it comes to hardened, the changes of compression strength according to elapsed time by crushed sand replacement rates were within 1MPa. Therefore, it turned out that the difference of strength according to elapsed time was low and compression strength of 280dys in composition mentioned above appeared highly as 88MPa.

• 한국지반공학회논문집
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• 제20권2호
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• pp.5-13
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• 2004

기존의 흙을 사용하여 건설된 철도 노반은 반복적인 교통하중의 증가, 열차속도의 향상, 노반상으로의 지하수의 유입, 노반의 배수능력 저하 등의 이유로 인해 시간경과에 따라 쉽게 그 기능을 상실할 수 있다. 본 연구에서는 실대형시험과 수치해석을 수행함으로씨 철도노반으로서의 쇄석강화노반의 성능을 평가하였다. 쇄석강화노반의 탄$.$소성 연직변위는 모사열차하중의 재하횟수에 관계없이 일반 흙노반에 비해 작은 응답특성을 보였으며, 동일한 노반 부설두께에서는 노반반력계수의 증가에 따라 감소하며, 동일한 강성인 경우 노반 부설두께 증가에 따라 감소하는 경향을 보였다. 하지만, 쇄석강화노반의 부설두께에 비해 노반의 강성이 궤도에 발생하는 전체 소성 연직변위에 더욱 큰 영향을 미치는 것으로 평가되었다.

• 한국지반공학회논문집
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• 제18권5호
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• pp.43-54
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• 2002

연약지반에 구조물을 시공하는 경우가 빈번해짐에 따라 연약지반 개량의 필요성이 증대하고 있다. Granular pile 공법은 연약한 점성토 지반이나 느슨한 사질토 지반의 개량에 사용되는 연약지반처리공법이다. 국내에서는 모래를 이용한 SCP공법은 종종 사용해 왔지만 쇄석을 이용한 Granular pile은 외국에 비해 그 사용실적이 미비한 실정이다. 그러나 모래자원의 고갈에 따른 환경적, 경제적 인 문제 때문에 모래 대신 이용할 수 있는 대체재의 필요성이 절실해지고 있다. 본 연구에서는 Granular pile 공법에 의해 개량된 연약한 점성토 지반의 거동 특성을 파악하기 위하여 모형토조를 이용한 하중재하 및 압밀시험을 실시하였다. 또한, Pile 재료로서 모래뿐만 아니라 쇄석을 이용한 실내모형시험으로 각각의 재료에 따른 지지력 특성 및 침하 특성, 배수 특성 등의 공학적 특성을 비교 평가하여 모래의 대체재로서 쇄석의 활용가능성을 검토하였다. 시험결과, 쇄석은 모래 재료에 비해 지지력증대와 침하저감효과가 크고, 유사한 간극수압특성을 보여 모래의 대체재료로서 쇄석의 활용이 가능하다고 판단된다.

• 한국유기농업학회지
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• 제19권spc호
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• pp.144-147
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• 2011

The main nutritional problem of sorghum${\times}$sudangrass hybrid (Sorghum bicolor${\times}$Sorghum sudanese) silage is low quality and palatability. This experiment was conducted to evaluate whether organic com grain and crushed rice addition of sorghum${\times}$sudangrass hybrid silage increases forage quality of the silage. The sorghum${\times}$sudangrass hybrid silages with added com grain and crushed rice were similar to conventional com silage in moisture content. However organic sorghum${\times}$sudangrass hybrid silage had low pH values. Silage added with gain and byproduct had higher crude ash, acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents than control com silages, while its non-fiber carbohydrate (NFC) and total digestible nutrients (TDN) showed the opposite results. Lactic acid, butyric acid and lactic percentage of total organic acid (L/T) of sorghum${\times}$sudangrass hybrid silages were higher than those of com silage, but acetic acid was higher than control. In vitro dry matter digestibility (IVDMD) of com silage was higher than other sorghum silages. Feed intake of sorghum${\times}$sudangrass hybrid silage added with crushed rice was highest among silages. Therefore, these data indicate that crushed rice and com grain added sorghum${\times}$sudangrass hybrid silage could be recommended as the most effective treatment for increasing silage quality and palatability.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.501-506
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• 2001

An experimental study was carried out to investigate recycling of an oyster shell, which is disposed in open-dumped way at coastal oyster factory area. For this purpose, the chemical component and reaction of oyster shell with cement paste was examined. And, the characteristics of hardened concrete was quantitatively investigated in terms of fineness modulus and blending rate of the crushed oyster shell. Test results show that interaction between oyster shell and cement paste was not occurred and the crushed oyster shell can be used as the fine aggregate of concrete. And it is found that blending of an oyster shell caused not to reduce the 28 day compressive strength of concrete. Elastic modulus of the concrete blended with crushed oyster shells decreases with increases the blending rate which the modulus reduced about 10% when oyster shells is blended up to the 20% of the sand substitution.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 봄 학술발표회 논문집
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• pp.169-173
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• 1994

Recently, the use of crushed stones is increased due to the shortage of natural aggregates. In the previous papers of part 1 and 2, we got the conclusions that some of crushed stones have the characteristic of alkali-silica reaction(ASR). And these reactions are influenced by the amount and type of alkali in cement. The purpose of this paper is how to prepare for the prevention against alkali-silica reaction. As a solution of problems, we have conducted the experiments of two methods. One was the replacement of innocuous aggregates instead of reactive aggregates, the other was the addition of various pozzolanic materials. As a result, we found that the expansion by alkali-silica reaction in mortar bar could be effectively decredsed by upper methods.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.417-422
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• 2001

The purpose of this study is to investigate experimentally the workability, compressive and flexural strength properties of rapid-set concrete with various mixture. The kinds of fine aggregate(river sand, sea sand, crushed sand), water-cement ratio(40%, 45%, 50%), sand-aggrega to ratio(33%, 36%, 39%) were chosen as the experimental parameters. Test variables are temperature of concrete, slump, air contents, compressive and flexural strength. The compressive and flexural strength for 3 hours and 6 hours were tested. As result, it was shown that temperature of concrete involved 45$^{\circ}C$, some time later decreased. The workability were decreasing in steps as the sand-aggregate ratio increased and crushed sand was the highest value. Higher compressive and flexural strength was shown following the order of river sand, sea sand, crushed sand regardless of sand-aggregate ratio. But the values of gap was just a little.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.447-450
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• 1994

The chemical method and mortar-bar method for identification of the susceptibility to Alkali-Aggregate Reaction (AAR) was established as KS method by referencing the ASTM methods. However, the chemical method requires skilled chemical engineers and aggregates are tested in very severe condition, and on the other hand, the mortar-bar method needs a long time of 3 or 6 months. Judging from this circumstance that the use of crushed stones are increased due to the shortage of natural aggregates, the development and standardization of a new rapid test method is considered essential. The purpose of this paper is to research for the possibility to apply the rapid method, instead of the chemical method and the mortar-bar method with using the several domestic crushed stones.