• Magazine of the Korea Concrete Institute
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• v.14 no.4
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• pp.40-48
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• 2002

콘크리트는 시멘트의 수화반응으로 시간이 경과하면 굳어지게 되는 물질이다 따라서 레미콘 생산시 기기 및 장비 등에 고착된 콘크리트는 가수 혼합 등으로 분해가 불가능하므로 일단 콘크리트의 제조 및 운반작업이 종료된 후에는 즉시 세척하여야만 한다. 특히 레미콘 생산 현장에서와 같이 대량의 콘크리트를 제조할 경우에 있어, 일단의 콘크리트가 생산완료된 후 레미콘 트럭의 드럼내ㆍ외부 및 배치플랜트의 믹서ㆍ호퍼 등의 세척은 후속콘크리트 제조시 배합비의 정밀을 기하거나, 장비의 보존을 위하여 반드시 필요하게 되는데, 이때 발생하는 세척배수에서 골재를 제거한 것을 회수수라 한다.(중략)

• Resources Recycling
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• v.25 no.2
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• pp.49-59
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• 2016

Steel slag is being recycled into industrial by-products for civil generated inevitably in the seasonal course, road and cement raw materials. However, the field of recycling most of the bottom portion is concentrated in the areas that are required to take advantage of the situation in various fields taking advantage of the steel slag. But various studies to take advantage of the steel slag as aggregate for concrete made for limiting slag was a situation that most of the studies are incomplete research on the suitability of as aggregate for concrete practical relates to an expandable suppressed. In this study, the separation of the slag aggregate according to the production methods to assess the feasibility aggregate for concrete aggregates, including through Steel making slag, a total of seven kinds of steel slag aggregate. Studies show that ordinary concrete, steel slag aggregate for aggregate and on the equally to take advantage of grading, chloride content standards such as to what is lacking, although appropriate aggregate of concrete include the deployment of only in special sectors through the combination was assessed to have a very high.

• Korean Journal of Agricultural Science
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• v.32 no.1
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• pp.19-27
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• 2005

This study was performed to evaluate the physical and mechanical properties of polymer concrete using unsaturated polyester resin, initiator, heavy calcium carbonate, crushed gravel, recycled coarse aggregate, silica sand and recycled fine aggregate. The unit weight, compressive strength, flexural strength and dynamic modulus of elasticity were decreased with increasing the content of recycled aggregate. The unit weight, compressive strength, flexural strength and dynamic modulus of elasticity were showed in $2,127{\sim}2,239kg/m^3$, 80.5~88.3MPa, 19.2~21.5MPa and $254{\times}10^2{\sim}288{\times}10^2MPa$ at the curing age 7 days, respectively. Therefore, these recycled aggregate can be used for polymer concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.276-283
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• 2016

Red mud is an inorganic by-product produced from the mineral processing of alumina from Bauxite ores. the development of alkali-activated slag-red mud cement can be a representative study aimed at recycling the strong alkali of the red mud as a construction material. This study is to investigate the optimum water content, compressive strength, moisture absorption coefficient and efflorescence of alkali-activated slag-red mud soil pavement according to the recycling fine aggregate content. The results showed that the optimum water content, moisture absorption coefficient and efflorescence area of alkali-activated slag-red mud soil pavement increased but the compressive strength of that decreased as the recycled fine aggregate content increased.

• Explosives and Blasting
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• v.22 no.2
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• pp.21-32
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• 2004

산업용 화약은 19세기 중엽부터 외국인에 의해서 수입된 화약류를 채광목적에 이용하기 시작한 것으로 전해 오고 있으나, 본격적으로 현대화약이 사용된 시기는 1930년대부터 국내 지하자원을 개발하면서라 할 수 있다. 1935년에는 홍남에 대규모 화학단지를 조성하였고 1940년에는 인천에 독립적인 화약공장이 세워져 국내 화약류가 본격적으로 생산되게 되었다. 그러나 1940년부터 보관된 자료는 없고 일부 존재하기는 한데 대부분 신빙성이 없는 자료들뿐이다. 화약류는 세계적으로 대부분 광업분야에 주로 이용되었다. 하지만 국내건설산업이 크게 발달하면서부터 광업분야보다 건설분야에 많이 이용되어지고 있다. 건설분야 중에서도 특히 건축, 토목, 시멘트, 골재생산에 폭약사용이 증가되어 왔다고 생각되어지나 화약류 생산에 대한 1990년 이전 자료들이 거의 없거나 불명확한 자료들이었다. 본 연구에서는 폭약에 따라 차이가 발생하는 폭열을 기준으로 비교될 건설기성액에 대하여 폭약총생산량의 폭약을 폭약등가톤수(Tons of explosives equivalent; TOEE)로 적용하여 1990년부터 최근 11년 간 화약생산량을 근거하여 2000년까지 건설경기동향과 폭약생산량의 상관관계 추이를 밝혀 국내 건설산업과 폭약생산량 증감의 경향을 연구하고자 하는데 그 목적이 있다.

• Journal of Korean Society of Forest Science
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• v.80 no.1
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• pp.72-81
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• 1991

This study was carried out to provide necessary information for improving quarrying industry management in Korea. The results of the study are summarized as follows : 1. In aggregate and building-stone quarrying firms the managers over 40 years of age are 97% and 89.1%, the ones above education level of high school are 90% and 85% and the ones not more than 10 years of quarrying experience are 70% and 52%, respectively. Accordingly it can be pointed out that most of the managers of two types of firms are relatively old, have high educational background, while quarrying experiences of building-stone firm managers are longer than that of aggregate firm managers. 2. Most of the management forms are social corporation(60%) for aggregate quarry firms and private management(76%) for building-stone firms. Average areas of permitted stone-pits of aggregate and building-stone quarries are about 2.86ha and 1.66ha respectively. That is, aggregate quarrying firms are carried on a larger scale than building-stone quarrying firms. 3. The yearly average product of aggregate quarrying firms has increased steadily from $88.961m^3$ in 1985 to $144.028m^3$ in 1988, while, in case of building-stone quarry firms, it has significantly increased from $4.155m^3$ to $19.462m^3$ from 1985 to 1987, but reduced to $13.400m^3$ in 1988. Unstable production activities of building-stone quarrying firms may require continuous government support. 4. Major cost items are equipment rental, depreciation, salaries, repair, maintenance for aggregate quarrying firms, and salaries, depreciation, fuel, tax for building-stone quarrying firms. The yearly average rate of return is about 9.7% for aggregate quarry firms and 2.6% for building-stone quarry firms. It can be pointed out that aggregate quarrying firms is better managed than building-stone quarrying firms. 5. The production elasticity of salary for aggregate quarrying firms is 0.495, that of employees is 0.559, and that of capital service is 0.513. The sum of the elasticities is 1.257>1. Fur building-stone quarrying firms, that of employees is 0.492, that of variable costs is 0.192, and that of capital service is 0.498. The sum of elasticities is 1.172>1, thus denotes the increasing returns to scale for both types quarrying firms. 6. The ratio of marginal value product to opportunity cost of empolyees is 2.54, that of variable costs is 3.62, and that of capital service is 1.45, in aggregate quarrying firms. That of employees is 2.47, that is variable costs was 2.34, and that of capital service is 19.67 in building-stone quarrying firms. Therefore the critical factors for more expansion of management scale in aggregate quarrying firms are variable cost and employees, and are capital service in building-stone quarry ing firms. 7. The break-even points of stone sales are about 0.587 billion won and 0.22 billion won in aggregate and building-stone quarrying firms respectively. The optimum sales Level for profit maximization are about 2.0 billion and 0.5 billion in aggregate and building-stone quarry firms respectively.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.88-93
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• 2011

To resolve the problem which is demand and supply imbalance of fine aggregate by the shortage of natural fine aggregate and the environment regulations, the studies for the application of recycled fine aggregate made from waste concrete have been recently carried out. The objective of this study is to shed light on the mechanical properties and durability performance of concrete using recycle fine aggregate with various water to cement ratios and unit water contents. And it is intend to propose the fundamental data for structural application of recycled concrete. In particular, the effects according to the variations of water to cement ratios and unit water contents in recycled concrete with recycled fine aggregate replacement of 100 percent are discussed by the test results, such as air content, slump, time of set, compressive strength, tensile strength, carbonation, chloride penetration.

• International Journal of Highway Engineering
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• v.6 no.4 s.22
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• pp.25-33
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• 2004

The waste concrete produced by the process of the highway construction and management, has been crushed in-situ, and the waste aggregate has been experimentally used for anti-freezing layer and lean concrete. After testing the bearing capacity on anti-freezing layer, it was found that when the waste aggregates mixed with natural sand would be within the required gradations, the layer meets the requirements of limitation and the percentage to passing 2$\sim$20mm sieve increased by 5$\sim$13% because the flimsy mortars on aggregate were re-crushed by vibrated-roller compactor. The compressive strength of lean concrete using recycled aggregate was 71$\sim$85% of the natural coarce aggregate made, but nevertheless the recycled aggregates are applicable to the lean concrete because they largely exceeded the required strength, $57.5kgf/cm^2$.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.420-427
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• 2022

The present study evaluated the physical, mechanical and thermal properties of the foam glass aggregate and insulation foundation with this, in order to promote the use of insulated foundations using domestically produced foamed glass aggregates. As a result of the evaluation, the compacted foam glass aggregate showed at the same level as overseas products in terms of unit volume mass, particle size and other characteristics, and a compressive strength of 40.6 N/cm², which was superior to the existing organic insulation materials such as XPS. And the thermal conductivity of the foam glass aggregate was 0.84 W/mK, and the thermal transmittance of the specimen simulating the insulation foundation was 0.37 W/mK, so the thermal conductivity of the foam glass aggregate was estimated to be 0.80 W/mK. With these results, it was found that it is possible to use the insulation foundation with re-producted foam glass aggregate by crushing the waste from the process of producing foam glass products.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.85-91
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• 2021

Aggregate waste separator with rotating separating net was designed for applying classification process of construction waste. In order to evaluate the performance of the aggregate waste separator, according to the type of waste, standardized waste samples are prepared using acrylic. The appropriate operating point was evaluated by the classification efficiency and misclassification rate of recycled aggregate according to the control frequency of the blower operating and inlet position of the separating net. The classification efficiency at the operating point of the aggregate waste separator was evaluated through flow analysis assuming recycled aggregate and waste sample as particles. As a result of the performance test, when the distance. between the conveyor belt and the inlet was 0.2m, the classification efficiency was 95%, but the misclassification rate of recycled aggregate was 2% or more, which satisfies the classification efficiency and the misclassification rate of less than 2%. The operating point was shown at a control frequency of 58Hz at a suction distance of 0.254m. As a resu lt of flow analysis, there was no misclassification of recycled aggregate. In order to redu ce constru ction waste in the existing recycled aggregate production process, adsorption system using a rotating separating net that can be operated as an installation type was built.