• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.72-73
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• 2013

In this paper, types of ready mixed concrete in construction site supported by different company has been researched. The practicability of the commercial available ready mixed concrete has been tested, and the standard deviation has been modified from Vc=Vo+3б to Vc=Vo+1.73б. Unnecessary premium rate has been cut and economical efficiency of the ready mixed concrete has been improved.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 산업계
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• pp.65-68
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• 2009

Recently, the knowledge access about concrete might be 2 methods. One is approach about advanced and new technical development through the institute journal, the other is construction technology which is using at construction fields. However, there is no research for the interrelationship between them. So, this paper investigates the demands on construction fields at the ready mixed concrete plants on the 4 cities, the characteristics of the products like the maximum size of coarse aggregate and slump, and the extension of market on the high strength and flow ability concrete in 2000 and 2008. Moreover, this study would like to propose the investigation about diversification of construction materials for the fine construction cultures and development of the ready mixed concrete to the engineers at the construction fields.

• 한국산업융합학회 논문집
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• 제2권1호
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• pp.45-52
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• 1999

It is difficult to keep the balance of supply and demand for natural aggregates in recent years, because natural resources have become to be almost exhausted. Crushed stone is already used for coarse aggregate instead of river gravel at present. Now, crushed sand or sea sand should be used for fine aggregate, because natural sand also has been exhausted with a few exceptions around Nakdong River. The sea sand has a lot of problems which are the corrosion of reinforcement bars, the investment of facility for cleansing salt and the cost increase due to the insufficiency of industrial water. Therefore, it is necessary to produce and to utilize the crushed sand very actively, but some material properties which are related to water absorption, strength and chemical durability, prevent from determining the generalized criteria because its rocks make much differences in its physical and chemical characteristics. In this paper, fundamental physical properties of crushed sand, which comes from Daegu Subway construction fields, have been investigated for the usability on basic material of concrete. The optimum replacement ratio and the strength estimation method of crushed sand replacing natural sand also have been presented here through the compressive strength test of ready-mixed concrete cylinders.

• 한국건축시공학회지
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• 제18권6호
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• pp.543-550
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• 2018

해안도시에 건설하는 건축물의 콘크리트 배합은 환경조건에 따라 설계기준 압축강도로 제한하고 있으나 혼화재 혼입에 의해 염해 내구성이 급격히 향상되고 있음이 기존연구에서 명확히 되고 있으나 아직 규정에 반영되고 있지는 못한 실정이다. 본 연구에서는 레미콘의 배합을 분석하고 비교 시험체 제작을 통하여 염해 내구성에 대한 건축구조기준을 만족시키면서 경제성을 가지는 결과를 도출하고자 하였다. 시판되는 레미콘의 경우 설계기준 압축강도 이상의 강도와 그에 따른 염소이온 차단성을 가지며 전 배합조건에 대해서 OPC 35MPa를 능가하는 성능을 확인할 수 있었다. 내구성 및 경제성을 동시에 달성하기 위해서 납품 전 사전배합을 실시하여 염해 저항성을 포함한 기본물성을 검토할 필요가 있다고 사료된다.

• 한국안전학회지
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• 제29권4호
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• pp.123-131
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• 2014

Whole amount of waste water, approximately 921.6 liter, for cleaning a ready mixed concrete truck should be used to produce concrete as a mixing water or cleaning water. Recycling water for concrete mixing contains solids, which cause decrease in slump, air and compressive strengths, so it may influence on poor concrete quality. Therefore, it has been maintained to use recycling water with less than 3 percent of solids. Since no evaluation system has been constructed to directly reflect on variability of recycling water from ready mixed concrete plants, it is necessary to develop "Automatic recycling solid measuring system" for quality controls in real time. In this research, sensors measuring waste water concentration in ultrasonic and inductance methods were developed, and automatic system using the sensors were established. The accuracy of measurement sensors developed for recycling water based on various conditions of concentration was proved, and application limits were evaluated. Also, concentration of recycling water using sensors developed from ready mixed concrete plant was measured, and curing method verified the accuracy of the sensors. Moreover, measurement sensors for recycling water in various locations were installed to evaluate the effects on measuring method and spots. The automatic measuring system for recycling water concentration, which is developed in the research, will contribute to improve concrete quality safety through reliable solids maintenance.