• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.229-234
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• 1997

The objective of this study is to develop the non crack ready mixed concrete and the high quality concrete under various addition ratios of expansive additives. According to the experiment results, when expansive additive are mixed in concrete mixture by about 6% per cement contents, in W/B of 45~55%, it is found that the strength increase and the shrinkage compensation can be achieved by about 2~3 times. And it is considered to produce high quality concrete and non crack ready mixed concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.257-262
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• 2001

There are only a few tests to ensure concrete quality before placing in domestic situ; One is slump test for workability, the other is air content test for durability, the concrete compressive strength which is one of important factors to influence on concrete Quality has been tested after 28 days placing. Methods on early judgement of concrete strength have been introduced for concrete quality management, but such methods are time consuming, expensive, and required special expertise. Therefore, these have difficulty in situ application for concrete management. This study aimed at reviewing application of estimated equation of compressive strength as means for ready-mixed concrete, making an estimated equation which enables to estimate 28 days compressive strength by using regression formula analysis on basis of mixing designs of ready mixed concrete and results of compressive strength.

• 한국건축시공학회지
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• 제14권1호
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• pp.11-20
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• 2014

This research examined the effect of the quality of aggregate on concrete workability and compressive strength through an investigation into regional aggregate used in domestic ready mixed concrete plants. Through the research, it was found that aggregate for ready mixed concrete shows poor quality overall. The main factor of deterioration in the quality of the concrete is the particle size of fine aggregate and fine particle content in coarse aggregate. The quality of aggregate significantly influences concrete's workability, which is defined based on 0.08mm passage related with powder and absorption. In addition, poor aggregate quality leads to increased water content in concrete to secure workability, which is related with a decline in the compressive strength and durability of concrete.

• 콘크리트학회논문집
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• 제18권2호
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• pp.199-204
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• 2006

최근 환경오염과 처리비용의 문제로 레미콘(ready mixed concrete) 회수수를 배합수로 재이용하기 위한 연구가 진행되고 있다. 그러나 회수수를 너무 많이 이용할 경우 콘크리트의 품질이 저하 될 수 있다. 이런 이유로 KS표준규정에선 회수수 중 슬러지 고형성분의 혼입비율을 시멘트 중량의 3% 이하로 제한하고 있다. 따라서 본 연구에서는 규정이상의 슬러지 고형성분을 혼입한 경우, 콘크리트에 미치는 영향을 검토하였다. 실험결과에 따르면, 혼입율 증가에 따라 작업성은 떨어졌으나 강도발현은 좋게 나타났다. 또한 건조수축 및 동결융해 실험에서는 슬러지수 혼입에 따른 영향이 적은 것으로 나타났다.

• 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.

• 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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.888-895
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• 2000

As conventional grouting materials for the sheath such as cement slurry or cement-mortar are mixed and pumped in site, those harden with bleeding or shrinkage and meets low compressive strength. Also the materials haven't always same cements, sand size distributions, additives in site, so those materials have unstable quality properties. We have studies on ready-mixed-mortar for grouting pretensioned or post-tensioned cables and rods to encapsulate the steel so that we have developed a formulation of specially selected, flowable, shrinkage-compensating materials.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 추계 학술논문 발표대회
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• pp.149-150
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• 2018

The RC buildings which are constructed on the seaside are followed by KBC(2016) to achieve the minimization of durability damage. To control the corrosion of the reinforced steel bar by salt attack, W/C should be under 0.4 and specified concrete strength is more than 35MPa in the concrete/building construction standard specification. Ready mixed concretes which have usually include the admixtures in Busan were tested to certify the salt attack durability. In the same specified concrete strength, remarkable salt attack durability was evaluated in comparison to OPC.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.423-428
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• 1994

High strength concrete was placed at the mass concrete slabs, walls, pillars of RC building from August till August. And the construction is going on now. This paper presents mix design, production, quality control and experience with field application of high strength ready-mixed concrete under hot weathered conditions. It is shown to be possible to produce high strength concrete that has 45MPa compressive strength using superplasticizer and cement replaced with 20% fly-ash with appropriate control.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.117-118
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• 2022

High-strength concrete is used for building durability on the coast. It is common to order and produce the concrete from several ready mixed concrete companies. The concrete in Busan was also commissioned by 12 ready mixed concrete companies. The compressive strength and salt diffusion coefficient were measured. The average value and deviation were analyzed.