• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.67-73
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• 2011

In this study, it was investigated compressive strength generation of concrete using high volume mineral admixture obtaining fundamental data for the application of concrete structure in construction field. For this, it was evaluated compressive strength with unit binder contents($310{\sim}410kg/m^3$), replacement ratio of mineral admixture(70~90%), unit water contents($140{\sim}150kg/m^3$) and curing temperature in the normal strength range. Also, after producing mock-up structure, hydration heat and compressive strength generation was evaluated to examine properties in the concrete member. In case of concrete using a large amount of industrial byproducts which was reviewed in this study, it is possible to secure compressive strength more than 24MPa at age 28days with about $13^{\circ}C$ ambient temperature of curing condition and that is considered to be applied to structure at construction site.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.95-102
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• 2010

In recent years, the demand for the development of high quality and cost effective materials, as well as the competition to ensure a diverse and sufficient amount of ready-mixed concrete, has been increasing rapidly. In this experiment, concretes made with different admixtures are blended with each other in different combinations and ratios, in order to identify potential problems. The first test was a slump level test, in which all of the concretes met the required numbers, as they also did in the test for air content. Plain organic acid concrete scored the highest in bleeding amount, but organic acid mix in general showed a similar outcome. In the early measurement of compressive strength, plain naphthalene concrete was the strongest. Of the blends, the 5:5 mix of organic acid and naphthalene was the strongest. In the standard measurement, the 5:5 mix of naphthalene and lignin was the strongest. Tensile strength tests revealed similar results. Length change rate proved to be greater in blended concrete than in plain concrete, and dry shrinkage rate was highest in the 7:3 ratio blends. Through SEM photo analysis, it was confirmed that the 7:3 ratio blends contained more micro-voids. In conclusion, with the exception of a specific few combinations, it was found that the blending of different types of concrete is undesirable due to the delayed coagulation time as well as the early decrease in strength.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.435-444
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• 2012

High performance concrete mixes are selected and corresponding test specimens are made for the study of chloride diffusion coefficient at reference time. The concrete mixes were same designs as those used in construction of bridges located in a marine environment. Mix design variables included binder type, water-to-binder ratio, mineral admixtures to total binder weight substitution ratio, fine aggregate source, chemical water reducer admixture type for high strength and high flowability, and target slump or slump flow. The test results showed that the diffusion coefficients at reference time varied significantly according to the type of mineral admixtures and their substitution ratios. A model for diffusion coefficient at reference time considering the type of mineral admixture and the substitution ratio was developed. Diffusion coefficients from the developed model were compared with those from literature review, a previous model, and additional test results. All of the comparisons verified that the developed model can reasonably predict diffusion coefficients and the application of the model to the durability design against chloride penetration is appropriate.

• Magazine of the Korea Concrete Institute
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• v.9 no.1
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• pp.153-163
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• 1997

This paper is an experimental study of the chemical resistance of mortar which contains silica sand particles. The possible use of silica sand particles in the future as an admixture for improving chemical resistance of mortar is examined in mortar model experiments. The possibility of using mortar model its prediction models for the chemical resistance of concrete is examined. The results obtained are as follows. Since the experimental results from the chemical resistance tests based on the kinds and the amount of replaced admixture are similar to those from the concrete. mortar model could be used as a prediction model of chemical resistance of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.52-56
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• 1996

In this study, when natural mineral with Silica components(Zeolite & Mudstone) abundant in Korea used as an admixture for concrete, it is investigated that the properties of strength increase and economic effect compared with Silica Fume, the general admixture of high strength concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.16-25
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• 2018

Concrete is a suitable construction material for long-term structure, however, it is needed to understand the calcium leaching damage caused by exposure to underground pure water for a long time. In this paper, it is experimentally investigated that the characteristics of flexural behavior in RC member damaged by calcium leaching degradation. From the test results, when calcium leaching is happened, yielding load and flexural rigidity is reduced, neutral axis depth and displacement is increased. That is, calcium leaching degradation adversely affects RC member performance. And, when the mineral admixture is used in the calcium leaching environment, it is considered that the optimal replacement ratio should be prepared according to the type of mineral admixture.

• Magazine of the Korea Concrete Institute
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• v.9 no.6
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• pp.217-223
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• 1997

재생콘크리트의 압축강도와 휨강도는 재생골재의 혼입량이 증가할수록 감소하였으며 플라이애쉬를 혼화재로 사용할 때 그 양이 증가할수록 재생콘크리트의 조기 압축강도는 떨어졌다. 골재원에 따른 압축강도는 재생골재의 혼입량이 적을수록, 양생기간이 길어질수록 증가하엿으나, 전반적으로 비슷한 강도변화의 경향을 보여주고 있다. 재생콘크리트의 휨강도 발현은 보통 콘크리트와 비슷하나, 휨강도에 대한 압축강도비는 보통 콘크리트에 비하여 낮았다. 재생콘크리트의 건조수축은 재생골재의 혼입량이 증가할수록 증가하였으며 , 특히 재령2주와3주사이에 건조수축량이 보통 콘크리트에 비해 월등히 높았다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.301-306
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• 2015

For the purpose of developing high performance marine concrete with improved crack resistance and durability, this analytical study aimed to estimate strength, hydration heat characteristics, and chloride attack resistance of concrete with mineral admixture. Ground granulated furnace slag and fly ash were considered for mineral admixture. The replacement of ground granulated furnace slag and fly ash considered in the analysis was in the range of 0~70% and 0~40 %, respectively. The analysis results indicated that both ground granulated furnace slag and fly ash decreased compressive strength, and the effect of adding ground granulated furnace slag on mitigation of hydration heat was limited whereas fly ash had an noticeable influence on it. It was also found that the replacement with ground granulated furnace slag enhanced the chloride attack resistance but fly ash deteriorated the resistance. From the analytical studies, It could be expected that a ternary blended cement composition with proper amount of ground granulated furnace slag and fly ash might be effective to control crack resistance as well as chloride attack resistance of marine concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.333-336
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• 2008

As the high-rise building increase due to the gravitation of population to big cities recently, it requires high quality and high performance of Concrete. As a result, people are keenly interested in Meta-kaolin as new admixture favorable from an economic perspective, which has strength and endurance with admixture at the same level like Silicafume. Accordingly, as to Meta-kaolin, this study was to set by three levels like domestic one, foreign one, and Silicafume, the waterbinding material ratio 25%, and four level substitute like 0, 10, 20, and 30(%) in order to compare and analyze the quality characteristics of high-strength concrete according to the substitute of Meta-kaolin applicable with replacement of Silicafume. As a result of performing experiment, as to the higher the additive amount of Superplasticizing agents in order to secure target liquidity was, the more the substitute in each admixture increased. This study had a tendency that the Silicafume increased the additive amount of Superplasticizing agents with high fineness compared with Meta-kaolin. In addition, the higher the substitute in each admixture was, the more its strength increased On the strength property, the higher the substitute in each admixture was, the more its strength increased. This study has found out that the Meta-kaolin has shown the better strength than the one of Silicafume. On the other hand, the relationship between the Compressive strength and Elastic coefficient has shown the similar formula suggested from ACI363.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.805-808
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• 2008

This study analyzed the basic characteristics of concretes to develop 3 ingredients high performance concrete that displaced BS and FA, and the results are as follows. As part of fresh concrete characteristics, the flow was shown more increase than OPC with increase in admixture material displacement rate, and air amount tended to decrease with increase in admixture displacement rate. As hardened concrete characteristics, compressive strength decreased below OPC at early age with increase in BS and FA displacement rate, however at age 28 days, it was similar to OPC or increased above that. Particularly, at B30F15 with age 28 days, its compressive strength was about 15% higher than OPC