• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.303-308
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• 2001

Recently, concrete structures have become larger and higher and are demanding high performance concrete with lower heat to prevent thermal cracking, far greater workability, high strength and durability, Application of low heat portland(Type IV) cement for the high performance concrete is the best solution to satisfied those requirements. Here are explained the effect on the properties of high flowing concrete using low heat portland cement by material and mixing variations. Variables for sensitivity test were selected items like finess modulus of aggregates, particle size of limestone powder, unit water, superplasticizer, viscosity agent and concrete temperature. The results of this study were be applied to slurry wall of #215 and #216 of underground LNG tank in Inchon.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.275-282
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• 2002

High fluidity concrete needs high dosage of superplasticizer to acquire sufficient fluidity and high contents of fine powder and viscosity agents to prevent segregation. But it requires high manufacturing cost and has difficult in quality control. Therefore, in this paper, determination of optimal mixture proportion of segregation type superplasticizer for high fluidity concrete and manufacturing high fluidity concrete by applying developed segregation reducing type superplasticizer are discussed using flowing concrete method. According to test results, as dosage of superplasticizer increases, it shows that fluidity and bleeding increase, while air contents and ratio of segregation resistance decrease. It also shows that adding viscosity agent into it reduce bleeding and improve segregation resistance. Dosage of AE agent into it containing viscosity agent recovers loss of air contents during flowing procedure. Combination of proper contents of superplasticizer, viscosity agent and AE agent make possible to develope segregation reducing type superplasticizer Compressive strength of high fluidity concrete applying flowing method with it is higher than that of base concrete. No differences of compressive strength between compacting methods are found.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.2
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• pp.34-41
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• 2011

Wrought nickel-base superalloys are being considered as the structural materials in very-high temperature gas-cooled reactors. To understand the effects of impurities, especially oxygen, in helium coolant on the mechanical properties of Alloy 617, creep tests were performed in high temperature flowing He environments with varying $O_2$ contents at 800, 900, and $1000^{\circ}C$. Also, creep life in static He was measured to simulate the pseudo-inert environment. Creep life was the longest in static He, while the shortest in flowing helium. In static He, impurities like $O_2$ and moisture were quickly consumed by oxidation in the early stage of creep test, which prevented further oxidation during creep test. Without oxidation, microstructural change detrimental to creep such as decarburization and internal oxidation were prevented, which resulted in longer creep life. On the other hand, in flowing He environment, surface oxides were not stable enough to act as diffusion barriers for oxidation. Therefore, extensive decarburization and internal oxidation under tensile load contributed to premature failure resulting in short creep life. Limited test in flowing He+200ppm $O_2$ resulted in even shorter creep life. The oxidation samples showed extensive spallation which resulted in severe decarburization and internal oxidation in those environments. Further test and analysis are underway to clarify the relationship between oxidation and creep resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.369-372
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• 2008

In this research experimentally analyzes the flow characteristics of a combined High flowing Self-Compacting Concrete of which the viscosity agent and defoaming agent addition amount are changed, to make the combined High flowing Self-Compacting Concrete that can secure the required flow performance and air amount. As a result of the experiment, the slump flow of the combined High flowing Self-Compacting Concrete added with viscosity agent increases when the viscosity agent addition amount is 0.2%(${\times}$W %). When viscosity agent addition amount increases, viscosity agent shows that it largely deviates from the regulation value in the flow time of V-funnel, which is presented in the JSCE standards (grade 2). Also, all mixtures, except for mixtures added with viscosity agent, defoaming agent, and AE agent, do not meet a target air amount $4.5{\pm}1.5%$. High flowing Self-Compacting Concrete mixtureadded with defoaming agent shows that although time passes after its first mixture, its air amount reduces a little. Based on the experiment, we can know an optimal polymer amount to obtain the required flow performance

• Advances in concrete construction
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• v.8 no.1
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• pp.65-76
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• 2019

This paper investigates the effect of recycled glass powder (RGP) on flowing properties of self-compacting mortars (SCMs) containing different ratios of fillers and superplasticizer dosages. Fly ash (FA), nano-silica (NS), micro-silica (MS), metakaolin (MK) and rice husk ash (RHA) are used as fillers and their synergistic effect with RFP is studied. The effects of fillers and high-range water reducer (HRWR) on flowing ability of mortars are primarily determined by slump flow and V-funnel flow time tests. The results showed that for composites with a higher RGP content, the mortar flowing ability increased but tended to decrease when the composites containing 10% MK or 5% RHA. However, the flowing ability of samples incorporating 5% RGP and 10% SF or 25% FA showed an opposite result that their slump flow spread decreased and then increased with increasing RGP content. For specimens with 3% NS, the influence of RGP content on flowing properties was not significant. Except RHA and MS, the fillers studied in this paper could reduce the dosage of HRWR required for achieving the same followability. Also, the mixture parameters were determined and indicated that the flowability of mixtures was also affected by the content of sand and specific surface area of cement materials. It is believed that excess fine particles provided ball-bearing effect, which could facilitate the movement of coarse particles and alleviate the interlocking action among particles. Also, it can be concluded that using fillers in conjunction with RGP as cementitious materials can reduce the material costs of SCM significantly.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.161-166
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• 1994

Production of high strength concrete requires a low water-cement ratio and this leads to the high cement content. Mineral admixture like fly ash(FA) is often cheaper than ordinary portland cement(OPC) and this factor in combination with possible improvement in workability and moderation of the heat evolution of the cement-rich mixes tends to encourage its use. The other mineral admixture that its use has been widly advocated is silica fume that increases compressive strength due to its pozzolanic reaction. The objective of this study is to assess the contribution of mineral admixtures(FA, SF) to the workability and the strength of concrete with low water-binder ratios. In this experimental study that investigates and analyzes the properties of fresh concrete, it is presented that using admixtures like flysh and silica fume as binding material increases properties of high strength flowing concrete having very low water cementitious ratios of 0.25 and 0.30.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.84-87
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• 1995

Production of high strength concrete requires a low water-cement ratio and this leads to the high cement content. Mineral admixture like fly ash(FA) is often cheaper than ordinary portland cement(OPC) and this factor in combination with possible improvement in workability and moderation of the heat evolution of the cement-rich mixes tends to encourage its use. The other mineral admisture that its use has been widly advocated is silica fume that increases compressive strength due to its pozzolanic reaction. The objective of this study is to assess the contribution of mineral admixtures(FA, SF) to the workability and the strength of concrete with low water-binder ratios. In this experimental study that investigates and analyzes the properties of fresh concrete. it is presented that using admixtures like flyash and silica fume as binding material increases properties of high strength flowing concrete having very low water cementitious ratios of 0.25 and 0.30.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.36-41
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• 1995

Recently, as the problems according to the deteriorated structure were gathering sterength, there were required the advent of the high peformance for polymer ceme at compostie in building constrution devision. The polymer cement mortar was developed for improvements of the various problems in ordinary cement mortar. finishing method using the super flowing polymer-based self levelling mortar for concrete slab and floor.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.402-407
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• 1996

In this paper, we described the basic elements(flowability, fillingability, elapsed time, pumpability, no-vibrating effects, and etc.) required for the application and quality control of the super flowing concrete (SFC) in construction site. Also, after investigating characteristics of SFC through various experiments, SFC were placed in the reaction wall of large scale structural laboratory in Deawoo Insititute of Construction Technology. As the result of this project, the developed SFC showed high flowability and self-filingability good enough for the requirement. Furthermore, quality control and assurance of the no-vibrating concrete in actual site was verified by various testing.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.83-88
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• 1997

In this paper, we described the basic elements (relative flowing area ratio and funeling velocity ratio in mortar, flowability and self-compactibility in concrete, and etc.) required for the maximum mix design of the super flowing concrete (SFC) using manufactured sand. Also, manufactured sand and fly ash were used for investigating characteristics of SFC through various experiments (replacement ratio of manufactured sand, optimum mix condition) before producing the concrete in batch plant. As the result of this project, the SFC using manufactured sand up to 50% showed high flowability and self-compactibility in fresh concrete. Furthermore, its compressive strength is higher than normal concrete without manufactured sand. From now on, this study may suggest how to apply manufactured sand in the SFC.