• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.3
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• pp.141-148
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• 2004

This paper present the experimental research investigating the influence of material factors such as a type or amount of superplasticizer, velocity agent, mineral admixture and steel fiber on the workability of high strength steel fiber reinforced cementitious composites. As for the test results, it was found that the workability of high strength steel fiber reinforced cementitious composites can be improved when the material factors were matched properly in amount and composition. Furthermore, it was shown that the smaller value of the aspect ratio of steel fiber improved the workability of fiber reinforced cementitious composites. And the steel fiber reinforced cementitious composites with better workability showed the enhanced compressive strength and flexural strength.

• 레미콘
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• no.6 s.12
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• pp.2-10
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• 1987

• Journal of the Korean Ceramic Society
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• v.13 no.3
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• pp.37-42
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• 1976

Although the water mixed into the concrete plays the role of hydration and acquiring the necessary workability, the more portion of water acts to obtain the substantial workability rather than to complete the hydration. However, the excess amount of water causes the poor quality of concrete, therefore it is useful to add the minimum amount of water as required as to acquire the proper workability. There have been the considerable numbers of investigations in which the dispersion phenomena of strong eletrolytic high polymer compounds such as lignosulfate and some of surface activation agents were studied to utilize as the dispersion agent of concrete. In the present study, Na-lignate, dispersion properties of which has not been studied yet, were investigated with the purpose of utilizing as a dispersion agent of concrete. The microscopic observations showed a great improvement in the dispersion of cement particles, also the fluidity and compressive strength of concrete were remarkably increased with the addition of Na-lignate: The addition of Na-lignate by 0.02% showed the increase of 1.76 times and 1.27 times of slump value and flow value respectively, and the compressive strength was increased by 1.07 times.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.3
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• pp.50-58
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• 2003

Due to the economic growth and the improvement of life standards in the country, the quantities of waste glasses have been yearly increased. About 65% of them are recycled and the rest are reclaimed. The reclaimed waste glasses can cause some problems such as the environmental pollution as well as the processing cost of them. Thus, the purpose of this experimental research is to investigate the properties of mortar using powdered waste glasses(PWG) as a cementitious materials in mortar to recycle the reclaimed waste glasses For this purpose, the workability and strength of mortar specimens using PWG have been tested and analyzed in various grain size of them by changing the replacement ratio. As a result, considering the workability and strength of mortar specimens using PWG, it is concluded that the optimum grain size and replacement ratio of them will be existing.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.205-206
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• 2014

It is very important to reduce the construction duration of the Reactor Containment Building (RCB) when considering the more than 50 months on average from concrete placement to completion. The purpose of this study attempts to evaluate the single-stage workability of the system given a change in the height of the setting of RCB exterior wall formwork to be used in nuclear power plant construction. As a result of this study, it is possible height of 3.5m~4m uses formwork when analyzing the construction period and material costs an increase in formwork by concrete lateral pressure, to ensure the workability of the RCB exterior wall formwork. Through this study, I want to provide as basic data for the improvement of workability and RCB shortening the construction period.

• 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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• 2006.05b
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• pp.393-396
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• 2006

This study present the experimental research investigating the influence of material factors such as a type or amount of superplasticizer, velocity agent, mineral admixture and steel fiber on the construction performance of fiber reinforced cementitious composites. As for the test results, it was found that the workability of fiber reinforced cementitious composites can be improved when the material factors were matched properly in amount and composition. Furthermore, it was shown that the smaller value of the aspect ratio of fiber improved the workability of fiber reinforced cementitious composites. And the fiber reinforced cementitious composites with better workability showed the enhanced compressive strength and flexural strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.53-56
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• 2005

High flowable concrete was first developed in 1988 to achieve durable concrete structures. High flowable concrete can improve workability sharply reason why the concrete has properties of resistance to segregation, filling ability, passing ability without compacting. Therefore, as we apply a high flowable concrete to a large dimensional tunnel which constructed in special environment, we can get workability, strength and durability required. Tunnel lining concrete with a large dimension has to use necessarily fly ash and slag for the properties of high flowability and watertight. We can expect improvement of workability and durability, mitigation of hydration, reducing shrinkage, enhancement of watertight by using cementitious materials. This paper proposes investigations for establishing a mix-design method and high flowability-strength testing methods have been carried out from the viewpoint of making a standard concrete tunnel lining with large dimension a standard.

• Advances in concrete construction
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• v.15 no.6
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• pp.405-417
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• 2023

While ultra-high performance concrete (UHPC) is commonly reinforced with micro straight steel fibers in existing applications, studies have indicated that the use of deformed steel macro-fibers leads to enhanced ductility and post-peak responses for UHPC structural elements, which is of particular importance for earthquake-resistant structures. However, there are potential concerns regarding the use of UHPC reinforced with macro-fibers due to the issues of workability and fiber distribution. The objective of this study was to address these issues by extensively investigating the restricted and non-restricted deformability, filling ability, horizontal and vertical velocities, and passing ability of UHPC containing macro hooked-end steel fibers. A new approach is suggested to examine the homogeneity of fiber distribution in UHPC. The influences of ultra-fine fillers and steel macro-fibers on the workability of fresh UHPC and the mechanics of hardened UHPC were examined. It was found that although increasing the ratio of quartz powder to cement led to an improvement in the workability and tensile strain hardening behavior of UHPC, it reduced the fiber distribution homogeneity. The addition of 1% volume fraction of macro-fibers in UHPC improved workability, but reduced its compressive strength, which is contrary to the effect of micro-fiber inclusion in UHPC.

• Proceedings of the Korea Concrete Institute Conference
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• 1989.10a
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• pp.15-20
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• 1989

The effect of superplasticizing agents on the sorkability performance in fresh concrete have been analyzed and investigated under various mix proportions of water cement ratio of 0.40, 0.50, 0.60 and 0.70, superplasticizing agents of NL-4000 and Rheobuild-716, and addition rate of sp. agents of 0.0, 0.5, 1.0, 1.5 and 2.0 in the practical range. It is the aim of this study to provide the fundamental data on the fluidity performance and workability improvement of superplasticized concrete such as time-dependent change of slump, flow value and compacting factor, air content, bleeding, mixing temperature and setting rate of fresh concrete comparing with base concrete and conventional concrete for the practical use and research data accumulation of superplasticized concrete in the side of development of concrete construction technology and management.