• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.46-47
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• 2018

High performance concrete with low water-to-cement ratio has been widely used with increased demand of high rising buildings and huge scaled structures. Additionally, for high performance concrete, various SCMs are replaced to improve its performance from fresh state to hardened state. With the drawback of increased viscosity of the concrete mixture for high performance concrete, low-viscosity typed high range water reducer is the relatively new admixture. Therefore, as a goal of the research, under using various SCMs with wide range of content, the performance of low-viscosity typed high range water reducer was evaluated. Especially, in this research, the influence of low-viscosity typed high range water reducer on rheological properties including plastic viscosity and yield stress were assessed. As a result of the research, it is expected to provide a fundamental information of low -viscosity typed high ranged water reducer on high performance concrete with various conditions of SCMs.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.997-1000
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• 2008

Strength development of concrete subjected to cold weather is generally delayed due to its low temperature. In case of soil nailing method, it is necessary to apply the shotcrete. However, the shotcrete placement under low temperature experiences retardation of strength development due to delayed hydration reaction. Therefore, in this paper, the use of fine particle cement which is produced through particle classification in cement manufacturing process, is discussed to enhance the strength development of the shotcrete under low temperature. According to the results, the concrete containing 100% of fine particle cement had excellent strength development even at $-9^{\circ}C$ of temperature and at 5days, it reached design strength with PE film curing. It is thought that more than 70% of fine particle cement can secure required strength of the shotcrete even at low temperature condition.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.505-508
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• 2008

In this study, temperature increase and strength development of concretes with different types of cement were investigated to construct dam drop spillway. For this purpose, boxes of 1${\times}$1${\times}$1m size with 4 different concrete mixtures were made. The types of concrete were Type I cement concrete, fly ash cement concrete and two type concrete with ternary cement, respectively. The temperature at each point were monitored in these boxes. Based on the Box test, hydration analysis of slab of 2.0m thickness was carried out. This paper presents these experimental and analytical results.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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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.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.79-84
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• 2001

Because the WFS(Waste Foundry Sand), by-product of a casting factory, is generally a smaller particle than a fine aggregate, it has a bad influence on quality of concrete. Especially, the grading of aggregate is a very important factor in the case of concrete-based products having low water cement ratio manufactured by vibration and pressing method. Therefore, it is necessary to use WFS with the suitable grading of aggregate that it don't has a bad Influence on the quality of concrete-based products. This study investigated the suitable using proportion of WFS by means of the composition method of aggregate suggested by Driscoll. The results showed that it was desirable to use 10% of WFS since higher strength was developed with that amount.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.291-296
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• 2000

The crack of concrete induced by the heat of hydration is s serious problem, particularly in concrete structures such as bridge piers. thick walls, box type walls, mat-slab of nuclear reactor building, dams of foundations of high rise buildings, etc. As a result of the temperature rise and restriction condition of foundation, the thermal stress which way induce the cracks can occur. Therefore the various techniques of the thermal stress control in massive concrete have been widely used. One of them is prediction of the thermal stress, besides low-heat cement which mitigates the temperature rise, design change which consider steel bar reinforcement, operation control and so on. In this study, firstly it introduce the thermal cracks control technique by employing low-heat cement concrete, thermal stress analysis, Secondly it shows the application of the cracks control technique like the bottom of No.15,16 Underground LNG Tank in Inchon.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.199-204
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• 2000

When fresh concrete is exposed to low temperature, the concrete may suffer from the frost damage at early ages and the strength development may be delayed. To solve such problems of cold weather concreting, admixtures called agent for enduring cold climate are developed to prevent the fresh concrete from being frozen at early ages In this study, the experiments are carried out on several kinds of agent for enduring cold climate to present their performance. According to experimental results, most kinds of agent for enduring cold climate show the satisfactory properties of decreasing the freezing point and acceleating the cement hydration in low temperature environment, which is available for placing concrete in spite of cold weather.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1181-1186
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• 2000

The crack of concrete induced by the heat of hydration is a serious problem, particularly in concrete structures such as biers, thick walls, box type walls, mat-slab of nuclear reactor buildings, dams or foundations of high rise buildings, etc.. As a result of the temperature rise and restriction condition of foundation, the thermal stress which may induce the cracks can occur. Therefore the various techniques of the thermal stress control in massive concrete have been widely used. One of them is prediction of the thermal stress, besides low-heat cement which mitigates the temperature rise, design change which considers steel bar reinforcement, operation control and so on. In this study, firstly it introduce the thermal cracks control technique by employing low-heat cement concrete, thermal stress analysis considering season. Secondly it shows the application of the cracks control technique like block placement.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.689-692
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• 2006

The crack of concrete induced by the heat of hydration is a serious problem, particularly in massive concrete structures. In order to control the temperature crack of massive concrete, the selection of appropriate materials like low heat cement, mixture materials, etc. is essential. In tills study, mix proportion using low heat portland cement and lime stone powder was designed and the best mix proportion, B-1, was selected. When bottom slab of the #219 LNG tank in Incheon was constructed, concrete temperature was measured. And thermal stress was analyzed about bottom slab of the LNG tank. As results of the thermal analysis, crack index was 1.60 in bottom slab and satisfied with construction specifications(over 1.0).

• Cement Symposium
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• s.49
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• pp.31-32
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• 2022

This study is to analyze the difference by comparing the physical properties of general Portland cement (OPC) and low-heat Portland cement (LHC) in the market to develop low-heat cement manufacturing technology that can minimize the amount of limestone by using non-carbonate circulating resources as raw materials. To this end, the mortar is being reviewed by evaluating the properties of the mortar, such as slump, strength, durability, and thermal insulation properties, with a difference in the mixing ratio.