• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.183-188
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• 1997

From a viewpoint of construction cost and preserving management of pavement, a policy of domestic pavement was gradually spreaded concrete pavement rather than asphalt. But the use of concrete with ordinary portland cement has shortages, such as dry-shrinkage, low flexural strength, etc. In order to overcome these problems, the concrete pavement using CSA expansive additive (Non-Shrinkage Cement) was studied and carried out the fie이 application. As the results, we find out Non-Shrinkage Cement that was distinguished in short-term construction by increasing flexural strength, shrinkage compensating and low-heat evaluation compared with OPC concrete.

• 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.

• Advances in concrete construction
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• v.5 no.1
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• pp.17-29
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• 2017

Geopolymer concrete is environmentally friendly and could be considered as a construction material to promote the sustainable development. In this paper fly ash based geopolymer concretes with different percentages of alccofine were made by mixing sodium hydroxide and sodium silicate as an alkaline activator and cured at ambient as well as heat environment in an electric oven at $90^{\circ}C$. Effects of various parameters such as the percentage of alccofine, curing temperature, a period of curing, fly ash content, was studied on compressive strength as well as workability of geopolymer concrete. The study concludes that the presence of alccofine improves the properties of geopolymer concrete during a fresh and hardened state of concrete. Geopolymer concrete in the presence of alccofine can be used for the general purpose of concrete as required compressive strength can be achieved even at ambient temperature. The 28 days compressive strength of 73 MPa, when cured at 90-degree Celsius, confirmed that it is also very suitable for precast concrete components.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.83-85
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• 2011

This study investigated the results of insulation heat curing method using double layer bubble sheet in concrete in cold weather environment. First of all, when double bubble sheets are applied, it was shown that concrete was protected from early freezing by remaining between 7℃ and 3℃ even in case outside temperature drops -7℃ below zero until the 3d day from piling. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.25-28
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• 2009

This study investigated the results of insulation heat curing method using double layer bubble sheet in slab concrete in cold weather environment. First of all, when double bubble sheets are applied, it was shown that slab concrete was protected from early freezing by remaining between 5 and $l0^{\circ}C$ even in case outside temperature drops $-11^{\circ}C$ below zero until the 4nd day from piling. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.6 s.107
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• pp.82-94
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• 2005

This study was undertaken to measure and analyze the thermal environment characteristics of the grey permeable cement concrete pavement(GPCCP), the permeable cement concrete brick pavement(PCCBP) compared with impermeable cement concrete pavement(ICCP) and bare soil(BS) under the summer outdoor environment. Following is a summary of major results. 1) The peak surface temperature was greatest in the GPCCP$(54.2^{\circ}C)$ followed by ICCP$(47.2^{\circ}C)$ rut August 2, 2002, the hottest day$(35.3^{\circ}C\;of\;highest\;temperature)$ during the experiment; peak temperature in the ICCP and BS were $45.5^{\circ}C)$ and $45.3^{\circ}C)$ respectively. 2) Analysis of heat budget of the pavements has revealed that the heat environment was worse in the GPCCP than that in the ICCP and that this was mainly due to a low albedo in the former(0.2) relative to that of the latter(0.4). 3) Analysis of heat budget of the pavements has revealed that the heat environment was worse in the GPCCP than that in the PCCBP, BS and that this was mainly due to a decreased latent heat resulting from a time dependent decreasing impact of rainfall. 4) It is necessary to make cool pavements to further studies on light-colored surface materials for attaining high albdo and construction methods which can enhance the latent heat through the continuous evaporation from pavements surface. 5) Vertical arrangement of pavement layers has not been considered in the present study, which has been focuses on the heat characteristics of the surface layer materials. Accordingly, future studies will have to be empasized on pavement methods including the vertical arrangement of the pavement layers.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.48-51
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• 1996

Recently, frost damage of storage tank for admixture agent caused by low temperature in winter and quality deterioration of admixture agent ofen happened. But, many problems are caused because of no applicable regulations of admixture agent facility and so on. Therefore, this study presents the reference data about using and quality control of admixture agent in practice and the judgement data about working out a counter plan of suitable heat insulation of injecion equipment of admixture agent exposed at outside in winter by measuring the freezing point of admixture agent for concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.373-378
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• 1996

This paper presents the characteristics of various strengths of underwater non-segregation concrete. Three types of cements including low-heat cements has been used to make the test specimens for compressive strength, modulus of rupture and bond strength. The test specimens have been made both in ambient and underwater conditions to take into account the variation according to the environmental condition.

• Journal of the Korea Institute of Building Construction
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• v.9 no.3
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• pp.95-101
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• 2009

Constructing large-scale mat foundation mass concrete is increasing for the stability of building structure, because a lot of high rise building are being built in order to make full use of limited space. However, It is of increasing concerns that because limited placing equipments, available job-site and systems for mass concete placement in construction field do not allow to place great quantity of concrete at the same time in large scale mat foundation, consistency between placement lift can not be secured. And also, it is likely to crack due to stress caused by the difference of hydration heat generation time. To find out the solution against above problems, this study is to reconfirm the performance of normal concrete designed by mix proportion and super retarding concrete. The Fundamental test shows what happens if low heat proportioning and control method of setting time are applied at the job-site of newly constructed high rise building. The test result show that slump flow of concrete has been somewhat increased as the target retarding time gets longer, while the air content has been slightly decreased but this is no great difference from normal concrete. The setting time shows to be retarded as target retarding time gets longer, the range of retarding time increases. It is necessary to increase the amount of mix of super retarding agent in the proportion ration by setting curing temperature high since outdoor curing is about 6 hours faster than standard curing, which means the temperature of the concrete will be higher than the temperature of the surrounding environment, due to its high hydration heat when applying in a construction site. The compressive strength of super retarding concrete appears to be lower than normal concrete due to the retarding action in the early stage. However, as the time goes by, the compressive strength gets higher, and by the 28th day the strength becomes the same or higher than normal concrete.

• International Journal of High-Rise Buildings
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• v.5 no.3
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• pp.205-211
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• 2016

This paper addresses the key technologies for supertall building construction based on the Lotte World Tower project in Korea. First, the mega-mat foundation construction technologies are shown, including ultra-low heat concrete, heat of hydration control programs, and the logistics plan. Then, high strength concrete technologies of 50~80 MPa are introduced and discussed within the context of the highest pumping record in Korea at 514.25 meters. Structural design concepts of gravity load and lateral force resistance systems are introduced, along with surveying systems using GNSS and temporary installation plans of special heavy equipment like tower cranes, hoists, and high pressure concrete pumps. If it is possible to coordinate these key technologies and others, optimizing for the building's design and construction, supertall building construction can be successfully completed.