• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.71-72
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• 2014

Green Frame is a building frame system to construct a column-beam structure using composite precast concrete members. To reduce the cost of producing precast concrete, in-situ production of members is required. However, when the structural members are produced on site, it needs a large space for production. So, "Just-In-Time" production method should be adopted. For Just-In-Time to be realized, the early strength of members should be ensured for them to be transported. Thus, steam curing to secure the early strength is applied in Green Frame. Yet, a large-scale steam curing system is not possible for in-situ production of precast concrete. A smaller steam curing system is needed. In this regard, the study is aimed to develop a new steam curing method applicable to the in-situ production of precast concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.63-71
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• 2010

This paper is about a research of steam curing which is one of the curing methods for accelerating the early-age strength of pre-cast concrete. With cylinder mold and mock-up specimen, the research was executed to study the best cycle of steam curing temperature through quantifying cycle of steam curing and maximum temperature, while the required strength is developed under the early-age. Moreover, causes and measurements for the high temperature of concrete, which is due to the steam curing, and the crack, which occurs when removing steel form, are stated. Ultimately, the economical method of producing, which satisfies early-age strength development and quality assurance while manufacturing PC structure, is stated.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.194-199
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• 1994

Frefab Construction known for durable construction skill prompting high productivity in developed country is not yet settled in Korea. This situation of prefab construction results from lack of skill, specialists and quality control. In introducing skill, all equipments are thoughtlessly imported without inside eudeavor for development. Regardless of production of goods, basic study for production of goods, construction and structure is not abailable. The object of this study is curing method in the production process of PC concrete product. From change of curing temperature and curing period which would be factors of product quality in PC concrete production, and research of optimized steam curing condition from relations between curing condition and strength development, basic data of concrete steam curing method will be presented.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.17-24
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• 2008

Many problems exist in the current cast in place concrete lining used in domestic tunnel construction. Especially, the crack of tunnel lining brings about a social and economic problem. It has a lot of influence on stability of structure and the fine finish of lining. So enormous repair-work and reinforcement of tunnel lining could occur an running out of government's budget. In our country, there are domestic production enterprises which produce a special pre-cast concrete product, but the technical level of them is still far behind compared to developed countries. Also, optimum steam coring method is important for the production of high quality product. But there is no regulation of steam curing method in our country. This study is to investigate the properties of PC panel according to the variation of steam curing conditions such as presteaming time and rate of temperature rise. The result shows that the optimum presteaming time of steam curing method in PC panel is more than 1 hour and the desirable rate of temperature in curing chamber is about $20^{\circ}C/hr$.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.11-14
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• 2004

The object of this study is vibrating compaction and curing method in the production process of Design concrete for precast concrete(Design-PC) product. From change of vibrating compaction time and pre-curing time. curing temperature which would be factors of product quality in Design-PC concrete production. and research of optimized steam curing condition from relations between curing condition and strength development. basic data of vibrating compaction time and concrete steam curing method for Design-PC will be presented.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.141-148
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• 2017

This study is experimentally investigated the effects of various steam curing parameters on the early-age compressive strength development of high strength concrete (over 40 MPa) in the precast plant production. High strength concrete are used only ordinary portland cement (type I) and water-cement ratio selected 3cases (25%, 35% and 45%). Also, steam curing parameters are as followings ; (1) Preset period 2cases (3 hours and 6 hours) (2) Maximum curing temperature 3cases ($45^{\circ}C$, $55^{\circ}C$ and $65^{\circ}C$) (3) Maintenance time of curing temperature 3cases (4 hours, 6 hours and 8 hours) (4) Maximum rate of heating and cooling $15^{\circ}C$/hr. Initial setting time and adiabatic temperature rising ratio of these concrete according to water-cement ratio are tested before main tests and examined the compressive strength development for the steam curing parameters. Also compressive strength are compared with optimum steam curing condition and standard curing at test ages. As test results, the optimum steam curing conditions for high strength concrete(over 40 MPa) are as followings. (1) Preset period ; over initial setting time of concrete (2) Maximum curing temperature ; bellow $55^{\circ}C$ (3) Maintenance time of curing temperature ; bellow 6hours. Also strength development of steam curing concrete show in the reversed strength at 28 days. It is to propose an efficient steam curing condition for high strength concrete in the precast method.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.161-164
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• 2004

The object of this study is vibrating compaction and curing method in the production process of Design concrete for precast concrete(Design-PC) product. From change of vibrating compaction time and pre-curing time, curing temperature which would be factors of product quality in Design-PC concrete production, and research of optimized steam curing condition from relations between curing condition and strength development, basic data of vibrating compaction time and concrete steam curing method for Design-PC will be presented.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.543-548
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• 2008

Solid hydrated by hydro-thermal synthesis reaction is cured two times, the first curing is the steam curing at atmospheric pressure and the second one is a high-pressure steam curing, that is autoclaving. Steam curing is to acquire the proper strength for the resistance of treatment in the first curing process, it was not evaluated properly so far. Because of ignorance about curing, some engineers even think that the dry curing is better than the steam curing. The relation between compressive strength of solid hydrated by hydrothermal synthesis reaction and curing condition are presented in this paper. In order to investigate the effect of curing on the strength properties of specimen, the hydration behavior of solid hydrated by hydro-thermal synthesis reaction has been studied over curing condition using XRD, DT-TGA and porosimeter, SEM analysis technique. The results show that the specimens which are cured with blended method of dry and steam curing appear to have better strength properties than that of dry curing and steam curing. Also, there are significant difference of hydration behavior among curing condition in the solid hydrated by hydro-thermal synthesis reaction.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.545-548
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• 2006

This study has been carried out to examine the properties of concrete according to replacement ratio and curing method of fly ash, in order to increase utilization of it. As the result of experiments, the 7 days of early age strength presented around 20MPa, up to 20% of replacement ratio, which is almost the same strength as non-replacement. However, when the replacement ratio was 30%, the strength was decreased to 16MPa, as 20% reduction compared to the non-replacement condition. In 365 days of long term aging, the strength was 5% higher, up to 20% of the replacement ratio, due to the pozzolanic reaction of fly ash. When the replacement ratio was 30%, it presented similar strength development as the non-replacement condition. Steam curing and autoclave curing increased the short age strength, regardless of the replacement ratio of fly ash; however, they don't have an effect on increasing the 365 days of long term strength. Water curing showed high strength development after 28 days, 51.81MPa, which is around 30% higher than air curing, 38.9MPa, steam curing, 38.6MPa, and autoclave curing, 39MPa. Therefore, water curing was examined as one of the very effective curing methods for developing long term strength of concrete.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.439-446
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• 2018

The PHC pile has been increasingly used due to its implementation of the top-base method, which is advantageous in high penetration rate and bearing capacity reinforcement. Typically, when a PHC pile is manufactured, high-strength mixed materials are mainly used to enhance the compressive strength. However, recent studies have been conducted to utilize ground granulated blast-furnace slag (GGBS) in terms of economic efficiency. For this reason, this study manufactured PHC pile considering the replacement ratio and curing conditions of GGBS instead of high-strength mixed materials, and further investigated the engineering properties of the PHC pile. According to the experimental results, the compressive strength of GGBS-replaced PHC pile increased by steam curing, and particularly, PHC pile with 20% replacement of GGBS under $80^{\circ}C$ steam curing condition showed a compressive strength of approximately 84MPa. Furthermore, the experimental results confirmed that more hydration products were generated under the $80^{\circ}C$ steam curing condition than that under the $20^{\circ}C$ steam curing condition, which would affect the higher density of the PHC pile as well as the increase in the compressive strength.