• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.145-146
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• 2018

In this study, the purpose of the study is to determine the depth of damage caused by early frost damage in concrete slab structures under the conditions of external temperature during winter. In other words, we intend to analyze the depth variation of the early frost damage as the thickness of the normal strength concrete slab members changes. As a result, the thinner the component was, the deeper the early frost damage was found to be, and the resulting increase in brightness of the concrete was delayed. and It is analyzed that under this test condition, an early frost damage was created with a thickness of 50 mm for the member and a thickness of 39 mm for the member of 300 mm.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.65-66
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• 2017

Early-frost damages easily take place in smaller and thinner walls and slabs. In case of slabs, it is difficult to visually determine the depth of early-frost damage. As such, the current study aims to determine the depth of early-frost damage caused to concrete structures due to bad curing in the winter. As a result, the study found that the depth of early-frost damages increased from the top as the atmospheric temperature on the concrete surface decreased. The changes in the color allowed the observer to easily identify the depth of early-frost damage with the naked eye. In particular, the color difference between potentially damaged parts and undamaged parts were the greatest around thirty minutes of drying after wetting.

• Journal of the Korea Concrete Institute
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• v.12 no.3
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• pp.47-55
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• 2000

Protections from the frost damage at early ages are one of the serious problems to be considered in cold weather concreting. Frost damage at early ages brings about the harmful influences on the concrete structures such as surface cracks and declination of strength development. Therefore, in this paper, protecting periods of frost damage at early ages according to the standard specifications provided in KCI(Korean Concrete Institute) are suggested by appling logistic curve, which evaluates the strength development of concrete with maturity. W/B, kinds of cement and curing temperatures are selected as test parameters. According to the results, the estimation of strength development by logistic curve has a good agreement between calculated values and measured values. As W/B and compressive strength for protecting from frost damages at early ages increase, it is prolonged. It shows that the protecting periods of FAC(Fly Ash Cement) and BSC(Blast-furnace Slag Cement) concrete are longer than those of OPC(Ordinary Portland Cement) concrete. The protecting peridos from frost damage at early age by JASS are somewhat shorter than those by this paper.

• Nuclear Engineering and Technology
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• v.45 no.3
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• pp.393-400
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• 2013

Concrete undergoing early frost damage in cold weather will experience significant loss of not only strength, but also of permeability and durability. Accordingly, concrete codes like ACI-306R prescribe a minimum compressive strength and duration of curing to prevent frost damage at an early age and secure the quality of concrete. Such minimum compressive strength and duration of curing are mostly defined based on the strength development of concrete. However, concrete subjected to frost damage at early age may not show a consistent relationship between its strength and durability. Especially, since durability of concrete is of utmost importance in nuclear power plant structures, this relationship should be imperatively clarified. Therefore, this study verifies the feasibility of the minimum compressive strength specified in the codes like ACI-306R by evaluating the strength development and the durability preventing the frost damage of early age concrete for nuclear power plant. The results indicate that the value of 5 MPa specified by the concrete standards like ACI-306R as the minimum compressive strength to prevent the early frost damage is reasonable in terms of the strength development, but seems to be inappropriate in the viewpoint of the resistance to chloride ion penetration and freeze-thaw. Consequently, it is recommended to propose a minimum compressive strength preventing early frost damage in terms of not only the strength development, but also in terms of the durability to secure the quality of concrete for nuclear power plants in cold climates.

• Research in Plant Disease
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• v.29 no.3
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• pp.220-233
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• 2023

The phenomena of global warming has led to an increase in the average air temperature in temperate climates. Springtime frost damage is becoming more common, and after a period of dormancy, damage to buds, blooms, and developing fruits is greater significant than damage from low winter temperatures. Peaches are a crucial crop among moderate fruits. Spring frost damage in peaches can have a negative effect on crop growth, yield, and quality. It is noteworthy that these plants have evolved defenses against spring frost damage while being exposed to a variety of low temperatures in the early spring. In this current review, recent research advancements on spring frost damage avoidance in peaches were deliberated. Additionally, adaptive mechanisms of peach, such as deacclimation and reacclimation, were emphasized. Moreover, the emerging advancements using various omics approaches revealed the peach physiology and molecular mechanisms comprehensively. Furthermore, the use of chemical products and understanding the spring frost mechanisms through the use of environmental chamber temperature stimulation and infrared thermography studies were also discussed. This review is essential groundwork and paves the way to derive and design future research for agronomists and horticulturalists to overcome the challenges of spring frost damage avoidance and crop management in these circumstances.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.27-37
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• 2007

The purpose of this study is to propose a method to predict the minimum curing time of early age concrete required to prevent frost damage. Tests were performed to examine major factors, which affect the compressive strength of concrete frozen at early ages and investigate the source of frost damage at early age concrete. The results from the tests showed that the loss rate of compressive strength decreases as the beginning time of frost damage was delayed and water-cement ratio was lower. In addition, the test results also showed that concrete made with type III cement was less susceptible to frost damage than concrete made with ordinary Portland cement and frost damage occurred through the formation of ice lenses. When early age concrete is being damaged by frozen, a phase transition into ice of free water presented at the capillary pores of the concrete gives a reason for the decrease of compressive strength. Accordingly, the frost resistance of fresh concrete can be determined based on the saturation degree of the capillary pores. The method to predict the minimum curing time was suggested using the concept of critical saturation degree of the capillary pores.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.179-182
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• 1999

A protections from the frost damage at early ages is one of the serious problems to be considered in cold weather concreting. Frost damage at early ages brings about the harmful influences on the concrete structures such surface cracks and the loss of strength. Therefore, in this paper, the protecting durations of frost damage at early ages according to the standard specifications provided in KCI(Korean Concrete Institute) are suggested by appling logistic curve, which evaluates the strength development of concrete with maturity. According to the results, as W/C and compressive strength for protecting from frost damages at early ages increased, longer protecting duration is required. It shows that the protecting durations of FAC(Fly Ash Cement) are longer than those of OPC(Ordinary Portland Cement).

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.629-634
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• 2001

Recently, to consider financial and constructive aspect, usage of Admixture, like Blast-Furnace Slag and Fly-Ash, are increased. Also the use of cold-weather-concrete is increased. Blast-furnace Slag, a by-product of steel industry, have many advantage, to reduce the heat of hydration, increase in ultimate strength and etc. But it also reduces early-age strength, so it is prevented from using of Blast-Furnace Slag at cold-weather-concrete. In this study, for the purpose of increasing usage of Blast-Furnace Slag at cold-weather-concrete, it is investigated the strength properties of concrete subjected to frost damage for the cause of early age curing. According to this study, if early curing is carried out before having frost damage, the strength of concrete, subjected to frost damage, is recovered. And that properties is not connected with the frost cause.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.143-148
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• 2002

Recently, to consider economical and constructive aspect, Usage of Admixture, like Blast-Furnace Slag and Fly-Ash, are increased. Blast-Furnace Slag, a by-product of steel industry, have many advantage, to reduce the heat of hydration, increase in ultimate strength and etc. But it also reduces early-age strength, it is prevented from using of Blast-Furnace Slag at cold-weather-concrete. In this study, for the purpose of increasing usage of Blast-Furnace Slag at cold-weather-concrete, it is investigated the strength properties of concrete subjected to time and period of frost damage for early age curing. According to this study, if early age curing is carried out before having frost damage, the strength of concrete, subjected to frost damage, is recovered. And that properties is not connected with the frost cause.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.207-208
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• 2017

The current study assumed a condition in which concrete curing was not completed correctly in the winter, in order to analyze the effect of changes in early low-temperatures in early-frost damage depth. As a result, lower external temperature early on after depositing the concrete greatly reduced the temperature in the upper parts of the concrete, and it delayed the time during which the concrete temperature restored. In addition, for early-frost damages, lower early temperature increased the expansion of frozen water, which in turn relaxes the concrete structures and increases the absorption rate, ultimately extending the depth of early-frost damage.