• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.117-127
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• 1999

In concrete incorporating high volume ground granulated blast-furnace slag that has frozen at early age, to evaluated the results of resistance to freezing and thawing is very difficult because the hydration of the concrete increases over the duration of rapid freezing and thawing test. Hence, the dynamic modulus of elasticity of specimens after freezing and thawing will be favorable results unless the hydration effect is taken into consideration. In this study, a method of evaluating to the resistance to freezing and thawing of concrete subjected freezing at early age, in which the effect of hydration is modified for its increase during rapid freezing and thawing test, is investigated.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.5
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• pp.527-534
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• 1997

Freezing of an aqueous sodium cWoride solution (Nacl- H20) saturating a packed bed with ini¬tial salt concentrations of 5, 10, 15(k by weight is investigated experimentally in a rectangular cav¬ity. The system was cooled from the top, bottom and a vertical side wall. For the freezing experi¬ments from below, there was little effect of the initial salt concentration throughout the freezing process, and the global freezing rate was not affected by the initial salt concentration. For the freezing from above, the size of the mush region decreased and the mushlliquid interface became flatter as the initial liquid concentration is decreased. For the freezing from vertical side wall, reheating of the mixture was intensified with an increase in the initial salt concentration. For Ci= 5%, supercooling was observed only at the early times of freezing process, but for Ci= 15% small supercooling was observed throughout the freezing process.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.533-536
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• 2001

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. One of the solution methods for resolving these problems is to reduce freezing temperature of concrete by the use of chemical admixture called Accelerators for freezing resistance. In this study, we investigate the effect on strength development of cement mortar using accelerators for freezing resistance with the variance curing condition. As the result of this study, the mortar using accelerators for freezing resistance show that continuously strength development in curing condition of -5$^{\circ}C$. And compressive strength under the variance temperature condition was higher than fixed temperature condition in same maturity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.6
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• pp.984-989
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• 1995

The concentration-efficiencyh of blue dextran solution in the progressive freeze-concentration was related to the freezing conditions such as the freezing speed and the stirring speed in the solution phase. From the theoreticla balance equation of heat and mass transfer at freezing front, the relationship between the freezing conditions and the ice structure at freezing front was drived. A high freeze-concentration efficiency was obtained under the operating conditions represented by a low speed of freezing and a high speed of stirring. The operating conditions were related to a smooth solid-liquid interface and these results were well explained by the theoretical equation. Effect of the solute component size on the concentration efficiency in the progressive freezeconcentration was also tested. The concentration efficiency of latex particles showed a lower value than that of blue dextran, however, its difference was insignificant.

• Geomechanics and Engineering
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• v.23 no.2
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• pp.179-187
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• 2020

Freezing-thawing cycles have significant effect on soils engineering behavior in frozen areas. This effect is more considerable in fine-graded than coarse-grained soils. The objective of this study is improving soil durability and strength in continues freezing-thawing cycles. For getting this purpose mixture of Polyvinyl Acetate (PVAc) and Ethylene Glycol Monobutyl Ether (EGBE) has been added to fine-grained soil and final prepared samples were tested at different freezing-thawing cycles. PVAc was mixed with 1%, 2% and 3% of soil weight. Half of PVAc weight was used as weight of EGBE. Freezing-Thawing cycles were exposed to samples and they were tested at different cycles. Results showed that adding mixture of PVAc+EGBE improved strength and durability of samples up to 10 freezing-thawing cycles. Unconfined compress strength tests were applied to samples and stress and strain of samples were tested on failure time. Behavior of samples was different at different percentages of mixture. Results showed that increasing amount of PVAc from 1% to 2% had more considerable effect on final stress than 2% to 3%. Using higher percentages of PVAc + EGBE mixture leaded to that samples carried more strain before collapsing. Another result gained from tests was that, freezing-thawing effect was more considerable after fourth cycles. It means differences between first and fourth cycles were more considerable than differences between fourth and tenth.

• Geomechanics and Engineering
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• v.24 no.6
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• pp.531-543
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• 2021

Freezing and thawing of pore water within backfill can affect the stability of retaining wall as the phase change of pore water causes changes in the mechanical characteristics of backfill material. In this study, the effects of freezing and thawing on the mechanical performance of retaining wall with granular backfill were investigated for various temperature and groundwater level (GWL) conditions. The thermal and mechanical finite element analyses were performed by assigning the coefficient of lateral earth pressure according to phase change of soil for at-rest, active and passive stress states. For the at-rest condition, the mobilized lateral stress and overturning moment changed markedly during freezing and thawing. Active-state displacements for the thawed condition were larger than for the unfrozen condition whereas the effect of freezing and thawing was small for the passive condition. GWL affected significantly the lateral force and overturning moment (Mo) acting on the wall during freezing and thawing, indicating that the reduction of safety margin and wall collapse due to freezing and thawing can occur in sudden, unexpected patterns. The beneficial effect of an insulation layer between the retaining wall and the backfill in reducing the heat conduction from the wall face was also investigated and presented.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.144-150
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• 2018

In this study, the freezing process of L-shaped pipe exposed to the outside was investigated numerically by considering the mushy zone of freezing water. From the numerical results, it was found that the flow was outwardly directed due to the influence of the L-shaped bending part in the outside exposed part of the pipe, and the ice was formed in the shape of longitudinal corrugation on the wall surface of the pipe after the bending part. It is confirmed that this phenomenon is caused by the venturi effect due to the freezing as seen in connection with the velocity distribution in the pipe. It is found that the remelting phenomenon at the end of the freezing section occur simultaneously during the process of forming the ice in the pipe section. In regard of the factors affecting freezing, it was found that the thickness of the freezing layer is increased as the exposed pipe surface temperature is decreased, and the pipe surface temperature had a significant effect on the change of the freezing layer thickness. At the same time, it was found that the freezing layer becomes relatively thin when the water inflow rate is increased. This phenomenon was caused by reducing the exposure time of freezing water due to the vigorous flow convection of the water fluid.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.3
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• pp.175-178
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• 2004

We here report that the muscle of 'gukmeri-bok' puffer fish (Takifugu vermicularis radiatus) is intoxicated after freezing and thawing processes even though it is not toxic when it is fresh. This study was carried out to investigate the effect of different freezing and thawing conditions as well as the effect of the presence of skin or viscera on the intoxication of muscle of 'gukmeri-bok' puffer during freezing and thawing process. As a result of this investigation, thawing condition, but not freezing conditions or periods played an important role in muscle intoxication. Tetrodotoxin secretory grands exist in the skin of toxic puffer fish, the skin was more responsible for the muscles intoxication than the viscera during the freezing-thawing process. In other words, no toxicity was measured in the muscle of skinned-frozen specimens even when thawed. According to this result, it is recommended that the skin and viscera must be removed before being frozen for edible purpose. Otherwise, when a whole fish should be frozen, alternative half-thawing and removal of skin from frozen specimens is recommended.

• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.128-133
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• 2001

It is generally known that the concrete structure subjected to severe environment is much affected by the corrosion of reinforcement, the freezing and thawing action of concrete structure. The main objective of this study is to investigate the freezing and thawing resistance of concrete including fly ash. The effect of the air content in concrete using fly ash is investigated. The experimental study is conducted for 10 mix-ratio cases of concrete of which variables are content of fly ash, concrete compressive strength and containment of air-entrained admixtures. Test results show that the freezing and thawing resistance improves as the amounts of fly ash increase, and concrete with air-entrained admixtures has good freezing and thawing resistance. The concrete with fly ash is to be included air-entrained admixture according to content of fly ash in order to increase the freezing and thawing resistance.

• Journal of the Korea Institute of Building Construction
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• v.2 no.2
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• pp.151-156
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• 2002

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. One of the solution methods for resolve these problems is to reduce freezing temperature of concrete by the use of chemical admixture called Accelerators for freezing resistance. In this study, we investigate the effect on strength development of cement mortar using accelerators for freezing resistance with the variance curing condition. As the result of this study, the mortar using accelerators for freezing resistance show that continuously strength development in curing condition of -5$^{\circ}C$. And compressive strength under the variance temperature condition was higher than constant temperature condition in same maturity.