• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.81-92
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• 2013

This paper presents the results of a numerical investigation into the behavior of retaining wall subject to cycles of freezing and thawing due to seasonal temperature change. The thermo-hydro-mechanical coupled finite element modeling strategy was first established to simulate the wall behavior. A series of finite element analyses were then performed on a range of conditions representing seasonal temperature change characteristics. The results indicated that the average freezing temperature and the number of cycles of freezing and thawing were the primary influencing factors for the wall behavior. Also revealed was that the duration of freezing period does not significantly affect the wall displacement and the lateral earth pressure, and that the earth pressure on the wall does not significantly change due to the freezing and thawing action suggesting that the increase in the wall displacement during the freezing and thawing action may be attributed to degradation of backfill due to the freezing and thawing action.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.143-151
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• 2007

This study presents the experimental results of frost durability including resistance to freezing-thawing and surface scaling of concrete. Mixing design was proportioned with the various water-binder ratio between 0.37 and 0.47 and three different binder compositions corresponding to Type I cement without any supplementary cementitious materials(OPC), Type II cement with 50% blast-furnace slag replacement(BFS50), and ternary cement with Type III cement, 15% fly ash, and 35% slag replacement (BFS35%+FA15%). Test results showed that the mixing design with BFS50% and BFS35%+FA15% exhibited higher durability factor than that made with OPC only. Finally, the use of blend cement containing slag can be used effectively in terms of frost durability of the concrete exposed to severe condition under coastal environment like as flying salt, sea water spray, etc.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.56-64
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• 2021

Leakage due to deterioration and damage is one of the major causes of volume change by freezing and thawing, and it leads micro-cracking and surface scaling in concrete structures. The deterioration of damaged concrete accelerates with the chloride attack. Thus, in the detailed guidelines for facility performance evaluation (2020), the quality of cover concrete and the freeze-thaw (FT) repetition cycle were newly suggested for concrete durability assessment. The quality of cover concrete should be evaluated by the rebound hammer test and the FT repetition cycle should be also considered in the deterioration environmental assessment. This study suggested the application of fast dynamic based nonlinear ultrasound method to monitor initial micro-scale damage under freezing and thawing environment. Concrete specimens were fabricated with different water-cement ratios (40%, 60%) and air contents (1.5% and 3.0%). The compressive strength, rebound number, relative dynamic modulus, and nonlinear ultrasound were measured with different FT cycles. The scanning electron microscopy was also performed to investigate the micro-scale FT damage. As a result, both the rebound number and the relative dynamic modulus had difficulty to detect early damage but the proposed method showed a potential to detect initial micro-scale damage and predict the FT resistance performance of concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.161-168
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• 2008

The freeze-thaw deterioration and chloride attack, which are the typical degradation factors for durability of marine concrete, are significantly affected by pore structures in terms of penetration and diffusion. These pore structures of concrete are closely related to the types and amount of AE agent, used to guarantee the resistance of freeze-thaw deterioration, and the elapsed time before concrete pouring. This paper evaluates the durability of concrete based on the results of tests on cylinder specimens and core specimens from mock-up members with different air content of 4~6% and 8~10%, respectively. According to the test results, the air content of hardened concrete is 2.5~5.2% at 7 days and 2.4~5.1% at 28 days. These air contents are about half of the initial values just after the concrete mixing. Judging from the amount of scale after the freeze-thaw test completed, air content of 8~10% is slightly more beneficial against the deterioration of concrete than air content of 4~6%. Meanwhile, the core specimens from mock-up members exhibit somewhat unfavorable freeze-thaw deterioration and chloride migration characteristic compared with the cylinder specimens tested in the laboratory under the same mixing condition, as to show 106% in freeze-thaw test and 160% in chloride diffusion coefficient test, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.97-101
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• 2008

As the number of concrete building structures in marine environment increases, it is important to study and predict the durability and the compound deterioration of the concrete which is exposed in both chloride and freezing-thawing damage. The concrete's resistance against freezing and thawing is tested based on KS F 2456, while its chloride ion diffusion coefficient is evaluated based on NT BUILD 492. In result, the more exposure to freezing and thawing process, the shorter life it gets, due to the increased amount of chloride ion diffusion coefficient.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.137-139
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• 2007

Recently, the research on durability of concrete proceed rapidly in the building industry. Deterioration due to do-icing salts occurs in practice in bridge structure, dike, barrier and similar structure. This paper reports the results of effect of chlorides on the freeze-thaw properties of concrete bridge deck in winter. The case fresh water condition where the concrete will receives a freez-thaw effect compared to decrease of durability quotient a lot occurs is a possibility of knowing from brine condition.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3D
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• pp.325-330
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• 2008

This study carried out the repeated freezing-thawing test in order to understand the long-term degradation mechanism of GFRP dowel bars. The mechanical property measured by shear test. In addition, analyzes repeated freezing-thawing degradation mechanism of GFRP dowel bars by observe the microstructure through Scanning Electron Microscope (SEM) and Gas Physisorption techniques. As the result of test, it was found that the mechanical property didn't decreased as the exposure time to water and repeated freezing-thawing environment. It shows clearly observed microstructure investigations.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.107-113
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• 2010

In this study, the relative effects of low-chloride deicier(LCD) and two other deicing agents on the scaling of concrete were conducted in a series of tests at laboratory accordance with the ASTM C 672. The solutions concentration of deicers tested included 1, 4, 10%. Tap water was used as control. The amount of scaling was evaluated gravimetrically. As test result of deicer solution types, when applied to 4% solutions, surface scaling of concrete after 56 freeze-thaw cycles was produced significantly as about 9 times on LCD solution, as about 18 times on $CaCl_2$ solution, and as about 33 times on NaCl solution comparing with tap water. As test result of deicer solution concentrations, relatively low concentrations (of the 4% by weight) of deicer were produced more surface scaling than higher concentrations (of the 10% by weight) or lower concentrations (of the 1% by weight) of deicer. It show that the damaging concentration is of the order of 3~4% for previous research result. It appears that the mechanism of surface scaling is primarily physical rather than chemical. Also, the effect of chloride deicier types, freeze-thaw cycling, and air contents on the performance of concrete was experimentally investigated. The results show that the concrete specimens subjected to freeze-thaw cycling scaled more severely in exposure to deicing salt than those in non-exposure to deicing salt, weight losses of the specimens tested in exposure to deicing salt were twice as much as those tested in non-exposure to deicing salt. Relative dynamic modulus of elasticity of concrete specimens decreased more quickly in exposure to deicing salt than in non-exposure to deicing salt. Also, relative dynamic modulus of elasticity of concrete specimens in exposure to sodium chloride deicing salt was decreased more quickly comparing with exposure to LCD salt. It is also shown that the chloride contents according to concrete specimen depths was more largely in exposure to LCD salt. When concrete specimen is exposed to chloride deicing salts and freeze-thaw cycling, performance degradation in the entrained air concrete(AE concrete) retarded more considerably comparing with non-entrained air concrete(Non-AE concrete).

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.161-164
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• 2008

In recent years, carbon fiber-reinforced polymer (CFRP) has been widely used for repairing and/or strengthening structural elements in concrete. Not enough test data, however, are available to predict the long-term performance of the repaired and improved structures exposed to weathering. The objective of this research is to study the effect of freeze-thaw cycling on the behavior of reinforced concrete (RC) beams strengthened in shear with carbon fiber sheet. Six small-scale RC beams (100mm${\times]$100mm${\times]$400mm) were strengthened with CFRP in shear, subjected to up to 400 cycles freeze-thawing from -17${\sim}4^{\circ}C$, and tested to failure in four-point bending. Test result, there was no significant damage to carbon fiber sheet strengthened concrete beams had been suffered 30 cycles of freeze-thawing, and more over 60 cycles of freezing-thawing brought about a reduction in resistance of only 25% of the initial level.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.593-596
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• 2008

Domestic area of most be happened chloride deicer damage. Because daily mean temperature is below 0$^{\circ}C$ from the area of domestic most. Use of deicing chemicals has been and will continue to be a major part of concrete structure in the highway. Chloride-containing chemicals such as calcium chloride or rock salt are main deicers for the road. Extensive use of chloride deicers is, however, not only the source of substantial cost penalties due to their corrosive action and ability to deterioration roadway surface materials but also the source of environmental damages. Chloride-containing chemicals such as calcium chloride or rock salt are main deicers for the road. Extensive use of chloride deicers is, however, not only the source of substantial cost penalties due to their corrosive action and ability to deterioration roadway surface materials but also the source of environmental damages. In this study, Use of deicing chemicals has been and will continue to be a major part of highway freeze-thaw durability and carbonation of concrete surface protecting materials