• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.63-69
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• 2015

It has been well known that concrete structures exposed to chloride and sulfate attack environments lead to significant deterioration in their durability due to chloride ion and sulfate ion attack. The purpose of this experimental research is to evaluate the resistance against chloride ion and sulfate attack of the cementless concrete replacing the cement with ground granulated blast furnace slag. For this purpose, the cementless concrete specimens were made for water-binder ratios of 40%, 45%, and 50%, respectively and then this specimens were cured in the water of $20{\pm}3^{\circ}C$ and immersed in fresh water, 10% sodium sulfate solution for 28 and 91 days, respectively. To evaluate the resistance to chloride ion and sulfate attack for the cementless concrete specimens, the diffusion coefficient for chloride ion and compressive strength ratio, mass change ratio, and length change ratio were measured according to the NT BUILD 492 and JSTM C 7401, respectively. It was observed from the test results that the resistance against chloride ion and sulfate attack of the cemetntless concrete were comparatively largely increased than those of OPC concrete with decreasing water-binder ratio.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.25-26
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• 2018

In this study, the device was developed for evaluating the effect of pressure on chloride ion penetration of concrete. And chloride-ion penetration depth and water soluble chloride contents was evaluated concrete using ordinary portland cement and blast-furnace slag cement using developed device. As a result, chloride ion penetration of concrete was promoted according to the action of pressure and the exposure period. and the incorporation of blast-furnace slag was effective for chloride attack resistibility under pressure.

• Journal of the Korean Society of Safety
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• v.22 no.3 s.81
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• pp.57-64
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• 2007

Recently, the corrosion of concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the influences of carbonation and freezing-thawing action to chloride attack in concrete structures. The test results indicate that the chloride penetration is more pronounced than the case of single chloride attack when the carbonation process is combined with the chloride attack. It is supposed that the chloride ion concentration of carbonation region is higher than the sound region because of the separation of fixed salts. Though the use of fly ash pronounces the chloride ion concentration in surface, amounts of chloride ion penetration into deep region decreases with the use of fly ash. The small reduction of relative dynamic elastic modulus induced from freezing-thawing increases the chloride ion penetration depths much. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of both chlorides and carbonation or freezing-thawing but the future studies for combined environment will assure the precise assessment.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1045-1050
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• 2001

This study was performed to evaluate reinforced concrete durability in chloride attack environment under sustained load by the corrosion of reinforcing bars and the permeation of chloride ion. Generally, it is regarded that permeability of chloride ion is determined by the properties of concrete, but the effects of load which make alternation of concrete inner structure such as crack and so on should not neglected. In this study, it is shown that the relation between bending load on RC beam, deflection and crack of specimen, permeation of chloride ion, rating of re-bar corrosion, and the relation between compression load and permeation of chloride ion. Therefore the effects of load on permeation of chloride ion and re-bar corrosion are evaluated.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.149-156
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• 2016

It has been well known that concrete structures exposed to chloride and sulfate attack environments lead to significant deterioration in their durability due to chloride ion and sulfate ion attack. The purpose of this experimental research is to evaluate the long-term durability against chloride ion and sulfate attack of the alkali activated cementless concrete replacing the cement with ground granulated blast furnace slag. For this purpose, the cementless concrete specimens were made for water-binder ratios of 40%, 45%, and 50%, respectively and then this specimens were cured in the water of $20{\pm}3^{\circ}C$ and immersed in fresh water, 10% sodium sulfate solution for 28, 91, 182, and 365 days, respectively. To evaluate the long-term durability to chloride ion and sulfate attack for the cementless concrete specimens, the diffusion coefficient for chloride ion and compressive strength ratio, mass change ratio, and length change ratio were measured according to the NT BUILD 492 and JSTM C 7401, respectively. It was observed from the test results that the resistance against chloride ion and sulfate attack of the cemetntless concrete were comparatively largely increased than those of OPC concrete irrespective of water-binder ratio.

• 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 Korea Concrete Institute Conference
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• 2000.10a
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• pp.461-466
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• 2000

To improve the quality of concrete, we usually consider the reduction of water/cement ratio, the increase of concrete cover depth and the use of mineral admixtures. Reportedly, the use of admixtures make concrete more durable and tighten against water. But, it is needed to study more about the relationship between the admixtures and the chloride ion diffusion. Therefore, in this study, we focused on the chloride ion diffusion properties of the pozzolanic admixtures such as fly-ash, slag and silica fume which are known as being useful on chloride attack resistance when mixed into mortar or concrete. Furthermore, we treed to analyze the correlation between mortar and concrete using the admixture, which is useful for analyzing chloride ion diffusion mechanism.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.213-214
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• 2010

An objective of this experimental research is to investigate the diffusion characteristics for chloride ion of concrete subjected to sulfate attack. For this purpose, concretes with three types of cement such as ordinary portland cement(OPC), binary blended cement(BBC), and ternary blended cement(TBC) containing mineral admixtures were made for water-binder ratios of 32% and 43%. The concrete specimens were immersed in sulfate solution for 365 days, and then the resistance against chloride ion penetration of them were estimated by using NT BUILD 492. It was observed from the test results that the resistance to chloride ion penetration of concrete subjected to sulfate attack was greatly decreased than that of standard curing concrete under the same age.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.223-230
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• 2006

In this paper the method for repair LCC evaluation of reinforced concrete structures deteriorated by chloride attack was constructed. Also, the FEM analysis for chloride ion penetration into concrete was conducted to evaluate the repair LCC which was decided by the number of repair times including early stages of construction and repair construction during the service life of structures. As a result, the number of repair times is obtained from the comparing the concentration of the chloride ion in a rebar position, and the critical chloride ion concentration of rebar corrosion through the FEM analysis considering the kind of repair materials and methods. Also, the repair LCC could be calculated by the number of repair times during the service life of structures.

• Geomechanics and Engineering
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• v.10 no.6
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• pp.807-826
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• 2016

In this study, aiming to investigate the effects of sulfate attack on cement stabilized highly plastic clay; an experimental study was carried out considering the effects of cement type, sulfate type and its concentration, cement content and curing period. Unconfined compressive strength and chloride-ion penetration tests were performed to obtain strength and permeability characteristics of specimens cured under different conditions. Test results were evaluated along with microstructural investigations including SEM and EDS analyses. Results revealed that use of sulfate resistance cement instead of normal portland cement is more plausible for soils under the threat of sulfate attack. Besides, it was verified that sulfate concentration is responsible for strength loss and permeability increase in cement stabilized montmorillonite. Finally, empirical equations were proposed to estimate the unconfined compressive strength of cement stabilized montmorillonite, which was exposed to sulfate attack for 28 days.