• Magazine of the Korea Concrete Institute
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• v.27 no.5
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• pp.30-35
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• 2015

• Magazine of the Korea Concrete Institute
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• v.4 no.4
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• pp.115-122
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• 1992

폐쇄 폐콘크리트를 재활용한 재생콘크리트의 강도특성을 천연골재를 사용한 일반콘크리트와 비교하였다. 동결융해 처리수의 압축강도와 3점휨 재하시험하의 변형율을 측정하였다. 재생콘크리트는 동결융해 처리 후 압축강도 보존율이 더 높았다. 재생콘크리트는 또한 높은 변형율과 처짐에 민감함을 보였으나 파괴와 관련된 다른 성질들은 일반콘크리트와 유사하거나 더 좋은 것으로 나타났다. 그러므로 폐콘크리트를 구조용 콘크리트 제조에 재 사용이 가능할 것으로 보여진다. 그러나 실제 사용을 위하여는 콘크리트에 있어서 중요한 성질인 압축강도가 더 증진되어야 하며 최대 변형율도 보다 자세히 점검되어야 한다.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.11-17
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• 2013

This study was performed to evaluate the chlorine ion penetration resistance, chemical resistance and freezing and thawing resistance used ordinary portland cement, crushed coarse aggregate, crushed sand, river sand, fly ash, limestone powder, blast furance slag powder and superplasticizer to find optimum mix design of low carbon green concrete for structures. The performance of low carbon green concrete used fly ash, limestone powder and blast furnace slag powder were remarkably improved. This fact is expected to have economical effects in the manufacture of low carbon green concrete for offshore structures. Accordingly, the fly ash, limestone powder and blast furnace slag powder can be used for offshore structure materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.739-742
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• 2005

In this study, we predicted the service life against the freezing and thawing. as a result, we found that in the case of using the low quality crushed sand with high water-cement ratio, there is the possibility of deterioration. but in any other case, we concluded that there is no chance to deteriorate if we have the required air contents by using AE agent. we are going to improve the method to evaluate more exactly the durability of the concrete with crushed sand by acquiring data from the specimen which are exposed to field for long time.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.31-39
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• 2013

In this study, performance of the post-installed anchor system was evaluated with reduced strength of concrete and anchor. One of the post-installed anchors was selected to performance evaluation. Concrete strength was reduced by freeze-thawing test, and the post-installed anchor strength was reduced by corrosion test. The post-installed Anchor was installed in concrete of freezing and thawing and original concrete, and corroded anchor was installed in original concrete only. Anchor diameter and installation depth of the anchor were the variable for each specimen. Performance of post-installed anchor system of each specimen was evaluated by pullout test. Anchor diameter and installation depth of anchor, it may affect the performance of the post-installed anchor system from the experimental test results. Fracture mode of each post-installed anchor system had occurred differently depending on the durability of concrete and anchor. The anchor pullout strength from the experimental test results was used in order to compare with the results of CCD (Concrete Capacity Design) method, and CCD equation was modified. Modified equation was able to predict the anchor pullout strength of post-installed anchor system in Original concrete and freezing and thawing of concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.43-46
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• 2009

The purpose of this study is to enhance durability of concrete structures that uses this surface protecting material by carrying out the performance test of the surface protecting material of concrete, and as s result, we reached out the conclusion as follow. 1. As a result of the test measuring the stability and adhesive power of conductive film against ultraviolet, freezing & thawing, and damage from seawater that deteriorate the surface protecting material, it was turned out to meet the performance criteria specifying in the KS standard enough to gain a good evaluation to use as a surface protecting material. 2. As a result of the test identifying the neutralization-furtherance, it was assessed to be capable of protecting effectively concrete structures from carbonic acid gas by a very low depth of 0.1mm of neutralization. 3. As a result of the test identifying Penetrated Resistance Properties of chloride ion, as it was turned out to have a very low value of 819 Coulombs, it was assessed that even in the environment where the corrosion by chloride such sea environment is very affective, the film can effectively protect the concrete structure. 4. As a result of the test identifying freezing & thawing, as there was no change in reduction of mass after 400 cycle, it was assessed that the film has a good resistance against freezing & thawing. According to the results of study above, it is expected that this technology can extend its durability of concrete structure and be widely used for concrete structure through means (methods) to prevent the neutralization and damage from seawater as original purposes of the surface protecting material.

• Magazine of the Korea Concrete Institute
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• v.4 no.3
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• pp.157-166
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• 1992

해수환경하의 콘크리트 구조물은 동결융해의 반복에 의한 물리적인 침식과 해수중에 용존하는 각종의 이온들의 침투로 인한 화학적 침식에 의해 현저한 성능저하현상을 나타내는 것으로 알려져있다. 본 연구는 포졸란계 혼합재인 플라이 애쉬, 슬래그, 슬리카 흄과 폴리머계 혼합재인 Ethylene Vinyl Acetate(EVA), Styrene-Butadiene Rubber(SBR)를 사용하여 제조한 콘크리트 경화체의 해수환 경하에서 동결융해 저항성에 미치는 혼합재의 종류 및 첨가량의 영향, W/C의 영향을 비교 검토한 실험적 연구이다. 콘크리트의 동결융해 저항성을 위해서는 공기연행이 필수적이며, 공기연행시킨 경우 W/C가 낮을수록 동결융해 저항성이 우수하였다. 해수중에서의 동결융해 저항성은 슬래그분말을 첨가할 때 우수하였으며, 폴리머계 혼합재에서는 EVA가 우수한 결과를 나타내었다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.270-278
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• 2005

Recycled aggregate concrete has lower strength and durability compared to concrete with natural aggregate. Therefore, metakaolin is used to improve the properties of recycled aggregate concrete. Main components of metakaolin are $SiO_2$ and $Al_2O_3$. and specific surface area is 9 times larger than that of ordinary portland cement. Quality of demolished-recycled aggregate(DRA) satisfies the type 1 of KS F 2573, but quality of source-recycled aggregate(SRA) does not satisfy with the type 2 of KS F 2573. When metakaolin was replaced with 20% of cement, compressive strength of concrete with SRA and DRA develops about 40~64% of control concrete. Water absorption ratio was reduced about 2% by replacing 20% metakaolin and it represents low compared to the natural aggregate concrete without metakaolin. In addition, the resistance to freezing and thawing, of concrete with DRA is indicated to remarkably enhanced due to the contribution of metakaolin. However, when metakaolin is replaced with 20% of cement, relative dynamic modulus of elasticity of concrete with SRA was below 60% at 210 freezing and thawing cycles.

• International Journal of Highway Engineering
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• v.20 no.3
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• pp.11-18
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• 2018

PURPOSES : Durability of concrete is traditionally based on evaluating the effect of a single deterioration mechanism such as freezing & thawing action, chloride attack, carbonation and chemical attack. In reality, however, concrete structures are subjected to varying environmental exposure conditions which often results in multi-deterioration mechanism occurring. This study presents the experimental results on the durability of concrete incorporating air-cooled slag(AS) and/or water-cooled slag(WS) exposed to multi-deterioration environments of chloride attack and freezing & thawing action. METHODS : In order to evaluate durable performance of concretes exposed to single- and multi-deterioration, relative dynamic modulus of elasticity, mass ratio and compressive strength measurements were performed. RESULTS :It was observed that multi-deterioration severely affected durability of concrete compared with single deterioration irrespective of concrete types. Additionally, the replacement of cement by AS and WS showed a beneficial effect on enhancement of concrete durability. CONCLUSIONS : It is concluded that resistance to single- and/or multi-deterioration of concrete is highly dependent on the types of binder used in the concrete. Showing the a good resistance to multi-deterioration with concrete incorporating AS, it is also concluded that the AS possibly is an option for concrete materials, especially under severe environments.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.79-87
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• 2011

Concrete incorporating high volume blast-furnace slag placed in cold weather regions might be in danger of initial frost damage because dependently on the mix proportions, the setting and the hardening would be remarkably delayed. Therefore, this study investigated to effect of the degree of frost on the strength development and the resistance to freezing and thawing of the concrete incorporating blast-furnace slag when being subjected to freeze at early age. As the experimental results, the concrete incorporating blast-furnace slag attacked by initial frost damage showed the remarkable reduction of both the compressive strength development and the resistance to freezing and thawing. Especially, the resistance to freezing-thawing of the concrete incorporating high volume blast-furnace slag became much lower than that of the normal concrete.