• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.757-763
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• 2011

In order to secure the effective high early age strength of the concrete, the study was carried out with a goal of functional improvement of cement. This study was carried out as a follow up for the previous study, which analyzed the high early age strength and durability of concrete mixed with fine particle cement (FC) during cement production. The experimental results showed that the target range for each mix was satisfied at fresh state of concrete. Also, when mixed with fine particles cement, the setting time improved. Additionally, compressive strength and heat of hydration increased and remained same, respectively. Especially, the durability remained same even when mixed with fine particle cement.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.320-328
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• 2007

The durability of marine concrete structures is severely degraded by corrosion due to seawater attack and diffusion of chloride in concrete. The deduction of durability causes high repair cost for maintenance of marine concrete structure. So, the applicability of high-durable materials is investigated to improve the durability in marine concrete structures. For these, the characteristics of corrosion prevention of marine concrete structures mixed with the mineral admixtures(SF, FA and BFS), the modified steel(stainless and coating steel), and corrosion inhibitors are evaluated using electro-chemical methods. As a results of this study, it is quantified for the effect of promotion of durability by high-durability materials in marine concrete structures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.343-352
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• 2010

Recently, many researchers have been carried out to estimate more controlled service life and long-term performance of carbonated concrete structures. Durability analysis and design based on probability have been induced to new concrete structures for design. This paper provides a carbonation prediction model based on the Fick's 1st law of diffusion using statistic data of carbonated concrete structures and the probabilistic analysis of the durability performance has been carried out by using a Bayes' theorem. The influence of concerned design parameters such as $CO_2$ diffusion coefficient, atmospheric $CO_2$ concentration, absorption quantity of $CO_2$ and the degree of hydration was investigated. Using a monitoring data, this model which was based on probabilistic approach was predicted a carbonation depth and a remaining service life at a variety of environmental concrete structures. Form the result, the application method using a realistic carbonation prediction model can be to estimate erosion-open-time, controlled durability and to determine a making decision for suitable repair and maintenance of carbonated concrete structures.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.773-784
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• 2008

Even if the exploitation of copper slag produced during the smelting process of copper as aggregate for construction purpose has been permitted since 2004 in Korea, the lack of sufficient data enabling to evaluate its long-term stability that is its durability has to date impeded its application. This study intends to investigate experimentally the durability characteristics of 18 and 27 MPa-class commercial concretes in which natural sand (fine aggregates) has been partially replaced by copper slag through accelerated and exposure tests so as to provide bases promoting the application of copper slag concrete. The experimental results revealed insignificant difference of the durability characteristics in most of the mix proportions in which 30% of natural sand was replaced by copper slag. In the case where crushed sand was adopted, tests verified similar characteristics for replacement ratio of 50%. Particularly, the results of the exposure test conducted during 8 years demonstrated that equivalent level of durability was secured compared to the case using natural sand. In the case of 18MPa-class lower grade concrete, exposure test verified also that the physical lifetime similar to 50 years could be secured until carbonation reaches cover depth of 20 mm.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.239-246
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• 2004

To improve the durability of concrete structure, we usually consider the reduction of water-cement ratio, the increase of concrete cover depth and the use of mineral admixtures. The use of admixtures make concrete more durable and tighten against water in recent papers so it is needed to study more about the relationship between the admixtures and the chloride ion diffusion. Therefore we analyzed the correlation between chloride ion diffusion and physical properties such as compressive strength, void ratio, air permeability of the concrete, and tried to use them as fundamental data for analyzing chloride ion diffusion mechanism of the concrete mixed with mineral admixtures.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.545-548
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• 2008

As the corrosion of reinforcing bar in concrete structures exposed to chloride attack is one of main factors to determine the remaining service life, marine concrete structures have to be designed to protect the chloride penetration. Among the durability design methods such as deterministic method and probabilistic method, design method based on the probabilistic theory has been widely studied. However, the most essential material, data of the material properties related to chloride diffusion, are still insufficient. In this paper, the probabilistic distribution of chloride diffusion coefficients and aging coefficients are derived by the experiment and analysis for the chloride coefficients of concrete containing pozzolans, which are generally used in marine structures.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.125-132
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• 2006

Recently, surface finishing and protection materials were developed to restore performance of the deteriorated concrete and inhibiting corrosion of the reinforcing-bar. For this purpose, surface protection agent as well as coatings are used. Coatings have the advantage of low Permeability of $CO_2,\;SO_2$ and water. However, for coatings such as epoxy, urethane and acryl, long-term adhesive strength is reduced and the formed membrane of those is blistered by various causes. Also when organic coatings are applied to the wet surface of concrete, those have a problem with adhesion. On the other hand, surface protection agent penetrates into pore structure in concrete through capillary and cm make a dense micro structure in concrete as a result of filling effect. Furthermore, the chemical reaction between silicate from surface protection agent and cement hydrates can also make a additional hydration product which is ideally compatible with concrete body. The aim of this study is to examine the effect of penetrative surface protection agent(SPA) by evaluating several concrete durability characteristics. The results show that the concrete penetrated surface protection agent exhibited higher durability characteristics for instance, carbonation velocity coefficient, resistance to chemical attack and chloride ion penetration than the plain concrete. These results due to formation of a discontinuous macro-pore system which inhibits deterioration factors of concrete by changed the pore structure(porosity and pore size distributions) of the concrete penetrated surface protection agent.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.157-157
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• 2011

프리캐스트 콘크리트 박스 암거는 현장 타설식 암거에 비해 구조물의 고품질화 및 반복적인 대량생산으로 원가 절감과 건식화 시공으로 인한 공정의 단순화와 공기가 단축되는 이점을 지니고 있다. 따라서 본 연구는 상재 허용하중을 확보하고, 시공성 및 내구성이 뛰어나며, 경제성을 고려한 고성능 프리캐스트 박스 암거를 개발하고 향후 고성능 프리캐스트 박스 암거를 생산하기 위한 기초적인 자료를 제시하고자 하였다. 본 연구에서는 기존의 보통 포틀랜드 시멘트를 이용한 프리캐스트 박스 암거의 경제성 및 내구성, 강도특성을 개선하고자 고로슬래그를 이용하여 최적의 배합비를 산출하고, 이를 토대로 중성화, 염해, 동결융해 등의 시험을 통해 내구성을 확보하고, 휨 성능을 확인하고자 실물박스암거를 제작하여 외압강도시험을 실시하였다. 또한 구조해석을 통해 응력검토를 하였다. 내구성 검토 결과, 분말도 $6,000cm^2/g$을 가진 고로슬래그 미분말을 50%로 혼입한 콘크리트가 보통 포틀랜드 시멘트를 사용한 콘크리트보다 염화물이온 투과성에 대한 저항성 및 동결융해 저항성 등 기초물성 및 내구성이 개선됨을 알 수 있었다. 박스암거에 대한 휨 시험 결과, OPC에 비해 GFSC6의 경우는 크게 구조적 성능이 떨어지지는 않는 것으로 나타났으며, 균열양상 및 연성도에서는 우수함을 나타냈다. ABAQUS에 의한 비선형 해석 결과는 시험체의 휨 거동을 잘 묘사하는 것으로 나타났으며, 처짐의 경우 시험체의 시험결과보다 크게 나타났지만, 처짐 양상은 비슷한 것을 알 수 있었고, 벽체와 상부 슬래브에 발생하는 응력은 부재가 허용하는 균열응력값 이내로 나타남에 따라 사용하중 상태에서의 응력검토는 안전한 것으로 판단된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.5
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• pp.47-54
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• 2018

Concrete undergoes various deterioration on surface. Impregnant with silicate is usually applied to concrete surface and forms insoluble hydrates, which can provide many engineering advantages. In the work, concrete impregnated with colloidal silicate is used for durability enhancement in surface and self-clearing performance is evaluated with photocatalyst-$TiO_2$ spraying. For the work, various tests are performed both for strength evaluation and durability evaluation such as absorption ratio, drying shrinkage, chloride penetration, sulfate resistance, and freezing/ thawing action. Furthermore, removal and self-clearing performance are evaluated with Acetaldehyde decomposition and Methylene blue decolorization. Through silicate impregnation and photocatalyst spraying, the impregnated concrete can have not only durability enhance but also self-clearing performance.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.304-304
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• 2011

최근 도시화에 따른 인구증가와 더불어 도로포장 등 불투수면적의 증가로 인하여 우기시 빗물 침투가 차단되어 도심의 지하수위가 저하되며 토양의 건토화, 열섬현상 등의 문제가 발생하게 되었다. 이러한 문제점에 착안하여 본 연구에서는 투수효과를 최대한 고려할 수 있는 고강도의 친환경 콘크리트 블록(에크스톤 바이오 블록; ECOSTONE-BIO BLOCK)을 개발하였으며 기존 콘크리트 블록의 자연적 빗물침투 억제의 문제점을 일부 개선하였다. 본 블록은 캡슐공법을 사용하여, 공극률은 높이면서(투수성 향상), 강도와 내구성이 유지됨은 물론 캡슐안에 황토성분을 첨가하여, 바이오적인 기능 및 재생골재를 이용한 친환경적 제품으로 투수성, 내구성, 기능성을 극대화 시켰다. 또한 제품표면은 천연 백색돌맹이, 흑색돌맹이의 배합으로 자연석재 느낌을 구현하였으며, 쇼트블라스트 및 커링 표면공정으로 미끄럼저항지수를 조절할 수 있어, 기존 콘크리트 보도블록에 비해 투수율, 내구성, 기능성, 안전성이 우수하여, 안전한 보행환경이 가능한 것으로 분석되었다. 마지막으로, 주변 환경과 잘 어울리도록 디자인된 바이오기능성 친환경 블록으로 도심지역 시공시 투수효과에 따른 지하수고갈방지 및 침수피해에 도움을 주리라 사료된다.