• 한국구조물진단유지관리공학회 논문집
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• 제16권6호
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• pp.73-81
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• 2012

콘크리트 구조물은 일반적으로 동결융해 작용을 받는 조건에 노출되고, 이러한 동결융해작용은 콘크리트의 공극구조를 변화시키고, 콘크리트의 내구성을 저하시킬 우려가 있다. 따라서 본 연구에서는 동결융해작용에 의한 콘크리트 내부공극구조 변화와 동결융해작용을 받은 콘크리트의 내구특성을 평가하고자 하였다. 실험결과, 기존의 동결융해 평가기법에 따르면 모든 배합에서 우수한 내구성능을 나타내었으나, 동결융해 작용에 노출됨에 따라 50~100nm 크기의 공극이 크게 증가하며, 콘크리트 염화물침투저항성이 저하하였다. 수중양생 콘크리트의 공극구조와 염화물 침투저항성은 선형관계를 보이지만, 동결융해작용을 받으면 내부공극구조의 변화로 선형관계가 저하하였다. 동결융해작용과 염화물침투를 동시에 받는 구조물의 내구성 평가기준에 대한 재검토가 필요할 것으로 판단된다.

• 한국재난정보학회 논문집
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• 제9권4호
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• pp.493-502
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• 2013

이 연구의 목적은 낙동강에 대규모로 부존되어 있는 세사를 콘크리트 잔골재로서 적극적으로 활용하기 위하여 이를 사용한 콘크리트의 건조수축 및 내구성을 평가하는 것이다. 이를 위하여 낙동강 본류의 중 하류에서 하천세사를 채취한 후 강도수준에 따라 콘크리트 배합실험을 수행하였다. 그 결과로부터 압축강도와 시멘트-물비의 상관식을 도출한 후 하천세사 종류별로 설계기준강도 35MPa에 대해서 콘크리트 공시체를 제작하여 이들의 건조수축과 동결융해 및 탄산화 저항성과 같은 내구성을 평가하였다. 그 결과, 하천세사를 사용한 콘크리트의 내구성은 기준모래를 사용한 콘크리트의 경우와 유사한 것으로 나타났으나, 하천세사의 건조수축은 조립률이 작은 경우 기준모래를 사용한 콘크리트보다 비교적 큰 것으로 나타났다.

• International Journal of Concrete Structures and Materials
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• 제11권1호
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• pp.85-97
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• 2017

Research has suggested that conventional lightweight concrete can offer durability advantages due to reduced cracking tendency. Although a number of publications exist providing the results of laboratory-based studies on the durability performance of lightweight concrete (with lightweight coarse aggregate) and internally cured concrete (using prewetted lightweight fine aggregate), far fewer field studies of durability performance of conventional lightweight concrete bridge decks in service have been performed. This study was commissioned to provide insight to a highway agency on whether enhanced durability performance, and therefore reduced maintenance and longer lifecycles, could be anticipated from existing lightweight concrete bridge decks that were not intentionally internally cured. To facilitate performance comparison, each lightweight bridge deck selected for inclusion in this study was paired with a companion normalweight bridge deck on a bridge of similar structural type, deck thickness, and geometric configuration, with similar age, traffic, and environmental exposure. The field-observed cracking of the decks was recorded and evaluated, and crack densities for transverse, longitudinal, and pattern cracking of the normalweight and lightweight deck in each pair were compared. Although some trends linking crack prevalence to geographic location, traffic, and age were observed, a distinct difference between the cracking present in the paired lightweight and normalweight bridge decks included in this study was not readily evident. Statistical analysis using analysis of covariance (ANCOVA) to adjust for age and traffic influence did not indicate that the type of concrete deck (lightweight or normalweight) is a statistically significant factor in the observed cracking. Therefore, for these service environments, lightweight decks did not consistently demonstrate reduced cracking.

• 한국도로학회논문집
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• 제18권1호
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• pp.63-72
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• 2016

PURPOSES : The use of roller-compacted concrete pavement (RCCP) is an environmentally friendly method of construction that utilizes the aggregate interlock effect by means of a hydration reaction and roller compacting, demonstrating a superb structural performance with a relatively small unit water content and unit cement content. However, even if an excellent structural performance was secured through a previous study, the verification research on the environmental load and long-term durability was conducted under unsatisfactory conditions. In order to secure longterm durability, the construction of an appropriate internal air-void structure is required. In this study, a method of improving the long-term durability of RCCP will be suggested by analyzing the internal air-void structure and relevant durability of roller-compacted concrete. METHODS : The method of improving the long-term durability involves measurements of the air content, air voids, and air-spacing factor in RCCP that experiences a change in terms of the kind of air-entraining agent and chemical admixture proportions. This test should be conducted on the basis of test criteria such as ASTM C 457, 672, and KS F 2456. RESULTS : Freezing, thawing, and scaling resistance tests of roller compacted concrete without a chemical admixture showed that it was weak. However, as a result of conducting air entraining (AE) with an AE agent, a large amount of air was distributed with a range of 2~3%, and an air void spacing factor ranging from 200 to $300{\mu}m$ (close to $250{\mu}m$) coming from PCA was secured. Accordingly, the freezing and thawing resistance was improved, with a relative dynamic elastic modulus of more than 80%, and the scaling resistance was improved under the appropriate AE agent content rate. CONCLUSIONS : The long-term durability of RCCP has a direct relationship with the air-void spacing factor, and it can be secured only by ensuring the air void spacing factor through air entraining with the inclusion of an AE agent.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.661-666
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• 2002

The safety and serviceability of concrete structures are influenced by corrosion of steel bars in concrete. Several methods have been available to protect the reinforcing bars from corrosion. Among them, the surface coating method is one of the easiest way to apply to concrete structures. However, the realistic guideline for surface coating materials has not been established yet in this country. In this study, in order to establish a reasonable technical guidelines, the durability of the concrete treated by coatings was evaluated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.739-744
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• 2001

In this study, experimental research was carried out to develop protective finishing, coating materials and new hybrid technique for deteriorating prevention and high durability in concrete structures. It had sufficiently recommended performance for the protective finishing method of concrete structures through testings. This is more progressive double membrane method than single membrane type designed by conventional method. It was found that this hybrid construction method had very excellent performance to improve the durability of existing concrete structures and attain the beauty of concrete structures.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.455-460
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• 2000

Fly ash can be used as cement replacement material and can also produce the durable concrete. According to the results, the compressive strength of concrete containing fly ash is slightly lower than that of normal concrete at early ages, however, the long-term compressive strength is significantly higher beyond 90 days, and it increases the durability of concrete as well.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.675-680
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• 2003

In this study, various tests are performed for the durability of the concrete using domestic recycled coarse aggregate including drying shrinkage, permeability, freezing-thawing resistance and $CO_2$ diffusivity. Tests of freezing-thawing resistance, chloride ion permeability and $CO_2$ diffusivity of recycled concrete show favorable results. But, the maximum drying shrinkage ratio to normal concrete is increased 24% with increasing substitution ratio of recycled aggregate. Therefore, for the use of recycled concrete in structures, the preventive measures of drying shrinkage is necessary in mix design and the adequate substitution ratio of recycled aggregate should be proposed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.207-212
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• 1996

Recently, massive concrete structures exposed to salt from ocean marine environments, or from winter deicing. The corrosion caused by chloride-penetration may affect severey the durability and service life of such a concretestructures. Thus, it is necessary to develop durable concrete to enhance the corrosion resistance. In this study, we investigate the usage of adequate corrosion-protection materials in order to reduce permability-coefficient of concrete and method of enhancing the durability of concrete structures using by penetrating corrosion-protection materials.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.117-118
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• 2022

High-strength concrete is used for building durability on the coast. It is common to order and produce the concrete from several ready mixed concrete companies. The concrete in Busan was also commissioned by 12 ready mixed concrete companies. The compressive strength and salt diffusion coefficient were measured. The average value and deviation were analyzed.