Journal of the Korea Institute of Building Construction (한국건축시공학회지)

The Korean Institute of Building Construction (한국건축시공학회)
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The Chloride Ion Diffusivity of Ready-Mixed Concrete Depending on Specified Compressive Strength

레디믹스트 콘크리트의 설계기준 압축강도별 염소이온 확산특성

  • Park, Dong-Cheon (Department of Architecture and Ocean Space, Korea Maritime and Ocean University) ;
  • Kim, Yong-Ro (Technology Research & Development Institute)
  • Received : 2018.08.30
  • Accepted : 2018.10.15
  • Published : 2018.12.20
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Abstract

The RC buildings which are constructed on the seaside are followed by KBC(2016) to achieve the minimization of durability damage. To control the corrosion of the reinforcing steel bar by salt attack, W/C should be under 0.4 and specified concrete strength is higher than 35MPa in the concrete/building construction standard specification. Even though it has been proved that the concrete mixed with mineral admixture such as blast furnace slag and fly ash etc. have high strength and durability in previous researches, the beneficial informations are not applied to the codes. Ready-mixed concretes which usually include the admixtures in Busan were tested to certify the salt attack durability. In the same specified concrete strength, remarkable salt attack durability was evaluated in comparison to OPC. For economical and reliable durability design, chloride ion diffusivity should be measured before applying to new building construction.

해안도시에 건설하는 건축물의 콘크리트 배합은 환경조건에 따라 설계기준 압축강도로 제한하고 있으나 혼화재 혼입에 의해 염해 내구성이 급격히 향상되고 있음이 기존연구에서 명확히 되고 있으나 아직 규정에 반영되고 있지는 못한 실정이다. 본 연구에서는 레미콘의 배합을 분석하고 비교 시험체 제작을 통하여 염해 내구성에 대한 건축구조기준을 만족시키면서 경제성을 가지는 결과를 도출하고자 하였다. 시판되는 레미콘의 경우 설계기준 압축강도 이상의 강도와 그에 따른 염소이온 차단성을 가지며 전 배합조건에 대해서 OPC 35MPa를 능가하는 성능을 확인할 수 있었다. 내구성 및 경제성을 동시에 달성하기 위해서 납품 전 사전배합을 실시하여 염해 저항성을 포함한 기본물성을 검토할 필요가 있다고 사료된다.

Keywords

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Figure 1. Slump value by specific concrete strength

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Figure 2. Air content by specific concrete strength

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Figure 3. Compressive strength(28d) and specific concrete strength

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Figure 4. Increase of compressive strength from 28d to 91d

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Figure 5. Chloride ion diffusion coefficient by specific concrete strength (28d, 91d)

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Figure 7. Changes of chloride ion diffusion coefficient from 28d to 91d

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Figure 8. Relationship between chloride ion diffusion coefficient and W/B

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Figure 9. Relationship between chloride ion diffusion coefficient and specified concrete strength

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Figure 10. Chloride ion condensation at concrete depth 50mm

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Figure 6. Penetration depth of chloride ion (91d)

Table 1. The replacement ratio of BFS

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Table 2. Concrete mixture and experiment

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Table 3. Apparent chloride ion diffusion coefficient used in durability design

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