• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문 발표회
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• pp.43-48
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• 2003

This paper investigate that the effect of the concrete containing mineral admixtures(pozzolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for 3~4 replacement ratios under W/B ratios ranged from 0.40 to 0.55. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a results, the W/B ratios, kinds of admixture and replacement ratios, water curing periods had a great effect on the migration coefficient of chloride ion, and the optimal replacement ratios of admixture had a limitation for each admixtures. Also, the addition of mineral admixtures by mass(replacement of OPC) enhanced the resistance of the mixture to chloride penetration compared with the plain concrete. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures. The compressive strength was shown related to the migration coefficient of chloride ion, the compressive strength increased with the decreasing migration coefficient of chloride ion. Below the 50MPa, the variation of migration coefficient of concrete added mineral admixtures was bigger than plain concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.43-48
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• 2003

This paper investigate that the effect of the concrete containing mineral admixtures(pozzaolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for 3∼4 replacement ratios under W/B ratios ranged from 0.40 to 0.55. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a results, the W/B ratios, kinds of admixture and replacement ratios, water curing periods had a great effect on the migration coefficient of chloride ion, and the optimal replacement ratios of admixture had a limitation for each admixtures. Also, the addition of mineral admixtures by mass(replacement of OPC) enhanced the resistance of the mixture to chloride penetration compared with the plain concrete. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures. The compressive strength was shown related to the migration coefficient of chloride ion, the compressive strength increased with the decreasing migration coefficient of chloride ion. Below the 50MPa, the variation of migration coefficient of concrete added mineral admixtures was bigger than plain concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.711-714
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• 2003

Factors causing deterioration of concrete structures under marine environment are various, especially penetration and diffusion of chloride ion, carbon dioxide, and water through pore effects on the durability of concrete as well as mechanical properties of concrete. Pore of porous materials like concrete can be classified as micro-, meso-, and macro-pore. And pore of cement matrix is classified as pore which occupied by water, air void, and ITZ between cement paste and aggregates. In this study, to verify the relationship between pore of cement matrix and the property of chloride ion diffusivity, the regression analysis is producted. From the result of regression analysis, the average pore diameter more than total pore volume effects on the diffusivity of chloride ion.

• 한국건설순환자원학회논문집
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• 제11권4호
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• pp.381-390
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• 2023

본 연구에서는 염해를 받은 콘크리트의 역학적 성능 평가를 수행하고, 실험 결과를 바탕으로 염소이온 농도에 따른 압축응력변형률 모델을 제시하였다. 염해를 모사하기 위해 콘크리트 배합 시 CaCl₂ 용액을 첨가하였으며, 염소이온의 농도는 결합재의 중량 대비 0, 1, 2, 4 %가 되도록 하였다. 콘크리트의 최대 압축응력 이후의 응력-변형률 곡선을 조사하기 위해 변위 제어를 통해 압축강도를 측정하였다. 염소이온 농도가 1 %인 경우에는 최대 압축응력이 증가하였으나, 염소이온 농도가 2 % 이상인 경우에는 최대 압축응력이 감소하였다. 최대 압축응력에서의 변형률의 경우 재령 7일의 시편에서는 염소이온 농도에 따른 경향이 나타나지 않았다. 재령 28일의 시편에서는 염소이온 농도가 증가함에 따라 감소하였다. 재령 28일의 최대 압축응력와 변형률의 변화를 이용하여 Popovics model에 기반한 응력-변형률 곡선 모델을 제시하였다. 염소이온의 농도 증가에 따른 역학적 성능 저하의 원인을 조사하기 위해 수화생성물 분석을 수행하였다. 염소이온의 농도가 증가함에 따라 Friedel's salt가 증가하고, portlandite가 감소하는 것을 확인하였다.

• 한국농공학회논문집
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• 제57권5호
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• pp.43-49
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• 2015

Most of agricultural structures located in seashore could not avoid rapid deterioration of concrete because chloride-ion and $CO_2$ gradually penetrate into concrete. However, since most of models can be able to describe the phenomenon of penetration by using one or two dimensional models based on finite difference method (FDM), those modes can not simulate the real geometry and it takes a lot of computational time to complete even the calculation. To overcome those weaknesses, three dimensional numerical model considering time dependent variables such as surface concentration of chloride and diffusion coefficient of domain based on finite element method (FEM) was suggested. This model also included the neutralization occurred by the penetration of $CO_2$. Because the model used various sizes of tetrahedral mesh instead of equivalent rectangular mesh, it reduced the computational time to compare with FDM. As this model is based on FEM, it will be easily extended to execute multi-physics simulation including water evaporation and temperature change of concrete.

• 한국건축시공학회지
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• 제17권4호
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• pp.341-348
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• 2017

콘크리트 포장도로는 동절기 제설제에 의한 내구성 저하가 심각한 위협으로 거론되고 있고 그 보수에도 많은 비용이 소요되고 있다. 따라서 이러한 콘크리트 포장재에 대한 적절한 보수 대책의 마련과 이에 활용될 우수한 성능의 보수 재료가 요구되고 있는 상황인데, 본 연구에서는 국내에서 개발된 인산마그네슘 세라믹(Magnesium phosphate ceramics)을 대상으로 압축강도 특성 및 염소이온 침투 저항성, 길이변화 특성을 평가하여 국내 콘크리트 포장 도로의 보수 재료로 적용 가능성을 검토하였다. 평가 결과 모르타르의 유동성은 190mm의 평범한 수준을 나타내었으나 다소 점성이 높고 재료 자체의 흐름성은 크지 않았다. 응결 시간은 12분으로 매우 빠른 경화가 이루어졌으며 이에 따라 신속한 작업이 요구되었다. 모르타르의 압축강도 성능은 2시간에 38.4MPa, 24시간에 73.8MPa, 28일에 111.0MPa로 재령 초기부터 높은 수준을 나타내었다. 염소이온 침투 저항성 시험 결과 모르타르의 경우 143 Coulombs, 콘크리트의 경우 173 Coulombs으로 매우 우수한 수준을 나타내었다. 콘크리트의 길이변화 시험 결과는 재령 40일까지 $60{\times}10^{-6}$ 이하로 완만하게 감소하였으며, 보통의 시멘트 콘크리트의 길이변화 수준과 비교할 때 1/10 이하의 수준으로 우수한 체적안정성을 확보하고 있었다. 이상과 같이 인산마그네슘 세라믹은 우수한 강도 성능과 염소이온 침투 저항성, 체적 안정성을 보유하고 있음을 확인하였고, 향후 작업 시간이나 작업성에 대한 개선이 요구되며, 현장 적용시에는 이러한 부분에 대한 주의가 필요하다.

• 한국건축시공학회지
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• 제18권6호
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• pp.507-515
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• 2018

본 연구의 목표는 숏크리트 타설시의 분진 발생 문제, 낮은 알칼리도의 유지를 통한 환경부하 감소 및 시멘트 광물계가 가지는 빠른 초기강도 발현의 특성을 동시에 가지는 슬러리형 급결제를 개발하고, 이를 활용하여 고성능 내염해성 숏크리트의 현장 타설에 적용하는 것이다. 본 연구에서는 물결합재비 0.44 및 0.338의 두 종류의 숏크리트 배합에 대하여 슬러리형 급결제를 현장 적용시켰으며, 현장에서 얻은 숏크리트 및 숏크리트용 베이스 콘크리트 시험체의 강도 및 내염해성을 비교 분석하였다. 실험 결과에 따르면, 슬러리형 급결제는 두 종류의 숏크리트 배합에 모두 성공적으로 적용 되었으며, 이를 이용하면 1일 강도 10MPa 28일 강도 40MPa급의 고성능 숏크리트의 제조가 가능한 것을 확인하였다. 물결합재 0.338의 숏크리트 배합에서, 고로슬래그 미분말의 활용시 1일강도는 물결합재비 0.44의 숏크리트 배합보다 다소 낮게 나타났으나, 28일 재령에서의 강도가 현저히 역전되었으며, 염해저항성이 크게 개선되는 것을 확인하여, 고로슬래그 미분말이 고성능 내염해성 숏크리트의 개발에 성공적으로 활용될 수 있음을 확인하였다.

• Computers and Concrete
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• 제19권5호
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• pp.489-499
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• 2017

Self-Compacting Concrete (SCC) is a new technology capable to flow without segregation or any addition of energy which leads to efficient construction and cost savings. In this study, the effect of replacing the Ordinary Portland Cement (OPC) with Fly Ash (FA) on the strength, durability of the concrete was investigated experimentally, and carbon footprint and cost were also assessed. Four different replacement FA ratios (0%, 20%, 40% and 60%) were used to create four SCC mixes. Standard test methods were used to determine the workability, strength, and durability of the SCC mixes including resist chloride ion penetration, water permeability, water absorption, and initial surface absorption. The axial cube compressive strength tests were performed on the SCC mixes at 1, 7, 14, 28 and 35 days. Replacing the OPC with FA had a significant positive impact on chloride iron penetration resistance and water absorption but had a considerable negative impact on the compressive strength. The SCC mix with 60% FA had 36.7% and 15.8% enhancement in the resistance to chloride ion penetration and water absorption, respectively. Evaluation of the carbon footprint and the cost of each SCC mixes showed the $CO_2$ emissions mixes 1, 2, 3 and 4 were significantly reduced by increasing the FA content from 0% to 60%. Compared with the control mix, the cost of all mixes increased when the FA content increased, but no significant differences were seen between the estimated costs of all four mixes.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.269-272
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• 2006

Chloride ion diffusion is the most important thing of occuring deterioration in RC structure. So it is important to decide the precise chloride ion diffusion coefficient in order to predict the durability life in RC structure. The purpose of this study is to analyze the established data, which are restricted by chloride diffusion coefficient, and to calculate chloride ion diffusion coefficient using RCPT test. To examine the prediction of the concrete structure durability by an FEM analysis and the chloride diffusion coefficient as a variable. Each surface finishing materials were effective on the increment of chloride penetration resistance, but showed a little different effect depending on the type of surface finishing material.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.411-414
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• 1999

In this study, the characteristics of concrete strength according to age/curing condition and the penetration mechanism of seawater into the concrete has been studied. To this end, a comprehensive experimental program has been setup. The major test variables include the type of cement and the type of mineral admixture. The strength test as well as corrosion test have been conducted to explore the effects of chloride ion penetration on the properties of concrete. The experimental results and the developed theory in the present study can be efficiently used to analyze the chloride ion penetration and to estimate the durability of concrete structures.