• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.315-316
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• 2023

In the present investigation, the chloride ion penetration resistance of nuclear power plant concrete with varying water-to-cement ratios was assessed. A comparative analysis was conducted on concretes that do not incorporate supplementary cementitious materials, such as fly ash, using permanently decommissioned nuclear structures as a reference. The objective is to employ this acquired data as a fundamental resource for the evaluation of the residual service life of nuclear power plant structures in subsequent studies.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.727-730
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• 2005

The purpose of this study evaluates possibilities of waste phosphogypsum into concerts by steam curing admixture. The waste phosphogypsum is made use of 4 forms(Dehydrate, $\beta$-Hemihydrate, III-Anhydrite and II-Anhydrite) which were changed to in low temperature of calcination. The penetration depth and compressive strength of cement mortar are investigated to evaluate the chloride ion and carbonation resistance. As a result, chloride ion and carbonation resistance of cement mortar admixed with waste phosphogypsum are more excellent than cement mortar contained OPC alone. The internal pores of cement mortar are decreased by using waste phosphogypsum, because the hydrates of ettringite which is denesified in structure is much formed in early ages at steam curing. These densified effect is concluded with improving the resistance to attack of cement mortar including waste phospogypsum.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.329-331
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• 2013

The salt damage resistance of waterproofing membrane was evaluated on the cracked mortar substrate. The types of specimens are urethane, acrylic waterproofing membrane, and no coating mortar substrate. After these specimens were cured by water curing for 4 weeks, they were cured by atmospheric curing at 20±2Co for 8 weeks. The salt water immersion test was carried out by following KS F 2737, and the penetration depth of chloride ion into substrate was measured in 1, 4, 8, and 13 weeks. As a result, in the case of non coating specimen, the chloride ion penetrated within one week. In the coated specimens, a regardless of the membrane type, the chloride ion did not penetrate during 13 weeks-tests on condition that the cracked width of substrate is less than 0.3mm. Also, the penetration speeds of the coated specimens were lower than that of non coating specimen. Therefore, our results reached a conclusion that waterproofing membrane has high salt damage resistance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.161-166
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• 1998

The main object of this study is to examine the basic properties of fresh concrete as well as hardened concrete using several types of cement such as ordinary portland cement, sulphate resisting portland cement, blast furnace slag cement, ternary blended cement. In addition, effects of each cement on the durability including drying shrinkage, freeze-thawing resistance, resistance of chloride ion penetration, carbonation of concrete were investigated. As the results of this study, it was proved that most of the properties of concrete using each cement were similar, but there were some differences in bleeding, setting time, resistance of chloride ion penetration and carbonation.

• 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.

• 한국구조물진단유지관리공학회 논문집
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• 제14권3호
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• pp.138-143
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• 2010

최근 들어 대형 해양콘크리트 구조물의 건설이 빈번해짐에 따라 콘크리트의 염화물이온확산계수를 정확히 평가할 필요성이 대두되고 있으나, 콘크리트의 염화물이온 확산계수 평가는 장시간이 소요되는 단점 때문에 전기화학적인 전위차 촉진에 의해 단시간에 염화물이온의 확산계수를 추정하기 위한 여러 촉진 시험방법들이 제안되고 있으나 이에 대한 체계적인 연구가 아직은 미비한 실정이다. 따라서 본 연구에서는 시멘트의 성분이 다른 3종류의 시멘트를 대상으로 대표적인 3가지 전기적인 촉진시험에 의해 콘크리트중의 염화물이온의 침투 및 확산특성을 평가하고 이 방법간의 상관성을 분석하였다. 평가결과 시멘트의 성분에 따라 염화물이온의 확산특성은 크게 달라졌으며, 그 중 고로 슬래그 미분말과 플라이애시를 일정비율로 혼합한 3성분계 시멘트의 확산특성이 가장 우수하였으며, 염화물이온 확산 특성은 결과로부터 시험방법간의 상관성은 양호한 것으로 나타났다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2004년도 학술대회지
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• pp.71-76
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• 2004

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 $3\sim4$ replacement ratios under W/B ratios ranged from 0.40 to 0.55. Specimens were immersed in $3.6\%$ NaCl solution for 330 days, and penetration depth, water soluble chloride contents and acid soluble chloride contents were measured in 28, 91, 182 and 330 days. Then, diffusion coefficient were calculated using total chloride contents. As a results. the kinds of mineral admixture and replacement ratios had a great effect on the resistance property of the concrete to chloride ion invasion compared with the plain concrete. And the optimal replacement ratios of mineral admixture had a limitation for each admixtures. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures and the penetration depth from the concrete skin. Chloride diffusion coefficient of each concretes decreased with the time elapsed. and the diffusion coefficients of the concrete immersed salt water for 330 days had a establishment with the compressive strength measured before immersing.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.253-254
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• 2022

In this study, catechol-functionalized chitosan (Cat-Chit), a well-known bioinspired polymer that imitates the basic structures and functions of living organisms and biological materials in nature, was synthesized and combined with cement mortar in various proportions. The compressive strength, tensile strength, drying shrinkage, accelerated carbonation depth, and chloride-ion penetrability of these mixes were then evaluated. In the ultraviolet-visible spectra, a maximum absorption peak appeared at 280 nm, corresponding to catechol conjugation. The sample containing 7.5% Cat-Chit polymer in water (CPW) exhibited the highest compressive strength, and its 28-day compressive strength was ~20.2% higher than that of a control sample with no added polymer. The tensile strength of the samples containing 5% or more CPW was ~2.3-11.5% higher than that of the control sample. Additionally, all the Cat-Chit polymer mixtures exhibited lower carbonation depths than compared to the control sample. The total charge passing through the samples decreased as the amount of CPW increased. Thus, incorporating this polymer effectively improved the mechanical properties, carbonation resistance, and chloride-ion penetration resistance of cement mortar.

• 한국건설순환자원학회논문집
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• 제2권1호
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• pp.34-39
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• 2014

이 연구의 목적은 하이볼륨 플라이애시(HVFA) 콘크리트의 강도수준 및 플라이애시의 혼입률별로 콘크리트 내의 철근부식 및 염소이온 침투 저항성을 평가하는 것이다. 이를 위하여 물-결합재비 및 플라이애시 혼입률에 따라 철근 상부를 노출시킨 원주형 공시체와 통상적인 원주형 공시체를 제작하였으며, 이들 각각에 대해 압축강도 및 염소이온 침투 저항성 시험과 전기화학적 방법에 의한 철근부식 촉진시험을 수행하였다. 실험 결과, 대체적으로 플라이애시 혼입률이 많을수록 HVFA 콘크리트의 압축강도는 감소하였으나, 철근부식 및 염소이온 침투 저항성은 크게 개선되는 것으로 나타났다.