• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.537-540
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• 2006

Over the past few decades, a considerable number of studies on the durability of concrete have been carried out extensively. A lot of improvements have been achieved especially in modeling of ionic flows. However, the majority of these researches have not dealt with the chloride binding isotherm based on the mechanism, although chloride binding capacity can significantly impact on the total service life of concrete under marine environment. The purpose of this study is to develop the model of chloride binding isotherm based on the individual mechanism. It is well known that chlorides ions in concrete can be present; free chlorides dissolved in the pore solution, chemical bound chlorides reacted with the hydration compounds of cement, and physical bound attracted to the surface of C-S-H grains. First, sub-model for water soluble chloride content is suggested as a function of pore solution and degree of saturation. Second, chemical model is suggested separately to estimate the response of binding capacity due to C-S-H and Friedel's salt. Finally, physical bound chloride content is estimated to consider a surface area of C-S-H nano-grains and the distance limited by the Van der Waals force. The new model of chloride binding isotherm suggested in this study is based on their intrinsic binding mechanisms and hydration reaction of concrete. Accordingly, it is possible to characterize chloride binding isotherm at the arbitrary stage of hydration time and arbitrary location from the surface of concrete. Comparative study with experimental data of published literature is accomplished to validity this model.

• 분석과학
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• 제25권1호
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• pp.33-38
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• 2012

염화물 고정화능력의 중요성에도 불구하고 고정화능력을 측정하는 것은 어려우며 특히, 이미 건설되어 공용중인 구조물에서는 더욱 어렵다. 실제로 고정염화물을 측정하는 과정은 온도, 시료의 분말도, 공극수 추출기법 등과 같은 환경적 요인에 의해 큰 영향을 받는다. 본 연구에서는 X-선 회절분석법(XRD; X-ray diffraction)을 이용하여 콘크리트 내 염화물 이온의 고정화능력을 정량화하는 방법에 대해 중점을 두고 연구를 진행하였다. 염화물의 고정능력 isotherm은 물/시멘트비, 양생기간, 결합재 종류에 영향을 받으며 Langmuir isotherm 을 통하여 일단 결정된 고정염화물(Friedel 염)은 XRD를 이용하여 동시에 분석을 진행한다. XRD 그래프에서 나타난 고정염화물량의 피크 강도와 측정된 고정염화물의 총량의 관계를 결정한다. 결과적으로 양생기간이 증가될수록, 물/시멘트비가 감소될수록 고정화 능력은 증가하였다.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.464-466
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• 2010

• 한국구조물진단유지관리공학회 논문집
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• 제12권5호
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• pp.133-142
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• 2008

본 연구에서는 보통포틀랜드시멘트(OPC: ordinary Portland cement), 플라이애쉬(PFA: pulverised fly ash), 고로슬래그미분말(GGBFS: ground granulated blast furnace slag), 실리카퓸(SF: Silica fume)등의 각종 결합재를 적용한 시멘트 페이스트의 염소이온 고정화능력에 관하여 연구하였다. 각각의 사용 시멘트 페이스트는 40%의 물/결합재로 PFA, GGBFS 및 SF 혼화제의 각기 다른 치환률을 갖도록 하였으며 미리 혼합수내에 결합재 중량당 0.1~0.3%의 염소이온을 배합수내에 혼입 포함시켜 배합되어 제조되었다. 염소이온의 측정은 7일간 양생 후 수분 추출 방법을 이용하여 측정하였다. 실험을 통해 염소이온 고정화 능력이 결합재 종류 및 치환률에 의존하고 있음을 확인하였고, 총 염소이온량의 증가는 염소이온 고정화능력을 제한하여 결론적으로 염소이온 고정화를 감소시키고 있음을 보였다. 본 연구에서 최대 30%의 치환율을 가진 PFA와 60%의 치환률을 가진 GGBFS의 경우는 OPC보다 염소이온고정화 능력이 작았으며, SF의 치환률의 증가는 고정화를 감소시키고 있음을 확인하였으며, 이는 포졸란계 재료의 잠재 수화반응 혹은 공극수의 pH 저하등의 이유로 판단된다. 재령 7일에서의 염소이온의 고정화능력은 염해부식에 대한 저항성으로 나타내어지며, 염분을 혼입한 경우의 고정화능력의 순서는 30%PFA > 10%SF > 60%GGBFS > OPC로 나타났다. 더욱이 염소이온의 고정화 거동은 Langmuir isotherm 및 Freundlich isotherm으로 잘 표현될 수 있음을 보였다.

• Computers and Concrete
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• 제13권6호
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• pp.695-707
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• 2014

This study investigated the chloride binding isotherms of various cement types, especially the contributions of C-S-H and AFm hydrates to the chloride binding isotherms were determined. Ordinary Portland cement (OPC), Modified cement (MC), Rapid-hardening Portland cement (RHC) and Low-heat Portland cement (LHC) were used. The total chloride contents and free chloride contents were analyzed by ASTM. The contents of C-S-H, AFm hydrates and Friedel's salt were determined by X-ray diffraction Rietveld (XRD Rietveld) analysis. The results showed that OPC had the highest chloride binding capacity, and, LHC had the lowest binding capacity of chloride ions. MC and RHC had very similar capacities to bind chloride ions. Experimental equations which distinguish the chemically bound chloride and physically bound chloride were formulated to determine amounts of the bound chloride basing on chloride binding capacity of hydrates.

• 콘크리트학회논문집
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• 제29권4호
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• pp.389-397
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• 2017

시멘트내 $C_3A$상과 $C_4AF$상은 염소이온과 반응하여 프리델염을 생성한다. 프리델염은 구조체에서 염소를 포함하기 때문에 염소이온의 흡착에 매우 중요하다. 외부에서 염소이온이 침투하면, 칼슘 알루미네이트 수화물은 염소이온을 고정하므로, $C_3A$상과 $C_4AF$상 및 AFm상의 염소 흡착 거동을 고찰하는 것은 고정화 현상을 이해하는데 매우 중요하다. 한편, 흡착 등온은 시멘트와 프리델염의 상호관계에서 정량적인 지식을 제공할 뿐만 아니라 그 상호관계의 특성을 이해하는데 매우 중요하다. 본 연구의 목적은 $C_3A$상, $C_4AF$상 및 AFm상의 염소이온 흡착 거동을 고찰하는데 있다. $C_3A$상과 $C_4AF$상의 흡착등온은 이론적 화학당량보다 다소 낮았으며 Langmuir 흡착등온식으로 표현할 수 있었다. AFm상의 흡착등온은 이론적 화학당량보다 매우 낮았으며, Freundlich 흡착등온식으로 표현하였다. 또한 흡착등온 모델에서 온도의 영향 매개변수를 실험범주내에서 온도의 함수로 제안하였다.

• 한국의류학회지
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• 제27권5호
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• pp.523-523
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• 2003

The change of interactions of anionic surfactants, sodium dodecyl sulfate(SDS) and sodium tetradecyl sulfate(575) in the presence of electrolytes, to the chitosan-based polyelectrolyte(sol＇n and gel phase) were studied. The chitosan gel used in this study were crosslinked with epichlorohydrin(ECH). Binding isotherms were determined by potentiometric technique using a surfactant ion selective solid-state electrode and the results were represented by using the sequence generating function(SGF) method. The results of binding isotherm were shown comparatively high cooperativity. The addition of electrolytes in the chitosan/SDS system resulted in a shift of the binding to higher free surfactant concentration because of screen effect by the electrolytes. Degree of binding of chitosan gel was higher than that of chitosan sol＇n. And also a conformational phase transition of the chitosan gel in the presence of electrolytes has been investigated.

• 한국의류학회지
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• 제27권5호
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• pp.524-532
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• 2003

The change of interactions of anionic surfactants, sodium dodecyl sulfate(SDS) and sodium tetradecyl sulfate(575) in the presence of electrolytes, to the chitosan-based polyelectrolyte(sol＇n and gel phase) were studied. The chitosan gel used in this study were crosslinked with epichlorohydrin(ECH). Binding isotherms were determined by potentiometric technique using a surfactant ion selective solid-state electrode and the results were represented by using the sequence generating function(SGF) method. The results of binding isotherm were shown comparatively high cooperativity. The addition of electrolytes in the chitosan/SDS system resulted in a shift of the binding to higher free surfactant concentration because of screen effect by the electrolytes. Degree of binding of chitosan gel was higher than that of chitosan sol＇n. And also a conformational phase transition of the chitosan gel in the presence of electrolytes has been investigated.

• 한국염색가공학회지
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• 제24권4호
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• pp.239-246
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• 2012

The binding isotherms of ionic dyes with Poly(vinylpyrrolidone) in aqueous solution were determined by the dynamic dialysis technique. The shape of the isotherms of cationic dye, C. I. Basic Red 18 with poly(vinlypyrrolidone) showed a partition type. It suggests that the binding involves a non-cooperative mode. Isotherms of an anion dye, a synthesized dye by coupling of diazotized m-trifluoromethylaniline with 2-naphthol-6-sulfonic acid, were sigmoid type and showed multimode interaction. The results were interpreted by the McGhee von Hippel theory. The thermodynamic parameters for the complex formation of the dyes-polymer were calculated from their temperature dependences of the intrinsic binding constant.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권6호
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• pp.431-435
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• 2000

The goal of this research is to compare the metal binding characteristics of an anoxic selector activated sludge system and a conventional activated sludge system. Metal biosorption by biomass harvested from experimental systems was determined by a series of batch experiments. Heavy metals studied in this research were zinc, cadmium, and nickel. The sorption isotherm showed that the selector sludge had significantly higher sorption capacity than did the control sludge. Metal biosorption behavior closely followed a Freundlich isotherm model for equilibrium concentrations. ECP contents of biomass estimated by alkali extraction technique showed that ECP levels in the selector sludge significantly higher than that in the sludge harvested from the conventional system, indicating that the higher metal sorption capacity of selector sludge may be due to the selection of the ECP-producing bacteria (i.e., Zoogloea sp.) by the selector system.