• Title/Summary/Keyword: Friedel's salt

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Chloride binding isotherms of various cements basing on binding capacity of hydrates

  • Tran, Van Mien;Nawa, Toyoharu;Stitmannaithum, Boonchai
    • Computers and Concrete
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    • v.13 no.6
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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.

Mechanical Properties of Ternary Blended Cement Containing PAC (PAC을 포함한 삼성분계 시멘트의 역학적 특성)

  • Kim, Taewan;Cheung, Jin-Hwan;Kim, Seong-Do;Kim, In-Tae
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.2
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    • pp.245-253
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    • 2020
  • The present study is an experimental study to investigate the characteristics of strength by mixing polyaluminum chloride(PAC) with OPC-slag-FA ternary blended cement. There are three types of binders: 80% OPC + 10% slag + 10% FA, 60% OPC + 20% slag + 20% FA, and 40% OPC + 30% slag + 30% FA. PACs used 0, 2, 4, 6, 8, and 10% of the mixing-water weight. Experimental results show that PAC improves compressive strength regardless of the amount of OPC. PAC consumes portlandite, forms Friedel's salt, and reduces the diameter of the pores, making the matrix compact, contributing to the improvement of compressive strength. However, porous FA particles had an effect of delaying hydration by absorbing PAC in the initial hydration step. Therefore, the use of FA needs to determine the substitution rate in consideration of the hydration delay effect.

Development of Eco-friendly Cement using Reverse Osmosis Brine Water and Metakaolin (역삼투압 농축수와 메타카올린을 사용한 친환경 시멘트의 개발)

  • Kim, Taewan;Han, Ki-Bong;Kim, Do-Hyung;Seo, Ki-Young
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.2
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    • pp.216-222
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    • 2021
  • This is an experiment to complement new ways of using concentrated water discharged from the seawater desalination plant. In this study, metakaolin, which has excellent chloride ion immobilization effect, was used as the main binder, and 10% and 20% of calcium oxide were substituted with the activator. In addition, tap-water(TW) and reverse osmosis brine water(RW) were used as mixed water. As a result of the experiment, the mixture using RW showed higher compressive strength than TW. It also showed low water absorption and high density. In the mixture using RW as mixed water, a hydration reaction substance called Friedel's salt could be observed. Considering the corrosion problem of steel, RW is considered to be applicable to products such as non-reinforced concrete, brick, and curb stone. Through this study, it is thought that it is meaningful to propose a new application method other than the ocean release of RW.

A study of semi-quantification of the Friedel's salt using the X-ray diffraction method in concrete (콘크리트 내 Friedel염의 XRD를 이용한 반정량적 측정기법에 관한 연구)

  • Lee, Ho-Jae;Lee, Jang-Hwa;Kim, Do-Gyeum
    • Analytical Science and Technology
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    • v.25 no.1
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    • pp.33-38
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    • 2012
  • Despite the importance of chloride binding, it is very difficult to measure the binding capacity, in particular, for the concrete body in an existing structure: in fact, the measurement procedure for chloride binding is much influenced by the environmental condition such as temperature, fineness of sample and pore water extraction techniques. The present study concerns the quantification of the binding capacity of chloride ions in concrete using the X-ray diffraction (XRD) technique. Once the binding isotherm of chlorides was determined by the Langmuir isotherm, as a function of the W/C, curing age and binder type, the generation of bound chlorides (i.e. Friedel's salt) was simultaneously ensured by the XRD technique. The amount of bound chloride was then determined by analyzing the peak intensity for the bound chlorides in the XRD curve. It was found that an increase in the curing age and a decrease in the W/C resulted in an increase in the binding capacity.

Experiment on Chloride Adsorption by Calcium Aluminate Phases in Cement (시멘트내 칼슘 알루미네이트 상에 의한 염소이온의 흡착반응 연구)

  • Yoon, In-Seok
    • Journal of the Korea Concrete Institute
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    • v.29 no.4
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    • pp.389-397
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    • 2017
  • Friedel's salt is an important product of chemical adsorption between cement hydrate and chloride ions because it contains chlorine in its structure. When cement reacts with water in the presence of chloride ions, the $C_3A$ phase, and $C_4AF$ phase react with chloride to produce Friedel's salt. If chloride ions penetrate into concrete from external environments, many calcium aluminate hydrates, including AFm, can bind chloride ions. It is very important, therefore, to investigate the chloride binding isotherm of $C_3A$ phase, $C_4AF$ phase, and AFm phase to gain a better understanding of chloride binding in cementitious materials. Meanwhile, the adsorption isotherm can provide us with the fundamental information for the understanding of adsorption process. The experimental results of the isotherm can supply not only the quantitative knowledge of the cement-Friedel's salt system, but also the mechanism of adsorption and the properties of their interactions. The purpose of this study is to explore the time dependant behaviors of chloride ions adsorption with $C_3A$, $C_4AF$ and AFm phases. The chloride adsorption isotherm was depicted with Langmuir isotherm and the adsorption capacity was low in terms of the stoichiometric point of view. However, the chloride adsorption of AFm phase was depicted with Freundlich isotherm and the value was very low. Since the amount of the adsorption was governed by temperature, the affecting parameters of isotherm were expressed as a function of temperature.

The Effect of Seawater on the Hydration of Clinker Minerals (II) Acceleration Experiment in the Artificial Seawater (시멘트 클린커광물의 수화에 미치는 해수성분의 영향 (II) 인공해수에서의 촉진시험)

  • 신도철;송태웅;최상흘;한기성
    • Journal of the Korean Ceramic Society
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    • v.25 no.1
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    • pp.15-20
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    • 1988
  • In this study, the specimens of cement clinker minerals such as 80C3-S-15C4AF-5C3A added various blending materials were immersed in artificial seawater. In order to ascertain the effect of SO3 and blending materials on seawater resistance of the specimens, the acceleration experiment in the artificial seawater was carried out by repeating of immersion and drying operation periodically. As inner part of the specimen immersed in artificial seawater, Friedel's salt was produced by reaction with Cl ion. In outer part of the specimen, gypsum and ettringite were mainly formed. With the increase of SO3 content in the specimen the formation of ettringite was increased and Frieldel's salt in inner part was decreased. Total pore volume of the specimens was increased according to the amount of Cl ion penetrated and Mg(OH)2 leached in the solution.

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Seawater Attack Resistance of Mortars Containing Mineral Admixtures (광물질혼화재 혼합 모르타르의 해수침식 저항성)

  • 문한영;이승태;최강식
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.527-530
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    • 2002
  • In the present study, immersion test using artificial seawater was performed to evaluate the resistance of mortar specimens with or without ground granulated blast-furnace slag (SG) and fly ash (FA). Another variable was the fineness levels of SG (4,450, 6,000 and 8,000 ㎠/g). From the results of the immersion test for 270 days of exposure, the excellent resistance to seawater attack for SG mortar mixtures, especially in a high fineness levels, was confirmed. However, the reductions in compressive strength of FA mortar specimens was similar to those of OPC mortar specimens irrespective of replacement of FA.. In order to understand the deterioration mechanism due to seawater attack, X-ray diffraction (XRD) analysis were also carried out. Some reactants such as ettringite, gypsum, brucite and Friedel's salt were possibly detected through XRD technique.

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Microstructure modification and electrochemical properties of steel corrosion in the blended cement systems containing internal chlorides (고농도 염화물을 함유하는 혼합시멘트 계에서 철근부식에 따른 미세구조의 변화와 전기화학적 특성)

  • 나종윤;이승헌;김창은
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.131-134
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    • 1999
  • Microstructure modification and electrochemical properties are investigate to estimate the effects of internal chlorides on the steel corrosion in the blended cement systems. According to the test results, slag cement system showed high chloride binding capacity and low corrosion rate. The impedance data showed three distince arcs from lowest(mHz) frequency to highest (MHz) frequency due to product layer, interfacial reaction and bulk matrix. Through the microstructural investigation, fine steel-matrix interface of slag cement system was observed but rough steel-matrix interface of OPC system was observed. Friedel's salt was thought that the substantial material contributed to the chloride binding of slag cement system.

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Removal of Cl from the Incineration Ash of Domestic Municipal Solid Waste

  • Han, Gi-Chun;Kim, Hyung-Seok;Ahn, Ji-Whan;Kim, Hwan
    • Proceedings of the IEEK Conference
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    • 2001.10a
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    • pp.628-632
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    • 2001
  • The removal rate of Cl from municipal solid waste incineration(MSWI) ash(bottom ash and fly ash) by washing was investigated. The Cl contents in the bottom ash and fly ash were 2.6-3.0% and 25-30% respectively, and KCl, NaCl, CaCIOH and friedel's salt were main components. From the results on the effects of washing time and temperature, the Cl contents in the bottom ash and fly ash were decreased up to 0.3% and 2.0% respectively by using of water as a solvent within 30 min at 2$0^{\circ}C$, 300 rpm of agitation speed and 10 of liquid/solid ratio. It is expected that the removal of Cl from the incineration ash by washing could make use of the ash for a cement raw material and so on.

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