• Title/Summary/Keyword: cement composition

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The impact of altered chemical composition on cement hydration reactivity (변화된 화학조성이 시멘트 수화반응성에 미치는 영향)

  • Choi, Ji-Ung;Son, Joeng-Jin;Kim, Ji-Hyun;Chung, Chul-Woo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.11a
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    • pp.191-192
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    • 2023
  • This study, evaluated the effect of changes in the chemical composition of cement on the hydration reaction for carbon neutrality. For this purpose, changes in the chemical bound water and heat of hydration between current cement and past cement were compared. As a result, it was found that both the chemically bound water and heat of hydration of currently used cement decreased.

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A Effect of Chemical Composition and Replacement Ratio of Limestone Admixture on Initial Cement Characteristics (석회석 혼합재의 화학성분과 치환량이 시멘트 초기 물성에 미치는 영향)

  • Dong-Kyun Suh;Gyu-Yong Kim;Jae-Won Choi;Kyung-Suk Kim;Ji-Wan Woo
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.11 no.4
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    • pp.440-448
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    • 2023
  • Utilizing admixture, which is one of the raw material replacement method in the cement industry, is expected to be easily and quickly put to practical use as it is relatively more accessible than other methods. Among cement admixtures, limestone powder is reported to be able to improve cement performance through nucleation effects, chemical effects, and filler effects, so it is a material expected to be suitable as a cement admixture. Meanwhile, as high-quality limestone is depleted around the world, the use of limestone with clay or high magnesia (MgO) content is becoming increasingly inevitable. Therefore, in this study, we attempted to evaluate the suitability of limestone cement as a admixture by measuring the basic properties of limestone cement mixed with limestone of different qualities commonly used in Korea. As a result, the effect of alite reaction promotion was confirmed regardless of the chemical composition of the limestone binder. However, the dilution effect depending on the substitution amount was greater than the chemical composition. It is believed that normal-grade limestone can be used as a mixture as long as the limestone content in cement is within 15 % in this scope of study. In the future, we plan to evaluate the impact of the chemical composition of the limestone mixture through additional experiments depending on the chemical composition of cement.

A Study of Effecting Factor in the Reology and Physical Properties of Cements (시멘트 유동성과 물성에 미치는 영향인자에 관한 연구)

  • 엄태선;최상흘
    • Journal of the Korean Ceramic Society
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    • v.34 no.10
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    • pp.1027-1036
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    • 1997
  • The reology and several physical properties of cements are studied by varying the different mineral composition and particle size distribution(PSD) of cements with closed circuit ball mill for high workability, low heat of hydration, and high strength. In this study, we found that the workability of concretes is related to the viscosity of cement, and affects to strength. Here, this workability is affected by mineral composition (C3A) and the PSD. Especially, rosin-rammer index and 44${\mu}{\textrm}{m}$ residue in the PSD of cements are affected to water demand, casting property, slump loss, strength of cements. From the above results, the conditions of cement for high workability, low heat of hydration and high strength are to use low C3A clinker, 5-10% slag addition, and to grind cement below 0.7 rosin-rammer index, above 3.5-4.5% 44 ${\mu}{\textrm}{m}$ residue, 4000$\pm$100 $\textrm{cm}^2$/g blaine. Such cements are, therefore, supurior to super low heat cement and slag-blended cement in comparing the physical properties of strength, slump, slump-flow, adiabetic temperature, etc.

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Properties of Recycled Cement by Content of Fine Aggregate from Waste Concrete Powder (폐콘크리트 미분말의 골재함유량에 따른 재생시멘트의 물성)

  • Bae, Jong-Kun;Kwon, Eun-Hee;Ahn, Jae-Cheol;Park, Dong-Cheon;Kang, Byeung-Hee
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2012.05a
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    • pp.101-102
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    • 2012
  • A policy for recycling waste concrete has been extensively studied, but it is still lacking to recycle and reuse as a cementitious powder, and the property has big different depending on the aggregate rates. In this study, the amount of cement powder according to the internal properties of the aggregate were mixed. From as a result, Concrete Powder to play inside the aggregate composition of the cement composition CaO rigs that causes loss of power and strength reduction due to rising real water cement ratio will affect large.

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CO2 Emissions Reduction by Utilization of Recycled Cement (재생시멘트 활용에 따른 CO2배출량 저감효과)

  • Kwon, Eun-Hee;Ahn, Jae-Cheol;Hwang, Jong-Wook;Park, Dong-Cheon
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2013.11a
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    • pp.78-79
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    • 2013
  • A policy for recycling waste concrete has been extensively studied, but it is still lacking to recycle and reuse as a cementitious powder, and the property has big different depending on the aggregate rates. In this study, the amount of cement powder according to the internal properties of the aggregate were mixed. From as a result, Concrete Powder to play inside the aggregate composition of the cement composition CaO rigs that causes loss of power and strength reduction due to rising real water cement ratio will affect large.

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The Study on Portland Cement Stabilization on the Weathered Granite Soils (on the Durability) (화강암질 풍화토의 시멘트에 의한 안정처리에 관한 연구 (내구성을 중심으로))

  • 도덕현
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.22 no.3
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    • pp.60-74
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    • 1980
  • Soil-cement mixtures involve problems in it's durability in grain size distribution and mineral composition of the used soils as well as in cement content, compaction energy, molding water content, and curing. As an attempt to solve the problems associated with durability of weathered granite soil with cement treated was investigated by conducting tests such as unconfined compression test, it's moisture, immers, wet-dry and freeze-thaw curing, mesurement of loss of weight with wet-dry and freeze-thaw by KS F criteria and CBR test with moisture curing on the five soil samples different in weathering and mineral composition. The experimental results are summarized as follows; The unconfined compressive strength was higher in moisture curing rather than in the immers and wet-dry, while it was lowest in freeze-thaw. Decreasing ratio of unconfined compressive strength in soil-cement mixtures were lowest in optimum moisture content or in the dry side rather than optimum moisture content with freeze-thaw. The highly significant ceofficient was obtained between the cement content and loss of weight with freeze-thaw and wet-dry. It was possible to obtain the durability of soil-cement mixtures, as the materials of base for roads, containing above 4 % of cement content, above 3Okg/cm$_2$ of unconfined compressive trength with seven days moisture curing or 12 cycle of freeze-thaw after it, above 100% of relative unconfined compressive strength, 80% of index of resistance, below 14% of loss of weight with 12 cycle of wet-dry and above 1. 80g/cm$_2$ of dry density.

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Properties and pozzolanic reaction degree of tuff in cement-based composite

  • Yu, Lehua;Zhou, Shuangxi;Deng, Wenwu
    • Advances in concrete construction
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    • v.3 no.1
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    • pp.71-90
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    • 2015
  • In order to investigate the feasibility and advantage of tuff used as pozzolan in cement-based composite, the representative specimens of tuff were collected, and their chemical compositions, proportion of vitreous phase, mineral species, and rock structure were measured by chemical composition analysis, petrographic analysis, and XRD. Pozzolanic activity strength index of tuff was tested by the ratio of the compression strength of the tuff/cement mortar to that of a control cement mortar. Pozzolanic reaction degree, and the contents of CH and bond water in the tuff/cement paste were determined by selective hydrochloric acid dissolution, and DSC-TG, respectively. The tuffs were demonstrated to be qualified supplementary binding material in cement-based composite according to relevant standards. The tuffs possessed abundant $SiO_2+Al_2O_3$ on chemical composition and plentiful content of amorphous phase on rock texture. The pozzolanic reaction degrees of the tuffs in the tuff/cement pastes were gradually increased with prolongation of curing time. The consistency of CH consumption and pozzolanic reaction degree was revealed. Variation of the pozzolanic reaction degree was enhanced with the bond water content and relationship between them appeared to satisfy an approximating linear law. The fitting linear regression equation can be applied to mutual conversion between pozzolanic reaction degree and bond water content.

Influences of Chlorides on the Whiteness in White Portland Cement (백시멘트의 백색도에 미치는 염화물의 영향)

  • 한기성;최상흘;서일영
    • Journal of the Korean Ceramic Society
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    • v.13 no.2
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    • pp.3-7
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    • 1976
  • Influences of chlorides(CaCl2, MgCl2, NaCl) on the colouring effect of Fe component in white portland cement was investigated. Chlorides enhance the whiteness of the white portland cement owing to volatilization of Fe2O3 and translation of ferrite composition toward C2F. This translation is caused by consumption of alumina at the formation of C12A7, the formation of which is promoted in the presence of chloride. With decrease of p in ferrite composition C6F1-pAp, transfer of Fe3+ from 4 to 6 coordinated cite is occurred, and as a result, whiteness is raised. Hydration process of the cement containing a small amount of chloride differs little from the one without chloride.

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Mixture Design and Its Application in Cement Solidification for Spent Resin

  • Gan, Xueying;Lin, Meiqing;Chen, Hui
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2004.02a
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    • pp.28-41
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    • 2004
  • The study is aimed to assess the usefulness of the mixture design for spent resin immobilization in cement. Although a considerable amount of research has been carried out to determine the limits for the composition of an acceptable resin-cement mixture, no efficient experimental strategy exists that explores the full properties of waste form against composition relationship. In order to gain an overall view, this report introduces the method of mixture design and mixture analysis, and describes the design of experiment of the 5-component mixture with the constraint conditions. The mathematic models of 28-day compressive strength varying with the ingredients are fitted, and the main effect and interaction effect of two ingredients are identified quantitatively along with the graphical interpretation using the response trace plot and contour plots.

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