• Title/Summary/Keyword: Hydration rate

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Hydration Reaction Properties of Concrete With Binders and Admixtures (결합재와 혼화재 종류에 따른 콘크리트의 수화반응 특성)

  • Cho, Il-Ho;Sung, Chan-Yong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.50 no.2
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    • pp.27-34
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    • 2008
  • Recently, owing to the development of industry and improvement of building techniques, concrete structures are becoming larger and higher. This study was performed to analyze hydration reation properties of concrete with binders and admixtures, such as OPC, low heat cement, belite rich cement, slag powder, lime powder and fly ash. To investigate effects of PC type superplasticizer on the hydration, experiments involving FT-IR, XRD, DSC, SEM were analyzed at the curing age 1day, 3days and 28days. The hydration reaction rate of OPC concrete slightly delayed at the curing age 1day, blast furnace slag powder and fly ash were more effective. BRC and LHC concretes can be used for concrete structures in winter season.

Carbonation of Portland Cement Studied by Diffuse Reflection Fourier Transform Infrared Spectroscopy

  • Ylmen, Rikard;Jaglid, Ulf
    • International Journal of Concrete Structures and Materials
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    • v.7 no.2
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    • pp.119-125
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    • 2013
  • Carbonation is a natural ageing process for cement. This study focuses on how the carbonation rate varies with selected hydration times and atmospheric conditions during the early stages of reacting dried cement paste. Diffuse reflection Fourier transform infrared spectroscopy is shown to be a suitable technique to monitor the formation of carbonates in cement. Combined with a previously developed freeze drying technique, carbonation can be studied at specific hydration stages. In ambient air both calcium hydroxide and calcium silicate hydrate (C-S-H) in cement are carbonated. Increased hydration time enhances the carbon dioxide uptake, which indicates that the calcium in the hydration products reacts more easily than the calcium in the clinker phase. In a humid $CO_2$ atmosphere, the carbonation process is so pronounced that it decomposes C-S-H into calcium carbonate and silica. In a moist $N_2$ atmosphere no carbonation occurs, but the sulfate chemistry of the cement seems to be affected due to the formation of ettringite.

Reduction of Hydration heat of FA concrete using Coal Gasification Slag for Mixed Fine Aggregate (석탄 가스화 용융 슬래그를 혼합 잔골재로 사용한 FA 치환 콘크리트의 수화열 저감)

  • Han, Jun-Hui;Lee, Young-Jun;Choi, Il-Kyung;Kim, Jung;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.11a
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    • pp.79-80
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    • 2019
  • This study was intended to examine the possibility of reducing hydration heat by FA substitution and combination of slag (CGS) from coal gasification power generation (IGCC) with mixed aggregate for concrete. The analysis results showed good results if liquidity increases as the ratio of CGS increases, air volume decreases, and compressive strength is mixed up to 25% in the residual aggregate. The results showed that the heat of hydration was reduced compared to plain due to the boron content of CGS as the CGS substitution rate increased, but it was larger due to the combination with FA substitution. It was found that the heat of hydration was reduced.

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Effects of cellulose nanocrystals and graphene oxide on hydration heat of cement paste (셀룰로오스 나노크리스탈과 산화그래핀이 시멘트 페이스트의 수화열에 미치는 영향)

  • Lee, Yun-Kyung;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.189-190
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    • 2023
  • In this study, the compressive strength and hydration heat of cement paste mixed with cellulose nanocrystal(CNC) and graphene oxide (GO) were evaluated. The difference was compared by mixing 0.1 vol.% ~0.4 vol.% of CNC and 0.05 wt.% ~ 0.1 wt.% of GO in a cement paste with a water cement ratio of 0.3. As a result, it was confirmed that the compressive strength increased as CNC and GO were mixed respectively, and then the compressive strength decreased when the appropriate mixing rate was exceeded. In the hydration heat measurement, there was no significant difference when only CNC was mixed, but it was confirmed that the hydration heat decreased as the amount of CNC mixing increased when used in combination with GO.

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Modeling of ultimate value and kinetic of compressive strength and hydration heat of concrete made with different replacement rates of silica fume and w/b ratios

  • Djezzar, Mahdjoub;Ezziane, Karim;Kadri, Abdelkader;Kadri, El-Hadj
    • Advances in concrete construction
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    • v.6 no.3
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    • pp.297-309
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    • 2018
  • The objective of this study was to evaluate the influence of silica fume (SF) on the hydration heat and compressive strength of concrete. Portland cement with w/(c+sf) ratios varying between 0.25 to 0.45 was substituted by 10%, 20% and 30% of SF by mass. A superplasticizer was used to maintain a fluid consistency of the concrete. The heat of hydration was monitored continuously by a semi-adiabatic calorimetric method for 10 days at $20^{\circ}C$. Compressive strengths are tested for each mixture until age of 180 days. The results show that silica fume considerably influences the evolution and the ultimate values of the compressive strengths as well as the hydration heat especially for 10% rate. The w/b ratio has a considerable effect where its decrease modifies compressive strength and hydration heat more than silica fume. The correlation of the obtained results allows deducing of ultimate properties as well as the ages to reach half of their values. The correlation coefficients are close to unity and reflect the judicious choice of these relationships to be used to predict compressive strength and hydration heat.

Precision Measurement of the Hydration of Mortar by Ultrasonic and Dielectric Method (초음파 및 유전성을 이용한 모르타르(Mortar) 수화(Hydration) 과정의 정밀측정)

  • Han, E.K.;Lee, M.H.;Kim, S.Y.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.9 no.1
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    • pp.56-68
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    • 1989
  • Recently, there are many fields have been required for the precision measurements, as an advanced example of which, a precise change of inner structure during the hydration process of mortar was observed by ultrasonic and dielectric measurements. The results show that it is possible to determine the safety of mortar and mixing ratio, and strength growth and shrinkage rate by heat evolution.

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A study on the characteristic of hydration reaction in $CaO-Al_2O_3-SiO_2$ system glass ($CaO-Al_2O_3-SiO_2$계 유리의 수화반응특성)

  • 조재우;김승진;김영근;손진군
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.289-292
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    • 1999
  • The charateristic of hydration reaction was studied in CaO-Al2O3-SiO2 system glass. As a result, the rate of heat liberation curves of synthestized glass becomes fixed after having increased by degrees. And it is decreasing after having increased suddenly. It was found that the total heat liberation with hydration for synthesized glass has a close relationship with the formation amount of ettringite.

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An Analysis on the Effect of Reinforced Steel Bar to the Beat of Hydration in the Concrete Structures (철근의 영향을 고려한 콘크리트 구조물의 수화열 해석)

  • 양옥빈;윤동용;민창식
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.35-40
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    • 2002
  • This paper presents a numerical study on the heat of hydration of reinforced concrete with different steel ratio. And this study intends to determine the effect of the steel on the variation of temperatures during hydration. In order to do this, the thermal analyses of the pier-foundation models were carried out using the finite element analysis program, ADINA. As the steel rate increased, the maximum temperature and the internal-external temperature difference decreased.

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Evaluation of Self-Healing Performance Using Hydration Model of Portland Cement and Clinker (포틀랜드시멘트와 클링커의 수화모델을 이용한 자기치유 성능평가)

  • Choi, Sang-Hyeon;Park, Byoung-Sun;Cha, Soo-Won
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.1
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    • pp.81-87
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    • 2020
  • Crack control is essential to increase the durability of concrete significantly. Healing of crack can be controlled by rehydration of unreacted clinkers at the crack surface. In this paper, by comparing the results of isothermal calorimetry test and regression analysis, the Parrot & Killoh's cement hydration model was verified and clink er hydration model was proposed. The composition and quantification of hydration products were simulated by combining kinematic hydration model and thermodynamic model. Hydration simulation was conducted using the verified and proposed hydration model, and the simulation was performed by the substitution rate of clink er. The type and quantity of the final hydration product and healing product were predicted and, in addition, the optimal cementitious material of self-healing concrete was selected using the proposed hydration model.

Measurement of the Hydration Reaction Rate of Supersulphated Slag Cement by Selective Extraction Methods (선택추출법에 의한 고황산염슬래그 시멘트의 수화반응속도의 측정)

  • 송종택;대문정기(大門正機)
    • Journal of the Korean Ceramic Society
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    • v.19 no.1
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    • pp.19-23
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    • 1982
  • The technique to determine the components in the supersulphated slag cement is discussed by several selective extraction analyses. Accordingly, the rate of hydration reaction of supersulphated slag cement could be quantitatively measured by the following 3 kinds of the selective extraction analyses. (1) Determination of unreacted slag - a salicylic acid, acetone.methanol solution (2) Determination of free $CaSO_4$ - a half saturated lime water (3) Determination of free $Ca(OH)_2$ - glycerine.alcohol solution

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