• Title/Summary/Keyword: 시멘트 수화반응

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시멘트입도가 강도에 미치는 영향

  • 임창덕
    • Cement Symposium
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    • no.5
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    • pp.88-93
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    • 1977
  • 시멘트 입도는 수화반응 속도에 밀접한 관계가 있으며 이로 인한 강도 발현 및 제반 물리특성에 크게 기여한다. 따라서 제품관리에 Blaine 및 sieve test로서 분말도를 check하고 있는바 이 분말도가 cement 물리특성에 미치는 영향을 실험실적으로 검토하였다.

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Changes in Hydration and Watertightness of Cement Containing Two-Component Fluosilicate Salt Based Chemical Admixture (2성분 규불화염계 혼화제가 첨가된 시멘트의 수화반응 및 수밀성 변화)

  • Kim, Jae-On;Nam, Jae-Hyun;Kim, Do-Su;Khil, Bae-Su;Lee, Byoung-Ky
    • Journal of the Korean Ceramic Society
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    • v.41 no.10 s.269
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    • pp.749-755
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    • 2004
  • Fluosilicic acid ($H_2SiF_6$) is recovered as aqueous solution which absorbs $SiF_4$ produced from the manufacturing of industrial-graded $H_3PO_4$ or HF. Generally, fluosilicate salts prepared by the reaction between $H_2SiF_6$ and metal salts. Addition of fluosilicate salts to cement endows odd properties through unique chemical reaction with the fresh and hardened cement. In this study, two-component fluosilicate salt based chemical admixtures (MZ) of $4\%,\;6\%$, and $8\%$ concentration were prepared by the reaction of $H_2SiF_6$ ($25\pm2\%$) and metal salts. The effect of concentration of MZ at a constant adding ratio on the hydration and watertightness of cement were investigated respectively. In a cement containing MZ, metal fluorides such as $CaF_2$ and soluble silica by hydrolysis were newly formed during hydration. The total porosity of the hardened cement was lower in the presence of U because of packing role of metal fluoride and pozzolanic reaction of soluble $SiO_2$. Consequently, the watertightness of the hardened paste containing MZ was more improved than non-added (plain) due to an odd hydration between cement and MZ.

The Effects of Hydration Retarding of Portland Cement by $MgSiF_6.6H_2O$ (규불화마그네슘에 의한 포틀랜드 시멘트의 수화 지연효과)

  • 한상호;이경희;정성철;김남호
    • Journal of the Korean Ceramic Society
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    • v.34 no.2
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    • pp.163-170
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    • 1997
  • The retarding effects of MgSiF6.6H2O on the hydration of portland cement were studied. The setting time, flow value and compressive strength of mortar were measured and the mechanism of retardation was also studied by ion concentration in solution, SEM, BET, and X-ray diffraction. The results are as follows ; 1. Setting time was delayed by the addition of MgSiF6.6H2O. 2. The flow value of mortar decreases depending upon the amount of MgSiF6.6H2O. 3. The compressive strength was almost same or some increase on 28 days hydration. 4. The main retardation mechanism of MgSiF6 on the hydration of portland cement may be explained by the following hypothesis. MgSiF6 depressing the Ca++ and K+ ion concentration of cement paste solution be-cause of the recrystalization of K2SiF6 and CaF2 phase. The new products of K2SiF6 and CaF2 deposit on the surface of unhydrated cement powder and harzard the mass transfer through these layer. The low con-centration of Ca++, K+ ion in solution was decreasing the hydration rate of portland cement.

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