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Carbonation mechanism of different kind of C-S-H : rate and products

Bei Wu and Guang Ye (UGent)
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Abstract
During the carbonation of cement paste blended with supplementary cementitious materials, the C-S-H with different Ca/Si ratios, formed from the hydration and pozzolanic reactions, are the major calcium-bearing phases which react with CO2. Therefore, it’s important to study the carbonation mechanism of different C-S-H phases. In this paper, the pure C-S-H phases (Ca/Si ratio: 0.66 to 2.0) were synthesized and used for the accelerated carbonation test. Synthesized C-S-H phases with different Ca/Si ratio were identified by X-ray diffraction and 29Si nuclear magnetic resonance. The carbonation rate and products of different C-S-H phases are also determined. The results show that pure C-S-H phases with different Ca/Si ratio (lower than 1.40) can be synthesized in the lab. The structure of synthesized C-S-H is similar to the C-S-H(I) reported by Taylor. The mean chain length of the C-S-H decreases dramatically when the Ca/Si ratio increases from 0.66 to 1.40, then it keeps no change. The portlandite appears in the products when the designed Ca/Si ratio is over 1.40. The C-S-H with lower Ca/Si ratio is decomposed faster than that with a higher Ca/Si ratio. All the C-S-H phases are fully decomposed to CaCO3 and silica gel after 3 days’ accelerated carbonation.

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Chicago
Wu, Bei, and Guang Ye. 2016. “Carbonation Mechanism of Different Kind of C-S-H : Rate and Products.” In Concrete with Supplementary Cementitious Materials, ed. Ole M Jensen, Konstantin Kovler, and Nele De Belie, RILEM PRO 113:163–272. Paris, France: RILEM.
APA
Wu, Bei, & Ye, G. (2016). Carbonation mechanism of different kind of C-S-H : rate and products. In Ole M Jensen, K. Kovler, & N. De Belie (Eds.), Concrete with Supplementary Cementitious Materials (Vol. RILEM PRO 113, pp. 163–272). Presented at the Int. RILEM Conference on Materials, Systems and Structures in Civil Engineering 2016 - Segment on Concrete with Supplementary Cementitious Materials, Paris, France: RILEM.
Vancouver
1.
Wu B, Ye G. Carbonation mechanism of different kind of C-S-H : rate and products. In: Jensen OM, Kovler K, De Belie N, editors. Concrete with Supplementary Cementitious Materials. Paris, France: RILEM; 2016. p. 163–272.
MLA
Wu, Bei, and Guang Ye. “Carbonation Mechanism of Different Kind of C-S-H : Rate and Products.” Concrete with Supplementary Cementitious Materials. Ed. Ole M Jensen, Konstantin Kovler, & Nele De Belie. RILEM PRO 113. Paris, France: RILEM, 2016. 163–272. Print.
@inproceedings{8531148,
  abstract     = {During the carbonation of cement paste blended with supplementary cementitious materials,
the C-S-H with different Ca/Si ratios, formed from the hydration and pozzolanic reactions, are
the major calcium-bearing phases which react with CO2. Therefore, it{\textquoteright}s important to study the
carbonation mechanism of different C-S-H phases. In this paper, the pure C-S-H phases
(Ca/Si ratio: 0.66 to 2.0) were synthesized and used for the accelerated carbonation test.
Synthesized C-S-H phases with different Ca/Si ratio were identified by X-ray diffraction and
29Si nuclear magnetic resonance. The carbonation rate and products of different C-S-H phases
are also determined. The results show that pure C-S-H phases with different Ca/Si ratio (lower
than 1.40) can be synthesized in the lab. The structure of synthesized C-S-H is similar to the
C-S-H(I) reported by Taylor. The mean chain length of the C-S-H decreases dramatically
when the Ca/Si ratio increases from 0.66 to 1.40, then it keeps no change. The portlandite
appears in the products when the designed Ca/Si ratio is over 1.40. The C-S-H with lower
Ca/Si ratio is decomposed faster than that with a higher Ca/Si ratio. All the C-S-H phases are
fully decomposed to CaCO3 and silica gel after 3 days{\textquoteright} accelerated carbonation.},
  author       = {Wu, Bei and Ye, Guang},
  booktitle    = {Concrete with Supplementary Cementitious Materials},
  editor       = {Jensen, Ole M and Kovler, Konstantin and De Belie, Nele},
  isbn         = {978-2-35158-180-3},
  language     = {eng},
  location     = {Lyngby (Denmark)},
  pages        = {163--272},
  publisher    = {RILEM},
  title        = {Carbonation mechanism of different kind of C-S-H : rate and products},
  volume       = {RILEM PRO 113},
  year         = {2016},
}