Synthesis of cement based CaO–Al2O3–SiO2–H2O (CASH) hydroceramics at 200 and 250 °C: Ex-situ and in-situ diffraction

Meller, Nicola; Kyritsis, Konstantinos; Giriat, G.

doi:10.1016/j.cemconres.2007.03.006

Cited by 47 publications

(22 citation statements)

References 22 publications

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“…and Ríos et al . However, here, it was found that α‐C 2 SH only exist between 12 h and 28 h. Several previous studies have found that α‐C 2 SH was metastable and transformed into another phase with increasing time and temperature ,. Therefore, it is possible that the disappearance of α‐C 2 SH was because α‐C 2 SH was transformed into another phase such as tobermorite.…”

Section: Resultsmentioning

confidence: 99%

Study of K‐Feldspar and Lime Hydrothermal Reaction at 190 °C: Phase, Kinetics and Mechanism with Reaction Time

2018

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An artificial silicate composite material prepared by the hydrothermal reaction of K‐feldspar and lime, showed excellent performance in remediating the soil. To elucidate the physicochemical properties of the artificial silicate composite material, K‐feldspar and lime were reacted in mild hydrothermal conditions (T=190 °C; P∼12.4 atm; t=0∼36 h). The hydrothermal product was systematically investigated using various techniques such as X‐ray powder diffraction (XRPD), scanning electron microscopy, and inductively coupled plasma‐optical emission spectrometry (ICP–OES). Quantitative evaluation of the extent of reaction by ICP–OES and XRPD methods enabled the analysis of hydrothermal evolution with prolonged time. The hydrothermal treatment of K‐feldspar with lime exhibits complex product phases, including leftover K‐feldspar, calcium hydroxide, calcite, grossular, tobermorite, alpha‐dicalcium silicate hydrate, potassium carbonate, bütschliite, and amorphous calcium silicate hydrate. The analysis of the reaction reveals that the K‐feldspar dissolution showed a clear transition, with the hydrothermal reaction beginning to slow down after 20 h. The slowdown of the K‐feldspar dissolution was essentially caused by different reaction kinetics and mechanisms before and after 20 h. The study yields vital and valuable insights into comprehending the chemistry and mineralogy of the artificial silicate composite material and producing a multielement reservoir from potassium‐rich rocks.

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Section: Resultsmentioning

confidence: 99%

Study of K‐Feldspar and Lime Hydrothermal Reaction at 190 °C: Phase, Kinetics and Mechanism with Reaction Time

2018

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“…(Table IV). 3,4,7 Here we report data concerning only the hydrogarnets. As can be seen from Table IV the mineralogy of the CASH system is complicated.…”

Section: Resultsmentioning

confidence: 99%

Chemistry and Morphology of Hydrogarnets Formed in Cement‐Based CASH Hydroceramics Cured at 200° to 350°C

Kyritsis

Meller

2009

Journal of the American Ceramic Society

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We have studied the chemistry and the morphology of hydrogarnet crystals produced in cement‐based hydroceramic materials at elevated temperatures (200°–350°C) with silica and alumina additions. Such materials lie within the hydrothermal CaO–Al2O3–SiO2–H2O (CASH) system. Hydrogarnet Ca3Al2(SiO4)3−y(OH)4y is the dominant aluminum bearing phase formed and its composition is influenced mainly by the curing temperature and to a lesser degree by the addition of silica. The composition parameter y was estimated by Rietveld refinement of X‐ray diffraction (XRD) data. Electron probe microanalysis (EPMA) shows that the hydrogarnets incorporate minor elements such as Fe, Mg, and S. EPMA data confirmed the hydrogarnet composition estimated from XRD. Both octahedral and icositetrahedral forms are observed. The icositetrahedral form is associated with higher minor element content.

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“…Also truscottite forms instead of gyrolite when adding small amounts of alumina and high amounts of silica flour. As can be seen from Table III, the mineralogy of this system (CASH) is complicated and it is described in more detail elsewhere 7,9,10 . Here we focus on the significance of the different minerals on the engineering properties of these materials.…”

Section: Resultsmentioning

confidence: 99%

“…There have been several recent attempts to design cements that are more durable at higher temperatures. Meller et al 7–10 have designed slurries based on the CaO−Al 2 O 3 −SiO 2 −H 2 O (CASH) system, with the aim of developing formulations suitable for geothermal and deep, hot oil wells. These formulations contain minerals that occur in nature and hence have the potential properties required to be good well sealants, i.e.…”

Section: Introductionmentioning

confidence: 99%

Relationship Between Engineering Properties, Mineralogy, and Microstructure in Cement‐Based Hydroceramic Materials Cured at 200°–350°C

Kyritsis

Bentz

Meller

et al. 2009

Journal of the American Ceramic Society

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Cement‐based materials used to seal geothermal or deep oil wells are exposed to severe conditions. Optimizing engineering properties such as strength and permeability is therefore very important. We have synthesized hydroceramic materials for such applications based on the CaO−Al2O3−SiO2−H2O (CASH) system and cured them over a range of temperatures (200°–350°C). Depending on initial composition and curing temperature, hydroceramics of complex and diverse mineralogy and microstructure are formed. The minerals found include portlandite, jaffeite, xonotlite, gyrolite, 11 Å tobermorite, truscottite, hydrogarnet, and calcium aluminum silicate hydrate. These cement‐based hydroceramic materials develop complicated pore structures, which strongly affect bulk properties. We report the compressive strength and permeability of these materials and show how these bulk engineering properties are related to microstructure. The compressive strength was found to be in the range 2–52 MPa and the intrinsic permeability in the range 0.5 × 10−17 to 3300 × 10−17 m2. Scanning electron microscopy (SEM) was used for imaging the hydroceramic microstructures. Further, we have computed the intrinsic permeability from 2‐D SEM images by using the Stokes equation solver, Permsolver, applied to reconstructed 3‐D images and the results are shown to be in good agreement with experimentally determined values.

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Synthesis of cement based CaO–Al2O3–SiO2–H2O (CASH) hydroceramics at 200 and 250 °C: Ex-situ and in-situ diffraction

Cited by 47 publications

References 22 publications

Study of K‐Feldspar and Lime Hydrothermal Reaction at 190 °C: Phase, Kinetics and Mechanism with Reaction Time

Study of K‐Feldspar and Lime Hydrothermal Reaction at 190 °C: Phase, Kinetics and Mechanism with Reaction Time

Chemistry and Morphology of Hydrogarnets Formed in Cement‐Based CASH Hydroceramics Cured at 200° to 350°C

Relationship Between Engineering Properties, Mineralogy, and Microstructure in Cement‐Based Hydroceramic Materials Cured at 200°–350°C

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