Effect of Fluidized Bed Ash on the Thermodynamic Stability of Hydraulic Binders

Abstract:

Fluidized bed ash, which is the youngest industrial waste can be considered on the basis of research, a high-quality secondary raw material base which can be easily used in the production of Portland cements and, in general, other hydraulic binders. Regarding the direct effect of anhydrite on the course of hydrating mixed cement with the fluidized fly ash and the consequent behaviour of the originated cement stone, its reaction with clinker materials on the mentioned Aft (Al₂O₃–Fe₂O₃-–tri) phase is clear. The creation of AFt phases, if they originate additionally, due to their morphology, is accompanied by significant volume changes which may lead to deformation up to the destruction of the cement stone. Some foreign publications show the possibility of the transformation of this thermo-dynamically unstable mineral into the further mineral from the group AFt phase, which is thaumasite, Ca₃Si (CO₃)(SO₄)(OH)₆^.12H₂O.

• Periodical: Materials Science Forum (Volume 908)
• Pages: 21-25
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.908.21
• Online since: October 2017
• Authors: Karel Kulísek, Dominik Gazdič, Karel Dvořák
• Keywords: Cement, Ettringite, Fluidized Ash, Hydraulic Binders, Thaumasite

References

[1] MATSCHEI, T. et al.: Thermodynamic properties of Portland cement hydrates in the system CaO–Al2O3–SiO2–CaSO4–CaCO3–H2O, Cement and Concrete Research 37 (2007) p.1379–1410.

DOI: 10.1016/j.cemconres.2007.06.002

[2] GAZE, M. E.: The effects of varying gypsum content on thaumasite formation in a ce-ment: lime: sand mortar at 5°C, Cement and Concrete Research, Vol. 27, No. 2, pp.259-265, (1997).

DOI: 10.1016/s0008-8846(96)00203-7

[3] BELLMANN, F. - STARK, J.: The role of calcium hydroxide in the formation of thaumasite, Cement and Concrete Research 38 (2008) 1154–1161.

DOI: 10.1016/j.cemconres.2008.04.005

[4] KOHLER, S. - HEINZ, D. - URBONAS, L.: Urbonas Effect of ettringite on thaumasite formation, Ce-ment and Concrete Research 36 (2006) 697 – 706.

DOI: 10.1016/j.cemconres.2005.11.006

[5] FRIDRICHOVÁ, M., et al.: Thermodynamic Stability of Ettringite Formed by Hydration of Ye'elimite Clinker. Advances in Materials Science and Engineering, 2016, vol. 2016, no. 30, pp.1-7. ISSN: 1687-8434.

DOI: 10.1155/2016/9280131

[6] MOKRÁ, J., et al.: Long- term Observation of Yeelimite Clinker Hydration in Environment of Saturated Water Vapour. In Ecology and new building materials and products 2016. Procedia Engineering: Else-vier, 2016. pp.94-99. ISSN: 1877-7058.

DOI: 10.1016/j.proeng.2016.07.385

[7] FRIDRICHOVÁ, M., et al.: Potential to reduce CO2 emissions when producing hydraulic binders. Ce-ment International, 2014, vol. 12/ 12, no. 4/ 2014, pp.76-84. ISSN: 1610-6199.

[8] GEMRICH, J., et al.: Synthesis of pure thaumasite, Applied Mechanics and Materials Vol. 723 (2015) pp.456-459, Trans Tech Publications, Switzerland, ISSN: 1662-7482.

DOI: 10.4028/www.scientific.net/amm.723.456