Synthetic Preparation and Properties of Ettringite

Abstract:

This paper deals with the verification of the possibility of preparing synthetic ettringite in a way of direct addition of aluminum sulfate and calcium hydroxide as an alternative to the hydration of yeelimite. The stability of the resulting system was studied using the X-ray diffraction (XRD) and differential thermal analysis (DTA) in two different environments, namely in a laboratory environment and the environment of saturated water vapour. The evaluations of X-ray diffraction analysis and thermal analysis show that in the ettringite sample stored in the laboratory environment, evaporation of molecular water and subsequent transformation of ettringite into metaettringite or monosulfate can occur over time. Conversely, exposition of saturated water vapour environment can lead to saturation of the system by free calcium ions due to the slow dissociation of calcium carbonate, and thereby increase the amount of ettringite at the expense of gypsum and aluminum amorphous phase. To verify the above, it is recommended long-term monitoring of samples exposed in monitored environments.

• Periodical: Key Engineering Materials (Volume 760)
• Pages: 49-54
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.760.49
• Online since: January 2018
• Authors: Marcela Fridrichová, Dominik Gazdič*, Jana Mokrá, Karel Dvořák
• Keywords: Calcite, Differential Thermal Analysis (DTA), Ettringite, Gypsum, Laboratory Environment, Metaettringite, Monosulfate, Saturated Water Vapour Environment, X-Ray Diffraction (XRD)

References

[1] J. Hlaváč, Základy technologie silikátů, first ed., SNTL-Nakladatelství technické literatury, Praha, (1981).

[2] Portland cement association, Ettringite Formation and the Performance of Concrete, Concrete information. (2001).

[3] W. Müllauer, R.B. Beddoe, D. Heinz, Sulfate attack expansion mechanisms, Cement and Concrete Research. 52 (2013) 208-215.

DOI: 10.1016/j.cemconres.2013.07.005

[4] H.F.W. Taylor, C. Famy, K.L. Scrivener, Delayed ettringite formation, Cement and Concrete Research. 31 (2001) 683-693.

DOI: 10.1016/s0008-8846(01)00466-5

[5] H. Siedel, S. Hempel, R. Hempel, Secondary ettringite formation in heat treated portland cement concrete: Influence of different w/c ratios and heat treatment temperatures, Cement and Concrete Research. 23 (1993) 453-461.

DOI: 10.1016/0008-8846(93)90110-u

[6] Q. Zhou, F.P. Glasser, Thermal stability and decomposition mechanism of ettringite at <120°C. Cement and Concrete Research. 31 (2001) 1333-1339.

DOI: 10.1016/s0008-8846(01)00558-0

[7] V. Šatava, O. Vepřek, Thermal decomposition of ettringite under hydrothermal compositions, J. Am. Ceram. Soc. 58 (1975) 357-359.

[8] K. Ogava, D.M. Roy, C4A3S hydration, ettringite, and its expansion mechanism: I. Expansion; ettringite stability, Cement and Concrete Research. 11 (181) 741-750.

DOI: 10.1016/0008-8846(81)90032-6

[9] C. Hall, P. Barnes, A.D. Bullimore, A.C. Jupe, X. Turrillas, Thermal decomposition of ettringite Ca6[Al(OH)6]2(SO4)3. 26H2O. J. Chem. Soc. 92 (1996) 2125-2129.

DOI: 10.1039/ft9969202125

[10] H.F.W. Taylor, Cement chemistry, ThomasTelford, London, (1997).

[11] J. Pourchez, F. Valdivieso, P. Grosseau, R. Guyonnet, B. Guilhot, Kinetic modelling of the thermal decomposition of ettringite into metaettringite, Cement and Concrete Research. 36 (2006) 2054-(2060).

DOI: 10.1016/j.cemconres.2006.06.007

[12] M. Santhanam, M.D. Cohen, J. Olek, Sulfate attack research – whither now? Cement and Concrete Research. 31 (2001) 845-851.

DOI: 10.1016/s0008-8846(01)00510-5

[13] J. Mokrá, K. Kulísek, D. Gazdič, M. Fridrichová, Long-term Observation of Yeelimite Clinker Hydration in Environment of Saturated Water Vapour, Procedia Engineering. 151 (2016) 94-99.

DOI: 10.1016/j.proeng.2016.07.385