Synergistic Effect of High Temperature Fly Ash with Fluidized Bed Combustion Fly Ash in Cement Composites

Abstract:

Using high temperature fly ash for his pozzolan properties to cement composite production is known a few years ago. New ways combustion of fossil fuels also creates a new type of fly ash, named fluidized bed combustion fly ash. However, this fly ash has same pozzolan properties as has high temperature fly ash, this type is not using for production of cement composites. Fluidized bed combustion fly ash has highly variable chemical composition but usually it has a higher amount of free CaO together with sulphates. This higher amounts of free CaO after mixing of fluidized bed combustion fly ash with water to some extent becomes an activator for the beginning of the pozzolanic reaction, during which is consumed the extinguished CaO. If there is also present high temperature fly ash in cement composite, it could be accelerated his pozzolanic reaction in the same manner using a fluidized bed combustion fly ash. In this experiment was tested a synergy effect in the use of fluidized bed combustion fly ash with high temperature fly ash as an additive. The experiment was carried out on cement pastes that have been studied in particular the progress of hydration processes, pointing to a possible acceleration of pozzolanic reactions of both types of fly ash.

• Periodical: Key Engineering Materials (Volume 722)
• Pages: 113-118
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.722.113
• Online since: December 2016
• Authors: Martin Ťažký*, Rudolf Hela
• Keywords: CaO, Fluidized Bed Combustion Fly Ash, High Temperature Fly Ash, Pozzolan

References

[1] R. Hela, D. Orsakova, The Mechanical Activation of Fly Ash, in: J. Bujnak, J. Vican (Eds. ),. Concrete and Concrete Structures 2013, Procedia Engineering, Vol 65, 2013, pp.87-93.

DOI: 10.1016/j.proeng.2013.09.016

[2] Bland, A. E., Brown, T., Wheeldon, J., Pressurized fluidized bed combustion ash 1. Construction-related use options, Fuel, Volume 76, Issue 8, June 1997, Pages 733-740, ISSN 0016-2361, http: /dx. doi. org/10. 1016/S0016- 2361(97)00002-1.

DOI: 10.1016/s0016-2361(97)00002-1

[3] T. Robl, K. Mahboub, W. Stevens, R. Rathbone, Fluidized Bed Combustion Ash Utilization: CFBC Fly Ash as a Pozzolanic Additive to Portland Cement Concrete, Coventry University and The University of Wisconsin Milwaukee Centre for by-products utilization, In P. Claisse, E. Ganijan, F. Canpolat, T. Naik, Special Technical Proceedings 2nd International Conference on Sustainable Construction Materials and Technologies, Ancona, Italy, (2010).

DOI: 10.4028/www.scientific.net/kem.629-630.306

[4] Xiang-guo LI, Quan-bin Chen, Kuai-zhong Huang, Bao-guo Ma, Bei Wu, Cementitious properties and hydration mechanism of circulating fluidized bed combustion (CFBC) desulfurization ashes, Construction and Building Materials, Volume 36, November 2012, Pages 182-187, ISSN 0950-0618.

DOI: 10.1016/j.conbuildmat.2012.05.017

[5] R. Hela, J. Maršálová, L. Bodnárová, Fly Ashes Thermal Modification and their Utilization in Concrete, in: F. Bontempi  (Ed. ), System-based Vision for Strategic and Creative Design, Vols 1-3, Roma, 2003, p.1649 – 1653.

[6] M.A. Glinicki, M. Zieliński, The influence of CFBC fly ash addition on phase composition of air-entrained concrete, Bulletin of The Polish Academy of Sciences-technical Sciences, Vol. 56, no. 1, 2008, pp.45-52.

[7] Ťažký, M., Hela, R. Elimination of Negative Influence of Fluidized Bed Combustion Fly Ash on Viscosity of Cement Mix, In Materials Science Forum, Vol. 865, 2016, pp.12-16.

DOI: 10.4028/www.scientific.net/msf.865.12