University of Oulu

Ohenoja, K., Wigren, V., Österbacka, J. et al. Mechanically Treated Fly Ash from Fluidized Bed Combustion of Peat, Wood, and Wastes in Concrete. Waste Biomass Valor 11, 3071–3079 (2020).

Mechanically treated fly ash from fluidized bed combustion of peat, wood, and wastes in concrete

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Author: Ohenoja, Katja1; Wigren, Valter2; Österbacka, Jan3;
Organizations: 1Fibre and Particle Engineering, Faculty of Technology, University of Oulu, PO Box 4300, 90014, Oulu, Finland
2Renotech Oy, Sampsankatu 4B, PO Box 20520, Turku, Finland
3Fortum Waste Solutions Oy, Kuulojankatu 1, PO Box 181, 11101, Riihimäki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
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Language: English
Published: Springer Nature, 2020
Publish Date: 2020-02-26


Fly ash generation in fluidized bed combustion (FBC) is a critical issue in many countries due to its disposal is becoming increasingly restricted and expensive. Because of this, there is a demand for applications in which these types of fly ashes could be utilized efficiently. One promising use for FBC fly ashes is as a cement replacement material in mortar and concrete. The current concrete regulations do not allow the use FBC fly ash as a supplementary cementitious material, but it can be expected to be included in the standards in the future. The properties of FBC fly ashes typically do not fulfill the values set in the standards as such. This study aimed to establish whether the properties of fly ashes from FBC of peat, wood, and wastes can be modified by mechanical classification and grinding so that they meet the requirements of the standards. The sulfate and chloride content, the sum of the main components (Si, Al, Fe), and the fineness of material were analyzed before and after the classification and grinding processes. In addition, the mortar specimens were prepared by using the processed fly ash as a cement replacement material. It was found that air jet classification is an effective fractionating method for fly ashes that effectively removes sulfate and chloride into fine fraction. Classified and ground fly ashes are potential alternative cement replacement materials. It is possible to achieve 80% of the control sample’s compressive strength and 90% of the control sample’s flexural strength for mortars containing 20% of classified and ground FBC fly ashes.

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Series: Waste and biomass valorization
ISSN: 1877-2641
ISSN-E: 1877-265X
ISSN-L: 1877-2641
Volume: 11
Pages: 3071 - 3079
DOI: 10.1007/s12649-019-00615-y
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: Open access funding provided by University of Oulu including Oulu University Hospital. This study was supported by the Finnish Funding Agency for Technology and Innovation and the following Finnish companies: Boliden Harjavalta Oy, Ekokem Palvelu Oy, Fortum Power and Heat Oy, Helen Oy, Jyväskylän Energia Oy, Kemira Chemicals Oy, Metsä Board Oyj, Napapiirin Energia ja Vesi Oy, Nordkalk Oy Ab, Paroc Group Oy, SSAB Europe Oy, Stora Enso Oyj, UPM-Kymmene Oyj, and Valmet Technologies Oy.
Copyright information: © The Author(s) 2019. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.