University of Oulu

J. Yliniemi, B. Walkley, J.L. Provis, P. Kinnunen, M. Illikainen, Nanostructural evolution of alkali-activated mineral wools, Cement and Concrete Composites, Volume 106, 2020, 103472, ISSN 0958-9465,

Nanostructural evolution of alkali-activated mineral wools

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Author: Yliniemi, J.1; Walkley, B.2,3; Provis, J. L.2;
Organizations: 1Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, 90014, Oulu, Finland
2Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin St, Sheffield S1 3JD, United Kingdom
3Department of Chemical and Biological Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin St, Sheffield S1 3JD, United Kingdom
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.7 MB)
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Language: English
Published: Elsevier, 2020
Publish Date: 2019-11-26


Mineral wools are the most widely used building insulation material worldwide. Annually, 2.5 million tonnes of mineral wool waste are generated in the EU alone, and this is a largely unutilised material that is landfilled or incinerated. However, mineral wool wastes are promising precursors for production of alkali-activated cementitious binders due to their favourable chemical and mineralogical composition and high surface area. Alkali-activation is therefore a valuable route for valorisation of large quantities of mineral wool waste. This study resolves the phase assemblage and nanostructure of reaction products formed upon alkali activation of stone wool and glass wool by sodium hydroxide and sodium silicate solutions with X-ray diffraction, electron microscopy and solid state nuclear magnetic resonance spectroscopy experiments probing ²⁷Al and ²⁹Si. The stone wool-based alkali-activated binder comprises an amorphous sodium- and aluminium-substituted calcium silicate hydrate (C-(N-)A-S-H) gel, an amorphous sodium aluminosilicate hydrate (N-A-S-H) gel and small amounts of the layered double hydroxide phase quintinite and zeolite F. The glass wool-based alkali-activated binder comprises an amorphous Ca- and Al-substituted sodium silicate (N-(C-)(A-)S-H) gel. Gel chemical composition and reaction kinetics of alkali-activated mineral wools are shown to be dependent on the activating solution chemistry, with reaction rate and extent promoted by inclusion of a source of soluble Si in the reaction mixture. This work provides the most advanced description of the chemistry and structure of alkali-activated mineral wools to date, yielding new insight that is essential in developing valorisation pathways for mineral wools by alkali activation and providing significant impetus for development of sustainable construction materials.

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Series: Cement & concrete composites
ISSN: 0958-9465
ISSN-E: 1873-393X
ISSN-L: 0958-9465
Volume: 106
Article number: 103472
DOI: 10.1016/j.cemconcomp.2019.103472
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
216 Materials engineering
Funding: The research was performed under the auspices of Geodesign-project funded by the Business Finland and various companies (Boliden Harjavalta Oy, Destamatic Oy, Fortum Power and Heat Oy, Paroc Group Oy, Saint-Gobain Finland Oy, and Suomen Erityisjäte Oy). The experimental work was performed at the University of Sheffield, UK and at the University of Oulu, Finland. Dan Geddes, Dr Oday Hussein, Jarno Karvonen and Elisa Wirkkala are acknowledged for their assistance with some of the laboratory work. Dr Dale Prentice is acknowledged for assistance with SEM-EDX data processing and Dr Sandra van Meurs is acknowledged for her assistance acquiring NMR data. The authors thank the PQ Corporation for generously supplying the sodium silicate solution used in this investigation.
Copyright information: © 2019 The authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.