Keywords :
Alkali activation; Alternative activator; Blast furnace slag; Cleaner production; Life cycle impact assessment; Alkali activated slags; Alkali-activated binder; Environmental footprints; Ground granulated blast-furnace slag (GGBFS); Industrial residues; Steel-making wastes; Steelmaking process; Renewable Energy, Sustainability and the Environment; Environmental Science (all); Strategy and Management; Industrial and Manufacturing Engineering; General Environmental Science; Building and Construction
Abstract :
[en] In this study, the use of desulphurization dust (DeS-dust) generated as a waste material during steel-making process, as an alternative activator to commercial sodium hydroxide in ground granulated blast furnace slag (GGBFS) alkali activation is proposed. The main objective was to decrease the environmental footprint of alkali-activated materials through the reuse of industrial residues. Microsilica was added to increase the amount of soluble silica and enhance the properties of the investigated binders. The results indicate that binders from alternative activator performed better, achieving a 28 days maximum strength of 33 MPa compared to 25 MPa for the sodium hydroxide activated slag. Microsilica addition to the optimum mixes reduces the rate of efflorescence and increases the setting time. Also, microstructural studies using scanning electron microscopy (SEM), x-ray diffraction (XRD) and thermogravimetric analysis (TGA) show both samples having comparable gel formation and structure. Life cycle impact assessment shows significant savings that can be made using alternative activators over sodium hydroxide activated slag. Through the use of this waste material as alternative activator in alkali-activated binders, an environmentally friendly, and cleaner production of alkali-activated binders can be achieved having comparable or superior performance as the reference binder activated with commercial sodium hydroxide.
Funding text :
This work was done as a part of SYMMET project supported by the Business Finland and several Finnish companies: Boliden Harjavalta Oy , Boliden Kokkola Oy , Luxmet Oy , Outokumpu Stainless Oy , Outotec , Owatec Oy , SSAB Europe Oy , Tapojärvi Oy , and Timegate Instruments Oy . P.K. acknowledges financial support from Academy of Finland (grants 322085 , 326291 and 329477 ). Johannes Kaarre is acknowledged for his contribution to the laboratory work.
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