Abstract
Achieving sustainable zero-waste and carbon neutral solutions that contribute to a circular economy is critically important for the long-term prosperity and continuity of traditional carbon-based energy industries. The Estonian oil shale (OS) sector is an example where such solutions are more than welcome. The combustion of OS generates a continuous flow of ashes destined to landfills. In this study, the technical feasibility of producing monolith building materials incorporating different OS ashes from Estonia was evaluated. Three binder systems were studied: self-cementation of the ashes, ceramic sintering in clay brick production and accelerated carbonation of OS ash (OSA) compacts. Results showed that most of the OSAs studied have low self-cementitious properties and these properties were affected by ash fineness and mineralogical composition. In case of clay bricks, OSA addition resulted in a higher porosity and improved insulation properties. The carbonated OSA compacts showed promising compressive strength. Accelerated carbonation of compacted samples was found to be the most promising way for the future utilization of OSAs as sustainable zero-waste and carbon neutral solution.
Highlights
New initiatives by the European Commission aim at reducing air and water emissions and extensively encourage innovation in waste or residue recovery using “Best-Available Technologies”(BAT) that promote transitions towards green energy production under the principles of circular economy [1]
The current study includes three sub-studies of oil shale ash utilization in building materials; first sub-study is testing of self-cementing properties of all the currently generated OS ash (OSA), second sub-study is the clay brick production with oil shale ash to test its performance as opening agent and the last sub-study is on the properties of OSA monoliths obtained by accelerated carbonation, which draws on the recent developments in research of carbonate bonded construction materials [11,12,13]
Estonian oil shale ash (OSA) characterization results showed that the new types of OSA from
Summary
New initiatives by the European Commission aim at reducing air and water emissions and extensively encourage innovation in waste or residue recovery using “Best-Available Technologies”. Estonia is still mostly utilizing low calorific fuel—OS as a primary source of energy including electricity, heat and oil production across the country This heavy fossil fuel reliance produces abundant amounts of uncommon calcareous ash which has been deposited in landfills and waste piles over the years, since the ash lacks industrial applications [2,3]. The utilization of OSA in the production of new valuable products could be a partial solution for the Estonian OS sector by integrating core concepts from circular economy In this respect, OSA as any other industrial alkaline solid waste (such as lignite, coal, wood bottom and fly ashes (FAs), steel slags, cement production wastes and waste concrete), can be considered as a valuable raw material in the conventional production processes of cement, concrete and ceramics [8,9,10]. The current study includes three sub-studies of oil shale ash utilization in building materials; first sub-study is testing of self-cementing properties of all the currently generated OSAs, second sub-study is the clay brick production with oil shale ash to test its performance as opening agent and the last sub-study is on the properties of OSA monoliths obtained by accelerated carbonation, which draws on the recent developments in research of carbonate bonded construction materials [11,12,13]
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