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Location
Lexington, Kentucky
Start Date
5-5-2026 1:30 PM
End Date
5-5-2026 2:00 PM
Description
This study investigates high volume of Ordinary Portland Cement (OPC) substitution with fly ash based calcium sulfoaluminate binder. The utilization of circulating fluidized bed combustion (CFBC) boilers imposes limitations on the recycling of fly ash due to its lower combustion temperature inhibiting the formation of reactive calcium silicate minerals resulting in diminished pozzolanic properties of the ash paste. Our previous research (Paaver et al., 2020, 2022) has demonstrated that the mechanical activation of sulfur and calcium-rich Estonian oil shale CFBC fly ash produces calcium sulfoaluminate (CSA) type active binder allowing high-volume OPC replacement of up to 50%, with a reduction in strength of less than 10%. Over the coming decades, the Estonian oil shale energy sector is planned to be closed and replaced with renewable energy production minimizing problems with combustion ash waste production. However, the oil shale industry will leave more than five hundred millions of tonnes of landfilled ash deposited over 70 years. The landfilled Ca-rich legacy ash has been considered as stabilized inert material due its hydration and carbonation. Nevertheless, we have earlier shown (Leben et al., 2019) that carbonation of the ash deposits is limited only to the surface layer of the more than 45 m high plateau-like ash deposit piles. This means the hydrated as can be thermally reactivated without invoking carbonate-bound CO2 emission. Our results show that hydrated legacy ash from hydrated ash sediment plateaus can be chemically reactivated at temperatures 100-400 °C and, combined with mechanical activation, can be used to produce similar to fresh CFBC ash the CSA type binder for potential use as a partial substitute for Portland cement and/or as a composite binder for lightweight blocks.
Document Type
Presentation
Archival?
Archival
Included in
Energy Systems Commons, Environmental Indicators and Impact Assessment Commons, Environmental Monitoring Commons, Mining Engineering Commons, Oil, Gas, and Energy Commons, Structural Materials Commons, Sustainability Commons
Thermal and Mechanical Activation of Estonian Oil Shale CFBC and Hydrated Legacy Fly Ash as an Alternative Binder System for OPC Replacement
Lexington, Kentucky
This study investigates high volume of Ordinary Portland Cement (OPC) substitution with fly ash based calcium sulfoaluminate binder. The utilization of circulating fluidized bed combustion (CFBC) boilers imposes limitations on the recycling of fly ash due to its lower combustion temperature inhibiting the formation of reactive calcium silicate minerals resulting in diminished pozzolanic properties of the ash paste. Our previous research (Paaver et al., 2020, 2022) has demonstrated that the mechanical activation of sulfur and calcium-rich Estonian oil shale CFBC fly ash produces calcium sulfoaluminate (CSA) type active binder allowing high-volume OPC replacement of up to 50%, with a reduction in strength of less than 10%. Over the coming decades, the Estonian oil shale energy sector is planned to be closed and replaced with renewable energy production minimizing problems with combustion ash waste production. However, the oil shale industry will leave more than five hundred millions of tonnes of landfilled ash deposited over 70 years. The landfilled Ca-rich legacy ash has been considered as stabilized inert material due its hydration and carbonation. Nevertheless, we have earlier shown (Leben et al., 2019) that carbonation of the ash deposits is limited only to the surface layer of the more than 45 m high plateau-like ash deposit piles. This means the hydrated as can be thermally reactivated without invoking carbonate-bound CO2 emission. Our results show that hydrated legacy ash from hydrated ash sediment plateaus can be chemically reactivated at temperatures 100-400 °C and, combined with mechanical activation, can be used to produce similar to fresh CFBC ash the CSA type binder for potential use as a partial substitute for Portland cement and/or as a composite binder for lightweight blocks.
