Carbon footprint assessment and rheological properties of sodium abietate modified alkali-activated gangue backfill slurry

Abstract

Alkali-activated gangue-based backfill slurry (AGBS) can be used for CO₂ storage, but the rheological properties of AGBS are weakened after mineralizing and storing CO₂. Sodium abietate (SA) can act as a CO₂ air-entraining agent to optimize the rheological properties and CO₂ storage of AGBS. In this study, the impact of SA dosage on the rheological properties and CO₂ storage capacity of AGBS was explored. The results show that the incorporation of SA into AGBS leads to the formation of a substantial number of bubbles. These bubbles can be used to sequester CO₂ and provide nucleation sites for the generation of calcium carbonate, thereby reducing the viscosity and enhancing the ball lubrication effects. Consequently, the addition of SA significantly improves both the CO₂ storage capacity and rheological properties of AGBS. The results also indicate that the optimal SA dosage for AGBS is 0.4%. At this concentration, the CO₂ storage capacity of AGBS peaks at 1.97%, while the yield stress, plastic viscosity, and hysteresis loop area are minimized. However, an excessive amount of SA can lead to bubble collapse and fusion, thereby reducing the specific surface area and pore volume of AGBS. As a result, both the CO₂ storage capacity and the rheological properties of AGBS decrease. The results of the carbon footprint analysis show that the incorporation of SA can significantly reduce the carbon emissions from the transportation and production of AGBS and achieve the carbon emission reduction target.