Insights on solid CO2 mixing method for hybrid alkaline cement (HAC): performance, sustainability, and experimental system improvement

초록

New low-carbon concrete materials and technologies are urgently needed to reduce CO2 emissions and achieve sustainable development in the cement industry. Hybrid alkaline cement (HAC) is a new cement-based material that combines the advantages of ordinary Portland cement and alkali-activated cement. This study introduces a solid CO2 mixing method and investigated its impact on the performance and sustainability of HAC. Research results show that the initial internal temperature of HAC decreases after solid CO2 is mixed. The temperature gradually increased and surpassed that of the control sample within 12 h. The sequestration of solid CO2 triggers a carbonation reaction within the material, leading to a reduction in calcium hydroxide and an increase in calcium carbonate content. An increase in solid CO2 leads to a decrease in workability. Tests lasting up to 90 days demonstrated that the method substantially enhanced the strength and resistivity of HAC. This study considers two boundary conditions due to CO2 escape when quantifying the CO2 emissions of HAC and clarifies the specific levels under actual dose and optimized dose scenarios. The findings demonstrate the potential of the solid CO2 mixing method to optimize material performance while highlighting its dual impact on sustainability. In addition, this study proposes an experimental idea for recovering the escaped CO2 and using it for carbonation curing. These findings provide valuable insights and practical foundations for advancing the concrete industry to achieve sustainable development.

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