Carbon Dioxide Conversion and Use as Admixture for Calcined Clay Blended Pastes

초록

This study proposed using carbon dioxide (CO2) as an indirect admixture for calcined clay blended pastes. By injecting CO2 gas into limewater, solid nano-CaCO3 particles were synthesized and used to partially replace the binder at ratios of 2, 4, and 6%. Various tests and analyses were performed on the calcined clay blended pastes. After adding nano-CaCO3, the strength, ultra-sonic pulse velocity, hydration heat, and electrical resistivity were improved; monocarboaluminate and hemicarboaluminate were formed; and CO2 emissions were lowered. The electrical resistivity was improved more significantly than the strength. The reduction ratio in CO2 emissions was higher than the replacement ratio of nano-CaCO3. In summary, based on the transformation of gaseous CO2 to solid nano-CaCO3 particles, the proposed technique shows a similar concept to limestone calcined clay cement (LC3) concrete and can overcome the limitations of carbonation curing.

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