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

Author(s): Run-Sheng Lin and Xiao-Yong Wang

Publication: Materials Journal

Volume: 120

Issue: 5

Appears on pages(s): 31-42

Keywords: calcined clay blended concrete; carbon dioxide (CO2) conversion; durability; nano-CaCO3; strength

DOI: 10.14359/51738889

Date: 9/1/2023

Abstract:
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, ultrasonic 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.