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BULLETIN OF THE CHINESE CERAMIC SOCIETY ›› 2024, Vol. 43 ›› Issue (5): 1889-1896.

Special Issue: 资源综合利用

• Solid Waste and Eco-Materials • Previous Articles     Next Articles

Effect of CO2-Mineralized High-Calcium Fly Ash on Mechanical Properties and Micro-Structure of Cement Mortar

HUANG Huanghuang1,2, CHEN Tiefeng3,4, GAO Xiaojian3,4   

  1. 1. Hubei Longzhong Laboratory, Xiangyang 441000, China;
    2. School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China;
    3. School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China;
    4. Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, Harbin Institute of Technology, Harbin 150090, China
  • Received:2023-10-25 Revised:2023-12-21 Online:2024-05-15 Published:2024-06-06

Abstract: To improve the volume stability and hydration activity of high-calcium fly ash (HFA), CO2 mineralization treatment was applied in this paper. The CO2 uptake percentage and free CaO content of HFA undergone different CO2 mineralization duration were experimentally determined. The influence of CO2-mineralized HFA on hydration heat, mechanical properties and pore structure of cement mortar was investigated. The results show that after 12 h of CO2 mineralization modification treatment, the carbon sequestration of high calcium fly ash exceeds 10% (mass fraction), and the content of free calcium oxide in high calcium fly ash is significantly reduced. As the prolongation of CO2mineralization, the hydration induction period of cement slurry mixed with HFA is shortened, and the early hydration heat release is significantly reduced. CO2 mineralization can also mitigate the adverse impacts of HFA on mechanical strength, as well as improving the pore structure of cement mortar by reducing porosity and volume fraction of large capillary pores. Besides, CO2-mineralized HFA provides more nucleation sites for precipitation of C-S-H, accelerating the early hydration reaction of cement paste.

Key words: high-calcium fly ash, CO2 mineralization, mechanical property, pore structure, free CaO, cement mortar

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