Effect of CO_(2)-mixing dose and prolonged mixing time on fresh and hardened properties of cement pastes  

作　　者：Minlu WANG Shuang LUO Ba Tung PHAM Tung-Chai LING 

机构地区：[1]College of Civil Engineering,Hunan University,Changsha 410082,China

出　　处：《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》2023年第10期886-897,共12页浙江大学学报（英文版）A辑（应用物理与工程）

基　　金：supported by the Science and Technology Innovation Plan of Hunan Province(No.2022WZ1010);the Program Fund of Non-Metallic Excellence and Innovation Center for Building Materials(No.2023Ph.D-6),China.

摘　　要：This study aims to investigate the influence of CO_(2)-mixing dose(mass fractions of 0.3%,0.6%,and 0.9%)and prolonged mixing time on the fresh and hardened properties of cement pastes.The CO_(2)-mixing can act as coagulant in fresh cement mixtures,resulting in a significant reduction in workability associated with the formation of a rich calcium carbonate network on the surface of cement particles.The CO_(2)-mixing cement pastes were found to be much stiffer and more difficult to handle,place,and compact than the control mixture,which had a negative effect on the mechanical strength performance of the hardened pastes.However,prolonging the mixing time for 1 min(immediately after CO_(2)-mixing)can effectively improve the workability(by~53%–85%)by breaking up the flocculation network of deposited calcium carbonates.As a result,the presence of detached calcium carbonate accelerated early cement hydration and densified the microstructure;this improved early-age compressive strength by~6%–32%,depending on the CO_(2)-mixing dose used.Therefore,it seems that the CO_(2)-mixing dose should be controlled at≤0.6%with the mixing time prolonged in order to attain satisfactory workability and mechanical strength.

关 键 词：CO_(2)-mixing Calcium carbonate Early cement hydration FLOWABILITY Microstructure 

分 类 号：TE377[石油与天然气工程—油气田开发工程]