CO2 treatment of hydrated cement powder: Characterization and application consideration
Document Type
Article
Publication Date
4-1-2021
Abstract
Residual hydrated cement powder (HCP) produced from recovering recycled concrete is usually restricted from being directly reused in concrete due to its high water absorption and porous structure. This study aims to enhance the properties of HCP via CO2 treatment. The simultaneous impacts of CO2 treatment and water-to-cement (w/c) ratio on physical properties and microstructure of HCP were studied. The findings showed that carbonation can effectively reduce the porosity of HCP owing to the formation of calcite, and the calcite content increases with increasing w/c ratio. Furthermore, there was a reduction in the 28-day compressive strength of paste specimens containing uncarbonated HCP, while paste containing 5%-20% of carbonated HCP (CHCP) achieved higher strength than the control paste. It is believed that the presence of calcite in CHCP leads to the formation of more stable calcium aluminate monocarbonate. The mass ratio of highly crystalline to poorly crystalline CaCO3 increased with an increase in the replacement level of CHCP, and the w/c ratio exhibited no significant influence at a given replacement ratio. (c) 2021 American Society of Civil Engineers.
Keywords
Hydrated cement powder (HCP), CO2 treatment, Compressive strength, Calcite, Microstructure
Divisions
fac_eng
Funders
National Natural Science Foundation of China (NSFC) (5181101350) (51950410584),Young Talent Program of the Hunan Provincial Government (801201048)
Publication Title
Journal of Materials in Civil Engineering
Volume
33
Issue
4
Publisher
ASCE-Amer Soc Civil Engineers
Publisher Location
1801 ALEXANDER BELL DR, RESTON, VA 20191-4400 USA