期刊
JOURNAL OF MATERIALS IN CIVIL ENGINEERING
卷 33, 期 4, 页码 -出版社
ASCE-AMER SOC CIVIL ENGINEERS
DOI: 10.1061/(ASCE)MT.1943-5533.0003652
关键词
Hydrated cement powder (HCP); CO2 treatment; Compressive strength; Calcite; Microstructure
资金
- National Natural Science Foundation of China [5181101350, 51950410584]
- Young Talent Program of the Hunan Provincial Government [801201048]
This study aimed to enhance the properties of residual hydrated cement powder (HCP) from recycled concrete via CO2 treatment. The study found that carbonation can effectively reduce the porosity of HCP by forming calcite, leading to higher compressive strength in concrete.
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.
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