Accelerated carbonation of recycled concrete aggregate in semi-wet environments: A promising technique for CO2 utilization

Yining Gao, Yi Jiang, Yong Tao, Peiliang Shen, Chi Sun Poon

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)


The practical implementation of accelerated carbonation for recycled waste concrete is impeded by sluggish carbonation efficiency. In contrast to previous carbonation enhancement schemes using high-pressure gas and/or complex pre-/post-processing, this study introduces a novel semi-wet carbonation method that achieves high-efficiency carbonation of recycled concrete aggregates (RCA) in a practically simple way. A noteworthy carbonation degree of 10.6 % was achieved within 30 min at room temperature and ambient pressure, which enhanced the RCA by reducing the water absorption rate and porosity by 3.6 % and 20 % respectively. The formed CaCO3 is primarily in calcite form with poorer crystallinity and smaller grain size and the formed silica gel features a lower polymerization degree compared with those formed in wet carbonation. It is due to that the carbonation reactions for the semi-wet scenario happen at the spatially confined water film of the solid-liquid interface. Moreover, the addition of sodium bicarbonate significantly accelerated the semi-wet carbonation, which is due to the weak alkaline environment lowering the CO2 speciation free energy as revealed by reactive molecular dynamics simulations. The proposed semi-wet carbonation method provides a promising way of pushing industrial CO2 capture and utilization.

Original languageEnglish
Article number107486
JournalCement and Concrete Research
Publication statusPublished - Jun 2024


  • CO capture and utilization
  • Recycle concrete aggregate
  • Semi-wet carbonation

ASJC Scopus subject areas

  • Building and Construction
  • General Materials Science


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