Biochar as green additives in cement-based composites with carbon dioxide curing

Lei Wang, Liang Chen, Daniel C.W. Tsang, Binglin Guo, Jian Yang, Zhengtao Shen, Deyi Hou, Yong Sik Ok, Chi Sun Poon

Research output: Contribution to journalArticlepeer-review

185 Citations (Scopus)


Biochar is a green material obtained from the thermochemical conversion of waste biomass under an oxygen-limited condition. This study demonstrated a novel and sustainable method for incorporating waste wood-derived biochar in cement-based composites with CO2 curing. The X-ray diffraction (XRD) and thermogravimetric analyses (TGA) illustrated that the incorporation of biochar promoted the generation of additional cement hydrates owing to moisture regulation effect, but did not accelerate or delay the hydration process as indicated by the isothermal calorimetry results. Specifically, the addition of 1 wt% biochar increased the compressive strength of composites by 8.9%. However, the incorporation of 5 wt% biochar reduced the compressive strength due to the porous and brittle structure of biochar. CO2 curing was employed to mitigate these adverse effects. The CO2 curing approach accelerated carbonation more effectively than the method of air curing for composites production. After carbonation, the abundant cement hydrates improved the bonding strength and the carbonates densified the microstructure, which substantially enhanced the mechanical strength and carbon sequestration. Therefore, the combined use of waste biochar and CO2 curing could be a green technology for enhancing properties of cement-based composites and promoting waste recycling and CO2 utilisation.

Original languageEnglish
Article number120678
JournalJournal of Cleaner Production
Publication statusPublished - 2020 Jun 10

Bibliographical note

Publisher Copyright:
© 2020 Elsevier Ltd


  • Accelerated carbonation
  • Biomass recycling
  • CO utilisation
  • Cement and concrete composites
  • Sustainable waste management
  • Wood biochar

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Environmental Science
  • Strategy and Management
  • Industrial and Manufacturing Engineering


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