Roles of Biochar and CO2Curing in Sustainable Magnesia Cement-Based Composites

Lei Wang, Liang Chen, C. S. Poon, Chi Hwa Wang, Yong Sik Ok, Viktor Mechtcherine, Daniel C.W. Tsang

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)


Biochar is a known product to permanently remove carbon from its cycle. It is essential to find high-quality and large-quantity utilization for biochar. This study assessed the efficacy of biochar on the hydration of magnesia cement (MC) and magnesia cement-Portland binary cement (MP)-based pastes and evaluated the synergistic effect of biochar and CO2 curing on the pastes. The thermogravimetric and X-ray diffraction analyses showed that the incorporation of biochar, especially CO2 gasification biochar, promoted the generation of hydration products due to the internal curing effect. The use of CO2 curing effectively accelerated the carbonation of pastes. Hydrated magnesium carbonates were preferentially formed in CO2-cured MC pastes, whereas CaCO3 was preferentially generated in CO2-cured MP pastes. Moreover, the incorporation of biochar, especially porous CO2 gasification biochar, could further facilitate CO2 diffusion and promote carbonation. As a result, the synchronous use of biochar and CO2 curing significantly enhanced the mechanical strength of blocks. Therefore, biochar-augmented and CO2-enhanced composites could be novel and low-carbon construction materials for sustainable engineering applications.

Original languageEnglish
JournalACS Sustainable Chemistry and Engineering
Publication statusPublished - 2021

Bibliographical note

Funding Information:
The authors appreciate the financial support from the Hong Kong Research Grants Council (PolyU 15222020) and the Alexander von Humboldt Foundation (AvH) for this study.

Publisher Copyright:


  • Accelerated carbonation
  • Biomass recycling
  • COgasification biochar
  • Carbon neutral
  • Sustainable construction materials

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Renewable Energy, Sustainability and the Environment


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