TY - JOUR
T1 - Biochar as green additives in cement-based composites with carbon dioxide curing
AU - Wang, Lei
AU - Chen, Liang
AU - Tsang, Daniel C.W.
AU - Guo, Binglin
AU - Yang, Jian
AU - Shen, Zhengtao
AU - Hou, Deyi
AU - Ok, Yong Sik
AU - Poon, Chi Sun
N1 - Funding Information:
The authors appreciate the financial support of the Hong Kong Research Grants Council ( PolyU 15223517 ) and the Alexander von Humboldt Foundation (AvH) for this study.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/6/10
Y1 - 2020/6/10
N2 - 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.
AB - 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.
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U2 - 10.1016/j.jclepro.2020.120678
DO - 10.1016/j.jclepro.2020.120678
M3 - Article
AN - SCOPUS:85079838832
SN - 0959-6526
VL - 258
JO - Journal of Cleaner Production
JF - Journal of Cleaner Production
M1 - 120678
ER -
