Roles of Biochar and CO 2 Curing in Sustainable Magnesia Cement-Based Composites

作者：Lei Wang, Liang Chen, Chi Sun Poon, Chi‐Hwa Wang, Yong Sik Ok, Viktor Mechtcherine, Daniel C.W. Tsang · 发表于：ACS Sustainable Chemistry & Engineering · 年份：2021 · 被引用次数：160 · 研究领域：Magnesium Oxide Properties and Applications、Concrete and Cement Materials Research、Layered Double Hydroxides Synthesis and Applications

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 CO 2 curing on the pastes. The thermogravimetric and X-ray diffraction analyses showed that the incorporation of biochar, especially CO 2 gasification biochar, promoted the generation of hydration products due to the internal curing effect. The use of CO 2 curing effectively accelerated the carbonation of pastes. Hydrated magnesium carbonates were preferentially formed in CO 2 -cured MC pastes, whereas CaCO 3 was preferentially generated in CO 2 -cured MP pastes. Moreover, the incorporation of biochar, especially porous CO 2 gasification biochar, could further facilitate CO 2 diffusion and promote carbonation. As a result, the synchronous use of biochar and CO 2 curing significantly enhanced the mechanical strength of blocks. Therefore, biochar-augmented and CO 2 -enhanced composites could be novel and low-carbon construction materials for sustainable engineering applications.