Performance Optimization and Carbon Reduction Potential of Bamboo Biochar for Lightweight Artificial Aggregates

To realize the efficient utilization of biochar and construction solid waste in building materials production, a novel core-shell aggregate concept is proposed, in which artificial aggregates are prepared by encapsulating coarse-particle bamboo biochar (C-BB) with concrete slurry waste (CSW), calcium carbide slag (CCS), and fine-particle bamboo biochar (F-BB). The results showed that the best engineering properties of the artificial aggregates were achieved when the F-BB content was about 6%, with crushing strength, water absorption, and bulk density values of 4.7 MPa, 14.3%, and 796 kg/m³, respectively. In addition, the artificial aggregates have promising potential for CO₂ uptake under a CO₂ curing system and can achieve 5.72% (by mass) uptake when the F-BB content is 6%. This performance is attributed to the formation of well-developed CO₂ transport channels in the shell matrix by the F-BB particles. In summary, the novel core-shell aggregate not only has better engineering properties than commercial lightweight aggregates but also offers significant potential for CO₂ sequestration, opening new opportunities for the efficient application of biochar in construction materials with both engineering and environmental benefits.