Preparation of green concrete from bamboo biochar (BB) and concrete slurry waste (CSW): Preparation method and performance evaluation

Concrete slurry waste (CSW) is a solid waste that poses serious potential threats to environmental safety due to its high alkalinity and landfill disposal. To efficiently recycle CSW, the potential hydration activity and concrete engineering properties of CSW were improved by adding bamboo biochar (BB). In the experiment, carbon negative concrete was prepared by synergistically replacing recycled fine aggregate with recycled fine aggregate using BB with particle sizes ranging from of 0.075–1.2 mm and substitution rates of 10 %, 20 %, and 30 % (by volume) in equal quantities. Moreover, the degree of CSW hydration, engineering properties of carbon negative concrete, and amount of carbon sequestration were quantitatively analyzed. The results indicated that BB increased the hydration degree of the CSW with an increase in dosage. When the BB dosage reached 30 %, the cumulative heat of hydration at 75 h of the mortar prepared based on CSW-3 increased by 26.2 %, and the degree of hydration of the silicate phase increased by 45.7 %, compared with the BB-0 group. In addition, The addition of BB not only improved the concrete engineering performance but also effectively realized carbon sequestration, which resulted in the preparation of sustainable carbon negative concrete with both environmental and engineering benefits.