Multi-faceted assessment of microbial-reinforced recycled brick aggregate concrete.

• The microbial was used to reinforce the RBA. • The microstructure of RBC was quantitatively characterized. • Mechanical properties and frost resistance of RBC were improved. • Microbial-reinforced RBC had good environmental and economic benefits. Improving the performance of recycled brick aggregates to enhance concrete performance is the key to promoting recycled concrete technology. In this paper, pure bacteria (Bacillus subtilis) and unoptimized activated sludge mixed bacteria are used to reinforce recycled brick aggregates by soaking them, and a multi-faceted assessment evaluation of microbial-reinforced recycled brick aggregate concrete is carried out. After microbial reinforcement treatment, the performance of recycled brick aggregates and recycled brick aggregate concrete improve. The water absorption and crushing index of recycled brick aggregates can be reduced by up to 20% and 8.1%, respectively; the compressive strength and tensile strength of recycled brick aggregate concrete can be increased by up to 16.7% and 11.7%, respectively. After 60 freeze−thaw cycles, the mass loss, compressive strength, and relative dynamic modulus loss of the microbial-reinforced recycled brick aggregate concrete decrease by 0.5%, 6.0%, and 12.0%, respectively, compared to those of the unreinforced recycled brick aggregate concrete. In addition, compared with those of unreinforced recycled brick aggregate concrete, the CO 2 emission-strength relationship index and material cost-strength relationship index of microbial-reinforced recycled brick aggregate concrete are reduced by 13.5% and 10.9%, respectively, indicating that it has good environmental and economic benefits. [ABSTRACT FROM AUTHOR]