Mechanical properties, durability, and life cycle assessment of recycled brick powder concrete reinforced with different fibers

The recycling of construction and demolition waste containing clay bricks inevitably yields waste clay brick powder as a by-product. By optimizing the particle size and replacement level of waste clay brick powder, a composite cementitious material with high mechanical strength and enhanced durability can be developed. In this study, recycled brick powder (RBP) of varying particle sizes was produced from discarded clay bricks. RBP was then used to replace cement at different substitution rates to produce recycled brick powder concrete (RBPC). Then, five types of fibers, including 12 mm long polypropylene fiber (PPF-12), 19 mm long polypropylene fiber (PPF-19), copper-coated steel fiber (CF), glass fiber (GF), and basalt fiber (BF), were added to RBPC to further enhance the performance of RBPC. The mechanical properties, durability tests, and life cycle assessment of the fiber-reinforced RBPC were also carried out. The results show that the optimal particle size and substitution rate of RBP are 0.075 mm and 5%, respectively. CF has the best effect on improving the mechanical properties of RBPC, while PPF-12 has a stronger impact on improving the mechanical properties of RBPC than PPF-19. Scanning electron microscopy analysis showed that CF and BF had the best binding effect with cement hydration products. In addition, the durability of RBPC was improved after adding fibers. Among them, BF had the best impact on improving the high temperature resistance and corrosion resistance of RBPC, and CF had the best effect on improving the freeze-thaw resistance of RBPC, followed by BF. Life cycle assessment shows that fiber-reinforced RBPC is more sustainable and economically friendly. Among them, RBPC doped with BF has the best sustainability, while RBPC doped with PPF-12 is the most economical.