Performance Evaluation of Eco-Friendly Recycled Powder in Foamed Concrete: Influence of Powder Types and Replacement Ratios

The preparation of construction waste into eco-friendly recycled powder (RP), partially replacing cement to produce foam concrete with thermal insulation properties, provides a new approach for the resource utilization of RP. In this study, different components of construction waste were used to prepare recycled paste powder (RPP), recycled brick powder (RBP), and recycled concrete powder (RCP). The effects of RP on the microstructural and macroscopic properties of foam concrete were investigated at replacement rates ranging from 0% to 30%. The research results indicate that the microstructure of all three types of RP exhibits irregular shapes, and their chemical compositions show significant differences. Partial replacement of cement with these RP leads to the deterioration of the matrix microstructure, which negatively affects the workability and mechanical properties of the foam concrete. However, the addition of RP effectively mitigates the drying shrinkage of the foam concrete, with RBP showing particularly outstanding performance in this regard. Specifically, the maximum drying shrinkage rate of F-30RBP is 9.33% and 11.31% lower than that of F-30RPP and F-30RCP, respectively. Furthermore, the incorporation of RP has a minimal effect on the thermal conductivity of the foam concrete, indicating that RP is well-suited for use in foam concrete.