Use of carbonated recycled cement paste powder as a new supplementary cementitious material: A critical review

This paper focused on reviewing and decoupling analysis the effects of carbonated recycled cement paste powder (RCPP) as a new supplementary cementitious material (SCM) on the mechanical properties, rheology, durability, and carbon sequestration capacity of cement-based materials according to the results in previous studies. The results suggest that that carbonated RCPP serves as an excellent SCM in enhancing the compressive strength of cement paste, mainly through increasing the filler effect and the chemical reaction of CaCO3 with C(3)A. Extensive cement replacement with carbonated RCPP does not significantly reduce strength. However, when considering rheology and durability, particularly concerning steel corrosion, a 20-30 % cement replacement results in significant performance degradation due to the water absorption and the pozzolanic effect of silica gel, respectively. Furthermore, an increase in the carbonation products content (carbonation degree) can enhance the strength, but adversely affect rheological properties and corrosion resistance of reinforcement of cement-based material. Addressing this contradiction to synergistically enhance the various properties of cement-based material containing carbonated RCPP is the focus of future efforts.