Interaction of carbonated recycled concrete powder with calcium sulfoaluminate-belite cement: Early hydration kinetics and microstructure evolution
Sijia Liu, Ken Yang, Linglin Xu, Zhenhua Duan, Jianzhuang Xiao, Zhenghong Yang
Abstract
This study aims to explore the value-added utilization potential of carbonated recycled concrete powder (CRCP) and calcium sulfoaluminate-belite (CSAB) cement in decarbonization and sustainable waste management strategies. Specifically, the interaction between CRCP and CSAB cement regarding the hydration kinetics and microstructure evolution were investigated. Results reveal that the incorporation of CRCP delays the initial hydration of ye'elimite, while enhancing the overall hydration degree of CSAB cement paste. A high dosage of CRCP (20 %) promotes the conversion of monosulfate to monocarbonate and hemicarbonate by providing more dissolved carbonate ions, demonstrating a stronger ability to stabilize ettringite; however, the dilution effect induces the decrease in strength. From the view of the CSAB cement, its elevated aluminate content and relatively low alkaline pH enhance the aluminate phase reaction with CRCP. Based on the coupling evaluation of carbon emissions and strength development, an optimum CRCP dosage of 10 % is proposed, achieving a CO 2 emission reduction of up to 43.6 % than Portland cement.