Upcycling recycled cement paste into high-performance SCMs via TEA-enhanced wet carbonation

The low reactivity of recycled cement paste (RCP) limits its value as a supplementary cementitious material (SCM). This study presents a rapid and efficient method to overcome this barrier by employing triethanolamine (TEA) as an activator for the wet carbonation of RCP. The results demonstrate that TEA enhances the CO 2 uptake rate by 12.4% within a mere 10 min reaction. While the carbonation product remains primarily calcite, the incorporation of the TEA-activated RCP significantly accelerates the early hydration of cement mortar and leads to a notable improvement in compressive strength. These findings reveal that TEA not only promotes carbonation efficiency but also functionally modifies the RCP, endowing it with superior pozzolanic properties. This work provides a novel and practical strategy for upcycling construction waste into high-value, performance-enhancing SCMs.