From Cementitious Systems to Crushed Construction and Demolition Waste-Derived Geopolymers: Emerging Advanced Matrices for Radionuclide Immobilization

Abstract

Construction and demolition waste (C&DW) has been investigated both for radionuclide sorption and as a precursor for geopolymer materials. However, research on C&DW-derived geopolymers has primarily focused on synthesis and characterization, while their role in radionuclide immobilization remains insufficiently explored. This review evaluates C&DW-derived geopolymers as promising matrices for radionuclide immobilization, focusing on retention capabilities and factors influencing immobilization performance. Available studies indicate that waste-derived geopolymer systems can limit radionuclide mobility and leaching, but their performance strongly depends on precursor composition, phase assemblage, and matrix structure. The mineral complexity of C&DW-derived matrices may provide diverse retention pathways, supporting their consideration as immobilization materials. Linking the documented sorption capacity of C&DW materials with the immobilization potential and favorable characteristics of C&DW-derived geopolymer matrices represents a promising approach for developing advanced systems for radionuclide solidification. Due to the limited number of studies directly addressing radionuclide immobilization in C&DW-derived geopolymer systems, evidence from related studies is considered to support assessment of their immobilization capacity. Nevertheless, further clarification is required regarding the integration of existing research findings, precursor heterogeneity, multi-ion interactions, and long-term performance under realistic conditions. Addressing these limitations through systematic investigations is essential to support their application in radioactive waste (RW) management.