The effect of Cs and Sr on the mechanical properties of blast furnace slag inorganic polymer for radioactive waste immobilisation

Abstract

In pursuit of a sustainable society, researchers and industries have been increasingly studying the conversion of industrial residues into valuable construction materials such as inorganic polymers (IPs). These IPs can often be developed from both a single residue stream (e.g. metallurgical residue) or a combination of residue streams (typically amorphous/non-crystalline), mixed with an activating solution (e.g. Na-, K-hydroxides and silicates). The superior properties of IPs over OPC-based structures (fire resistance, chemical resistance, etc.) have led to different studies for their application as an immobilisation matrix for hazardous and radioactive substances. The effectiveness in immobilising elements such as cesium (Cs) and strontium (Sr) has been proven in several studies. However, the effect of the introduced elements on the properties of the IP-matrix has been studied to a much lesser extent. Also, due to high variability in precursor compositions and the differences between high-Ca and low-Ca IP strength development, the conclusions of these studies cannot easily be generalized. This study focusses on the effect of Cs+ and Sr2+ on the setting time, strength development, and microstructure of IPs developed from ground granulated blast-furnace slag (GGBFS).