Effect of accelerated carbonation on the efficiency of immobilization of Cs in the alkaliactivated blast furnace slag

Abstract

In this paper the effect of accelerated carbonation process on the effectiveness of immobilization of cesium (simulated radioactive and toxic waste) in the alkali-activated blast furnace slag (AABFS) matrix was studied. Blast furnace slag (BFS) was contaminated with 2% and 5% Cs (with respect to the dry BFS mass) and alkali-activated with sodium silicate solution, while the AABFS samples were cured sealed in plastic envelopes for 24 h at 95oC. First series of AABFS samples were exposed to accelerated carbonation (open curing), while the second (reference) series of AABFS samples left to aging (also sealed) at room temperature until testing. Thereafter AABFS samples were subjected to a short-term (five-day) leaching tests according to the ANSI/ANS-16.1-2003 standard. The strength of AABFS mortars were tested according to the SRPS EN 196-1 standard, while the carbonation was confirmed by phenolphthalein test and SEM analysis. The diffusion coefficient (D) and non-dimensional leachability index (L) of cesium leached from AABFS were calculated according to the ANSI/ANS-16.1–2003 standard. A correlation between the accelerated carbonation process and the effectiveness of immobilization of cesium in AABFS was established.