Radon immobilization potential of alkali-activated materials containing ground granulated blast furnace slag and phosphogypsum

This study evaluates the immobilization potential of 222Rn in alkali-activated materials (AAMs) based on ground granulated blast furnace slag (GGBFS). As radon source, 10 wt% phosphogypsum (PG) was added to evaluate PG reuse via AAMs. Matrix properties were modified by varying alkali activator's SiO2/Na2O and H2O/Na2O ratios. During hardening of AAMs, radon release occurs in three stages resulting, after 30 h, to 0.26 Bq/(kg∗h). By varying the alkali-activator, massic exhalation for hardened samples decreased down to 0.01 Bq/(kg∗h). Radon release was successfully reduced mainly by physical encapsulation, with best results being achieved by adjusting the alkali-activator to SiO2/Na2O = 0.75 and H2O/Na2O = 20.