Development of cementitious materials for successful radon immobilization

Abstract

In case phosphogypsum (PG) is being used in the production of cementitious materials, the presence of 226Ra as main radionuclide in PG requires particular evaluation of 222Rn exhalation. Ideally, cementitious materials are capable to immobilize 222Rn in their solid matrix, while the degree of immobilization is dependent on their porosity features and durability. Alkali-activated binders, cement and hybrid cement matrices are assessed. Alkali-activated binders were composed of ground granulated blast furnace slag (GGBFS) and PG, cement samples were a combination of Ordinary Portland Cement (OPC) and PG, while hybrid cement samples consisted of GGBFS, OPC and PG. Gamma spectroscopy was performed for the determination of the 226Ra activity concentration of the samples. 222Rn exhalation was measured after variable curing times. The total open porosity was estimated with a water absorption test after 4 weeks of curing.