Development of cementitious materials for successful radon immobilization

Abstract

The focus of this investigation is on the immobilisation of phosphogypsum (PG) into various cementitious materials. Secondary pollution by the presence of naturally occurring radionuclides (NOR) in PG must be avoided. Therefore, in addition to gamma radiation (regulated for building materials by the European Basic Safety Standards (EU-BSS)), the presence of radium (further on referring to 226Ra) as main radionuclide in PG requires particular evaluation of radon exhalation (further on referring to 222Rn). The radon immobilisation potential of five cementitious materials was assessed, i.e. alkali-activated binders, cement and hybrid cement. 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.