Radiological and leaching assessment of an ettringite-based mortar from ladle slag and phosphogypsum

Abstract

In this investigation, ettringite-based mortars were synthesized from ladle slag (LS) and phosphogypsum (PG), promoting the concept of a circular economy. However, the reuse of naturally occurring radioactive materials (NORM), such as PG, requires radiological investigation. Also, the immobilization degree for contaminants contained in PG should be evaluated. The former was investigated using gamma spectroscopy and radon ex-halation/emanation tests, while the latter was assessed using an up-flow percolation column test according to the CEN/TS 16637-3. The produced mortars comply with current legislation on naturally occurring radio-nuclides (NOR) in building materials, proving that they can be safely used for building purposes. The radon emanation decreased upon increasing the Polish PG content, which was mainly determined by the micro-porosity. The specific surface areas were 20-30 times lower than conventional cement, and the immobilization degree for contaminants was generally high (> 90%). This investigation demonstrates high potential for PG reuse in ettringite-based mortars.