Radiological and Leaching Assessment of Phosphogypsum and Fly Ash Mixtures

This experimental study is aimed to examine the radiological and leaching characteristics of raw phosphogypsum (PG), fly ash (FA), and compacted PG-FA mixes (40% PG and 60% FA, and 60% PG and 40% FA) for applications in road embankment and subgrade layer constructions. Radioactivity assessments were performed using gamma spectrometry and employing a high-purity germanium clover detector and RadEye personal radiation detector. Over a detection time of 43,200 s, gamma spectrometry received no significant contributions from radionuclides. Similarly, radiation data obtained from the RadEye personal radiation detector showed low radiation dose rates varying from 0.06 to 0.09 μSv/h, which were less than the ambient dose rate of 1 µSv/h and the annual effective dose of 1,000 µSv specified by the Atomic Energy Regulatory Board and the International Atomic Energy Agency. The results of the California waste extraction test indicated that the concentrations of various trace metals, except antimony, were within the threshold limits specified by the USEPA and European Commission criteria. Concentrations of trace metals such as As, Ba, Cu, Cd, Cr, Ni, Pb, Sb, and Zn ranged from 0.002 to 0.645 mg/L.