Radioactivity levels of limestone and gypsum used as ...
Sixtysix limestone samples and 38 gypsum samples were collected from different quarries as shown in Figure 1. The samples weighing from to 1 kg were catalogued, coded properly and ground into a fine powder with a particle size <1 mm. The samples were then dried in a temperaturecontrolled furnace at 110°C for 20–24 h to remove moisture.