Thermal analysis testing and natural radioactivity characterization of kaolin as building material

Abstract

Kaolins are used in a multiplicity of industries because of unique physical and chemical properties. Relationships between thermal and radioactivity properties are discussed in its application as a building material. Super-fine kaolin powder with particle sizes about 30 mu m was analyzed. Simultaneous TGA/DTA analysis was performed on powder samples at various heating rates in an argon atmosphere. Based on investigated thermal properties, it was concluded that dehydroxylation process can vary depending on the characteristics of starting material. The maximum degree of the dehydroxylation (D (T)) was obtained at the lowest rate of heating (D (T) = 60.79% for 10 A degrees C min(-1)). With an increase in the heating rate, decline in D (T) value was observed. Based on comprehensive testing, it was identified that the degree of dehydroxylation does not drop below 50%. It was concluded that appointed experimental conditions seem sufficient admissible for obtaining degree of dehydroxylation (D (T)) higher than 50%. In order to safe use of kaolin as a building material from the standpoint of radiological safety, content of natural radionuclides was determined by gamma spectrometry.