Radioactive Element Distribution Characteristics of Red Mud based Field Road Cement before and after Hydration

Red mud was firstly used as a raw material in sintering field road cement. Then, the radioactive element distribution characteristics of red mud based field road cement (RFC) before and after hydration were comparatively investigated. The experimental results indicated that the specific activity of 226 Ra and 232 Th increased after sintering process from raw material to clinker, as a result of concentrating effect on 226 Ra and 232 Th during sintering process, but the specific activity of 40 K decreased after sintering process as a result of volatilization effect. Radionuclide 226 Ra mainly distributed in RFC silicate phases (C x S), 232 Th distributed more in RFC interstitial phases than RFC silicate phases (C x S), 40 K mainly distributed in RFC interstitial phases. With increasing hydration ages of RFC pastes, the specific activity of 226 Ra kept increasing, 232 Th remained consistency all the same and 40 K declined. The radioactivity of RFC was in the recommended safe limit of Chinese National Standards GB6566-2010 during its preparation and application process.