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

Abstract

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 ²²⁶Ra and ²³²Th increased after sintering process from raw material to clinker, as a result of concentrating effect on ²²⁶Ra and ²³²Th during sintering process, but the specific activity of ⁴⁰K decreased after sintering process as a result of volatilization effect. Radionuclide ²²⁶Ra mainly distributed in RFC silicate phases (C _xS), ²³²Th distributed more in RFC interstitial phases than RFC silicate phases (C _xS), ⁴⁰K mainly distributed in RFC interstitial phases. With increasing hydration ages of RFC pastes, the specific activity of ²²⁶Ra kept increasing, ²³²Th remained consistency all the same and ⁴⁰K declined. The radioactivity of RFC was in the recommended safe limit of Chinese National Standards GB6566-2010 during its preparation and application process.

Keywords

red mud / distribution / radioactivity / specific activity / cement / hydration

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