Optimization of monazite content in mortar cement and assessment of radiological risk in building materials

Abstract

Monazite contains natural radionuclides belonging to the natural radioactive series of uranium and thorium. The aim of the present investigation is to determine whether variations in monazite content can cause variations in naturally occurring radioactive material in ordinary Portland cement. Include a study on the feasibility of monazite as a building material. For this research, six cement–monazite mixtures were experimentally tested for radiological content with an HPGe gamma spectrometer. Radium equivalent, hazard indices, gamma index, and annual effective dose were all calculated from the measured gamma-ray spectra. With the samples' radium equivalents ranged from 33.51 Bq kg−1 to 796.81 Bq kg−1. The external and internal hazard indices varied from 0.57 to 0.91 Bq kg−1 and 0.64–1.13 Bq kg−1, respectively. The gamma index exceeded unity for samples with monazite concentration less than or equal to 0.016 % by mass when mixed and sand in mortar cement. The external and internal hazard indices varied from 0.57 to 0.91 Bq kg−1 and 0.64–1.13 Bq kg−1, respectively. The gamma index exceeded unity for samples with monazite concentration less than or equal to 0.016 % by mass when mixed and sand in mortar cement. The average annual effective dose rate from different cement–monazite mixtures varied from 19.35 to 441.41 mSv y−1 for cement and C-1-C-6 samples. The study demonstrated that as the concentration of monazite increased in the cement, the concentration of uranium, thorium series and 40K also increased for all practical purposes. As a result, monazite may only be utilized as a performance enhancer and not as a complete replacement or mixed for sand.

Keywords

• Monazite
• Natural radionuclides
• Building materials
• Radiation hazards
• Portland cement