A study of 226Ra concentration and radon exhalation rates in different geopolymer cement samples using CR-39 solid state nuclear track detector

Abstract

Radon is a naturally occurring radioactive gas that is known to cause lung cancer. Therefore, it is essential to measure and determine the concentration of radon in different materials. The purpose of this research is to measure and analyze the levels of radon concentration, radium concentration, and radon exhalation rates in various geopolymer cement mixes. These mixes are made from slag or metakaolin blended with different ratios of fly ash, silica fume, and cement kiln dust. The main goal is to determine the potential risks associated with using geopolymer cement materials in construction and how they may impact indoor air quality. To achieve this, the study will monitor the amounts of radon released from different geopolymer cement mixes and compare them to traditional cement samples. A CR-39 solid-state nuclear track detector will be used for monitoring purposes. Results of this study have revealed that the radon concentration varies from 4.03 to 348.21 Bqm−3 with an average value 62.01 Bqm−3. Radium concentration also changes from 15.18 to 926.47 Bqkg−1 with an average value 174.23 Bqkg−1. The value of the dissolved radon concentration in the collected samples alters from 4.57 to 394.87 Bqm−3 with an average value 70.32 Bqm−3. The mass exhalation rates are found to vary from 0.04 to 2.28 Bqkg−1h−1 with an average value 0.43 Bqkg−1h−1, while the surface exhalation rates vary from 0.91 to 78.92 Bqm−2h−1 with an average value 14.06 Bqm−2h−1. The Annual Effective Dose (AED), due to conducting the experiment indoors, has varied from 0.102 to 8.785 mSvy−1 with an average value 1.564 mSvy−1, where AED in the outdoor experiment has varied from 0.038 to 3.294 mSvy−1 with an average value 0.587 mSvy−1. According to the results, the geopolymer mixes labeled as (S) and (SS) containing 100% GGBFS and 85% GGBFS with 15% SF respectively has had the highest levels of radium concentration, radon concentration, dissolved radon concentration, radon exhalation rates, and AED. The investigation results indicate that, with the exception of samples (S) and (SS), the analyzed samples fall within the suggested range of acceptable values. Based on our results, it seems that all geopolymer samples except for (S) and (SS) are safe for being used in building materials production. We recommend utilizing these samples (S, SS) for public highways, bridges, and other buildings that have good ventilation.