Activity concentration and annual effective dose assessments of radon in SCCs with different mineral additives

Abstract

This study was conducted to investigate the hypothesis that radon gas emanation which is harmful to human health may occur more than standard values in Self-Compacting Concrete (SCC) which has a higher amount of dust material than conventional concretes. The SCCs with 5 %, 12.5 %, and 20 % fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBFS) as well as control concretes without mineral additives were placed closed glass environments with dimensions of 150×150×150 mm; average radon activity concentrations (ARACs) were measured passive method by CR-39 nuclear trace detectors after 7–14-21–28-56–90 and 120 days. Radioactivity analyses including annual effective equivalent dose (AEED) calculation of the concretes were also done. The ARAC values of SCCs increased significantly along with the increase of FA and decreased significantly with the increase of SF. So that the ARAC value (131.56 Bq/m3) of SCC with 20 % FA increased 2.40-fold when compared to the control concrete; however, the ARAC value (14.22 Bq/m3) of SCCs containing 20 % SF was found 4.5-fold lower than the control concrete. 5 % of the concretes containing GGBFS reduced the radon gas emanation; however, the rates of 12.5 % and 20 % increased the emanation. The highest AEEDs for each mineral additive type were 7-day samples including 20 % of FA (8.00 mSv/year), 5 % of GGBFS (3.17 mSv/year) and 5 % of SF (2.16 mSv/year). 12.5 % and 20 % FA-added SCCs emit radon gas above the limit levels. The results have confirmed the hypotheses of the present research depending on the mineral additive type and rate.