Reduction of Radon Gas in Concrete Using Admixtures and Additives

Abstract

The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined three concrete recipes where only an additive as well as fly ash were added as single constituents to a reference recipe and compared to a reference concrete. The inputs of an additive as well as a supplementary cementitious material (fly ash) were made as a mean to investigate their potential influence on the radon exhalation rates of the concrete. Measurements were performed with an ATMOS 33 ionizing pulsation chamber for at least five different occasions for each recipe during a 22 month period. The results indicate a reduction of the exhalation rate by approximately 30-35 % for each altered recipe. This means roughly 1.5-2 mSv per year decrease in effective dose to a human using an additive or a supplementary cementitious material such as fly ash in relation to the investigated standard concrete.

Effect on Radon Exhalation Rate Due to Cracks in Concrete

“…Finally, it should be noted that the initial radon exhalation values measured for the exhalation rate of the concrete prisms in a pristine state, is lower for the recipe "ADD". This is as predicted [6], but a small change in these lower values have a large impact, when a percentage increase is calculated.…”

“…The compressive strength of the examined concrete cubes is in line with expectations or possibly better [10]). The results seem solid and a lower compressive strength for a recipe containing a hydrophobic additive is anticipated [6]. This is also, what could be observed from the results.…”

“…One, with only ordinary Portland cement (OPC-CEM I), abbreviated "REF" and one including a bulk additive (bulk additive/liquid additive) abbreviated "ADD". The cause for including an additive was due to earlier investigations [6] that had shown that an addition of a liquid additive with hydrophobic character could lower the exhalation rate.…”

Radon, Concrete, Buildings and Human Health—A Review Study

“…A 30-35% decrease in the radon gas exhalation rate of fly-ash-added concrete samples was observed with a relative humidity below 80-85% [211]. As a result of a study [210] presenting an updated database on the natural radioactivity in construction materials in Europe, an average radon exhalation rate of 17 Bqkg −1 h −1 was obtained for concrete.…”