Simulation of Radon Transport through Building Materials: Influence of the Water Content on Radon Exhalation Rate

Abstract

Radon transport in porous materials is strongly influenced by the presence of water. It is also necessary to be able to numerically control the effects of this parameter. The radon concentration and radon exhalation rate have been determined by simulation in various building materials containing an increasing water content. It has been proved that the presence of water does not involve the same variations in the concentration on the surface of the medium, according to its porosity. For porous media with low porosity like concrete or granite, ( < 0:2), the radon concentration and radon exhalation rate sharply increase with water until the volumetric water content becomes higher than 30%. At this point, radon emanation plays an important role, in relation to the molecular diffusion process. For materials with medium porosities (e.g., limestone, brick, cement: 0:3 < < 0:45), the concentration was observed to increase up to a volumetric water content of about 10% and then decreased from there. In this case, the molecular diffusion has a greater effect due to a greater quantity of pores in the material. For a small water content, this parameter tends to make the radon concentration decrease at the surface of the medium. These simulations have been compared with experimental analysis and are in strong accordance with the experimental results.

Radon diffusion and exhalation from mortar modified with fly ash: waste utilization and benefits in construction

“…The details of the continuous radon monitor described elsewhere [36]. The growth of radon concentration in a chamber of volume 'V' is given by [37].…”

Radon exhalation of hardening concrete: monitoring cement hydration and prediction of radon concentration in construction site

“…It is known that the radon emanation coefficient under saturated conditions is smaller than that under dry conditions, whatever the building material (Fournier et al, 2005). This behavior stems from the fact that the recoil distance of the radon atoms in air is about 900 times higher than in water.…”

“…At the same time, the presence of water in a porous medium is known to dramatically influence radon diffusion. For example, Fournier et al (2005) found recently that radon diffusion coefficient in cement decreases from w1 Â 10 ÿ2 (dry material) to w2 Â 10 ÿ6 m h ÿ1 (saturated material).…”

Des détecteurs de traces à la radiobiologie : la contribution du LMN-AC

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