Study of radon transport through concrete modified with silica fume

• Radon diffusion study through silica fume modified concrete was carried out.
• Radon diffusion coefficient of concrete decreased with increase of silica fume contents.
• Compressive strength increased with increase of silica fume.
• Radon exhalation rates and porosity of samples decreased with addition of silica fume.
• Radon diffusion coefficient decreased to 2.6% by 30% silica fume substitution.

The concentration of radon in soil usually varies between a few kBq/m3 and tens or hundreds of kBq/m3 depending upon the geographical region. This causes the transport of radon from the soil to indoor environments by diffusion and advection through the pore space of concrete. To reduce indoor radon levels, the use of concrete with low porosity and a low radon diffusion coefficient is recommended. A method of reducing the radon diffusion coefficient through concrete and hence the indoor radon concentration by using silica fume to replace an optimum level of cement was studied. The diffusion coefficient of the concrete was reduced from (1.63 ± 0.3) × 10−7 to (0.65 ± 0.01) × 10−8 m2/s using 30% substitution of cement with silica fume. The compressive strength of the concrete increased as the silica-fume content increased, while radon exhalation rate and porosity of the concrete decreased. This study suggests a cost-effective method of reducing indoor radon levels.