Performance of CCX-B® Concrete Filled Geosynthetic in Reducing Radon Gas Emissions from Thawing Permafrost

ABSTRACT: As permafrost thaws, it can release radon gas, particularly in uranium-rich regions like northern Canada, posing environmental and health risks. The geology of these areas—rich in U-238—amplifies exposure concerns for nearby communities. Current radon-related provisions in the 2010 Canada Building Code have not significantly reduced indoor exposure, prompting the need for improved mitigation strategies. This study evaluates the performance of a CCX-B® concrete-filled geosynthetic layer as a soil gas barrier in cold regions. A Thermo-Hydro-Chemical finite element model simulates radon transport under freeze-thaw conditions, accounting for construction materials and foundation systems. A parametric study examines the influence of wall and slab thickness, insulation types, gas barriers, energy use, and climate extremes. Results show CCX-B® can reduce radon infiltration by 36-50% annually compared to natural soils. These findings highlight the potential of engineered barriers to protect northern communities and suggest integrating such systems into building codes for enhanced radon mitigation.