Study of porous layers for the stablishment of design parameters applied to depressurization techniques for radon mitigation

Radon gas is a naturally occurred radioactive gas, that is considered among the most usual pollutants in buildings. Its presence poses a health hazard for occupants, being classified by the World Health Organization as carcinogen and as one of the major causes of lung cancer. Radon is produced mainly from the radioactive decay of radio (soils with uranium content), which is naturally found in soils. Radon enters buildings through floor and building envelope, and may accumulate indoor, increasing concentration till significant risk levels. There are several strategies that can be used to reduce inner radon levels, being the soil depressurization one of the most effective. The depressurization technique generates a negative pressure field under the building. The pressure gradient attracts soil gas toward the outside, avoiding the gas entry to inner building spaces. Radon Flow Project (2020-2023) is funded by Spanish Ministry of Science and Innovation. The aim of this project is to improve depressurization technique by including porous materials as floor components. With a suited design based in permeability, air resistance, and porosity, the porous surface may aid to attract, transport, and evacuate the subsoil air, reducing indoor radon concentrations to safe levels. The project pretends to contribute with the objectives of the European Directive 2013/59/23/Euratom about protection against ionizing radiation. Gas transport physics in porous media is studied in the first part of the project. The study is carried out over a simulation model consisting in a real scale concrete slab built over different granular substrates. The slab is monitored with a net of differential pressure sensors, which provide real time information about pressure state at porous media. By actuating a suction system, different pressure fields and its development according to substrate permeability and porosity, are studied. This first step sets the framework for the definition of the new materials design criteria. This work reports field studies over the real simulation model, showing the range and morphology of pressure field due to different substrates and suction system characteristicsThis research was funded by the Spanish National Research Council (CSIC), project RADON_FLOW [PID2019-109898RB-I00], an entity under the aegis of the country's Ministry of Science and Research. The study was conducted at the Eduardo Torroja Institute for Construction Science (IETcc), Spain