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DIFFERENT STUDIES ON BUILDING MATERIALS

M.C. Faísca and M.M.R. Teixeira
ITN/DPRSN - Estrada Nacional nº10 - Apartado 21, 2686-953 Sacavém-Portugal
telephone: 00351 19550021- Fax:00 351 1 9941995 - e-mail: mcfaisca @ itn1.itn.pt

Several kinds of studies have been carried out concerning building materials.
The granitic region can be considered as a significant part of the country. In recent years granitic
materials are being used as ornements or integrated on the walls inside the houses, producing high
indoor radon levels. Studies of different coverings for granitic materials were tested employing incolor
paintings in order to reduce the radon exhalation from such granitic stones, without modifying their
appearance.
To obtain low indoor radon levels in new dwellings situated in radon prone areas, a selection of
building materials was carried out, consisting in an evaluation of natural radioactivity, namely 226 Ra, 232 Th, 40 K, as well as radon exhalation from building materials usually employed in construction.
Analyses of the correlation between 226 Ra content and radon exhalation from those materials were also
performed.
Due to the fact that, in general, the main indoor radon source is from the soil beneath the house,
experimental studies were carried out with different types of materials which might be employed as a
membrane and act as radon barrier. A selection of such materials was also performed accordingly their
effectiveness.
Besides, in Portugal there are several tonnes of phosphogypsum material and some attempts were done
in order to incorporate this kind of waste in building materials, mainly as a substitute of natural
gypsum. Studies were carried out, using phosphogypsum mixtures having different percentages of an
inert material. These experiments had the aim to reduce the radon exhalation and to provide a mixture
that can be used as a plaster on walls.
The aim of this paper is, therefore, to present the results of all these different studies which can
contribute to a data base concerning the natural radioactivity in building materials.
Key words: natural radioactivity; radon ; building materials.