Different studies on building materials

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 graniticmaterials are being used as ornements or integrated on the walls inside the houses, producing highindoor radon levels. Studies of different coverings for granitic materials were tested employing incolorpaintings in order to reduce the radon exhalation from such granitic stones, without modifying theirappearance. 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 226Ra,232Th, 40K, as well as radon exhalation from building materials usually employed in construction.Analyses of the correlation between 226Ra content and radon exhalation from those materials were alsoperformed. 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 amembrane and act as radon barrier. A selection of such materials was also performed accordingly theireffectiveness. 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 naturalgypsum. Studies were carried out, using phosphogypsum mixtures having different percentages of aninert material. These experiments had the aim to reduce the radon exhalation and to provide a mixturethat 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.