Radioactivity and radon exhalation rates of building materials in The Netherlands

About 140 samples of building materials have been analysed by gamma spectrometry for their Ra-226, Th-232 and K-40 concentrations. The radon exhalation rate was measured from concrete slabs of different composition including fly-ash components. The activity concentrations of materials containing soil products, like clay bricks and concrete, proved to be somewhat lower than those reported in some other European countries. This is probably due to the mainly sedimentary structure of the Dutch soil. The normalized radon exhalation rates were found to be substantially lower for concrete containing fly-ash products than for ordinary concrete.