Print Email Facebook Twitter Influence of the porosity on the 222RN exhalation rate of concrete Title Influence of the porosity on the 222RN exhalation rate of concrete Author de Jong, P. van Dijk, W. de Rooij, M. Publication year 2011 Abstract The composition of 23 concrete mixtures was varied in five separate series to evaluate the influence of porosity on the 222Rn exhalation rate. In each series, a range in porosities is obtained by varying (1) the amount of cement, (2) type of cement (Portland or blast furnace slag cement), (3) the amount of water at a fixed cement level, (4) addition of an air entraining agent, or (5) the amount of recycled aggregates. The porosities ranged from 1% to 16%. The 222Rn exhalation rate is normalized to the 226Ra activity concentration and expressed as the 222Rn release factor to eliminate the effect of differences in 226Ra activity concentrations among the various concrete mixtures. Since most 222Rn originates from the cement, a 222Rn release factor based on the amount of 226Ra introduced by the cements appeared to be more adequate. Although the methods to attain the porosities in the concrete mixtures differ widely, this cement-related factor corresponds well with the capillary porosity of the mixtures. Since the water-to-cement ratio of the fresh paste is a good indicator of the capillary porosity, this is the guiding factor in the fabrication of concretes low in 222Rn exhalation. The lower the water-to-cement ratio, the less capillary pore area will be available from which 222Rn can emanate from the mineral matrix into the pore system. The good correlation between the cement-based 222Rn release factor and literature data on the internal capillary pore area support the results of this study. Copyright © 2011 Health Physics Society. Subject Mechatronics, Mechanics & MaterialsMIP - Materials for Integrated ProductsTS - Technical SciencesGeosciences<sup>222</sup>RnDiffusionExhalation rateIndoorNaturalRadioactivity To reference this document use: http://resolver.tudelft.nl/uuid:8a7afe6c-e8fe-4b71-91b1-5d733f770635 DOI https://doi.org/10.1097/hp.0b013e3181ed345b TNO identifier 426803 ISSN 0017-9078 Source Health Physics, 100 (2), 127-137 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.