title: Naturally occurring radioactivity in some Swedish concretes and their constituents - Assessment by using I-index and dose-model.
abstract: The reference level for effective dose due to gamma radiation from building materials and construction products used for dwellings is set to 1 mSv per year (EC, 1996, 1999), (CE, 2014). Given the specific conditions presented by the EC in report 112 (1999) considering building and construction materials, an I-index of 1 may generate an effective dose of 1 mSv per year. This paper presents a comparison of the activity concentrations of (4)(0)K, (226)Ra and (232)Th of aggregates and when these aggregates constitute a part of concrete. The activity concentration assessment tool for building and construction materials, the I-index, introduced by the EC in 1996, is used in the comparison. A comparison of the I-indices values are also made with a recently presented dose model by Hoffman (2014), where density variations of the construction material and thickness of the construction walls within the building are considered. There was a ∼16-19% lower activity index in concretes than in the corresponding aggregates. The model by Hoffman further implies that the differences between the I-indices of aggregates and the concretes' final effective doses are even larger. The difference is due, mainly to a dilution effect of the added cement with low levels of natural radioisotopes, but also to a different and slightly higher subtracted background value (terrestrial value) used in the modeled calculation of the revised I-index by Hoffman (2014). Only very minimal contributions to the annual dose could be related to the water and additives used, due to their very low content of radionuclides reported.
authors.affiliation: Swedish Cement and Concrete Research Institute (CBI), c/o SP, Box 857, SE-501 15 Borås, Sweden. Electronic address: magnus.dose@cbi.se.
authors.forename: M
authors.initials: M
authors.lastname: Döse
authors.affiliation: Royal Institute of Technology (KTH), Department of Civil and Architectural Engineering, Brinellvägen 23, SE-100 44 Stockholm, Sweden. Electronic address: jsilfwer@kth.se.
authors.forename: J
authors.initials: J
authors.lastname: Silfwerbrand
authors.affiliation: Geological Survey of Sweden, Box 670, SE-751 28 Uppsala, Sweden. Electronic address: cecilia.jelinek@sgu.se.
authors.forename: C
authors.initials: C
authors.lastname: Jelinek
authors.affiliation: Swedish Cement and Concrete Research Institute (CBI), Drottning Kristinas väg 26, SE-100 44 Stockholm, Sweden. Electronic address: jan.tragardh@cbi.se.
authors.forename: J
authors.initials: J
authors.lastname: Trägårdh
authors.affiliation: University of Gothenburg, Institute of Clinical Science, Department of Radiation Physics, Gula Stråket 2B, Sahlgrenska University Hospital, SE-413 45, Göteborg, Sweden. Electronic address: mats.isaksson@radfys.gu.se.
authors.forename: M
authors.initials: M
authors.lastname: Isaksson
mesh_terms: D003252:Construction Materials / Q000592:standards*; D005720:Gamma Rays; D008962:Models, Theoretical; D011197:Potassium Radioisotopes / Q000032:analysis*; D011829:Radiation Dosage; D011834:Radiation Monitoring; D011883:Radium / Q000032:analysis*; D012016:Reference Values; D013051:Spectrometry, Gamma; D013548:Sweden; D013910:Thorium / Q000032:analysis*
chemical_list: D011197:Potassium Radioisotopes; D013910:Thorium; D011883:Radium
keywords: Aggregates; Building materials; Concrete; Construction product; Dose model; I-index; Radioactivity