Naturally occurring radioactivity in some Swedish concretes and their constituents - Assessment by using I-index and dose-model

The reference level for effective dose due to gamma radiation from building materials and constructionproducts used for dwellings is set to 1 mSv per year (EC, 1996, 1999), (CE, 2014). Given the specificconditions presented by the EC in report 112 (1999) considering building and construction materials, anI-index of 1 may generate an effective dose of 1 mSv per year. This paper presents a comparison of theactivity concentrations of 40K, 226Ra and 232Th of aggregates and when these aggregates constitute a partof concrete. The activity concentration assessment tool for building and construction materials, the Iindex,introduced by the EC in 1996, is used in the comparison. A comparison of the I-indices values arealso made with a recently presented dose model by Hoffman (2014), where density variations of theconstruction material and thickness of the construction walls within the building are considered. Therewas a ~16e19% lower activity index in concretes than in the corresponding aggregates. The model byHoffman further implies that the differences between the I-indices of aggregates and the concretes' finaleffective doses are even larger. The difference is due, mainly to a dilution effect of the added cement withlow levels of natural radioisotopes, but also to a different and slightly higher subtracted backgroundvalue (terrestrial value) used in the modeled calculation of the revised I-index by Hoffman (2014). Onlyvery minimal contributions to the annual dose could be related to the water and additives used, due tot heir very low content of radionuclides reported.QC 20210428</p

Design

International audienceThis chapter reviews the design methods typically use of designing Bonded Concrete Overlays (BCO). Two levels of design are discussed : the design for strength and the design to resist debonding. For the design for strength various methods are discussed : U.S. Army Corps of Engineers, Portland Cement Association, American Association of Highway and Transportation Officials, reinforcement design of overlaid continuously reinforced concrete pavements and procedures from other countries. For design to resist debonding, methods from the U.S., Sweden, Japan, other countries in Europe are described