A study on natural radioactivity and radon exhalation rate in building materials containing norm residues: preliminary results F. Leonardi a,⇑ , M. Bonczyk b , C. Nuccetelli c , M. Wysocka b , B. Michalik b , M. Ampollini c , S. Tonnarini a , J. Rubin d , K. Niedbalska e , R. Trevisi a a INAIL (National Institute for Insurance Against Accidents at Work) – Research Sector, DiMEILA, Via di Fontana Candida 1, 00078 Monteporzio Catone (Rome), Italy b GIG (Glówny Instytut Górnictwa), S ´ la ˛ skie Centrum Radiometrii S ´ rodowiskowej Plac Gwarków 1, 40-166 Katowice, Poland c ISS (National Institute of Health), National Center for Radiation Protection and Computational Physics, Viale Regina Elena, 299, 00161 Rome, Italy d PSl (Politechnika S ´ la ˛ ska), Katedra Procesów Budowlanych, ul. Akademicka 5, 44-100 Gliwice, Poland e GIG (Glówny Instytut Górnictwa), Zaklad Geologii i Geofizyki, Plac Gwarków 1, 40-166 Katowice, Poland highlights  Natural radionuclides content in building materials added with NORM.  Radon exhalation in concrete added with NORM.  Intercomparison of radon exhalation rate results.  Effect of the concrete microstructure on radon exhalation rate. article info Article history: Received 29 September 2017 Received in revised form 26 March 2018 Accepted 27 March 2018 Available online 24 April 2018 Keywords: Radon exhalation rate Building materials Concrete Natural radionuclides content abstract This paper contains preliminary results of a study on the physical and radiological characterization of concrete samples containing NORM. The natural radionuclides content in term of 226 Ra, 228 Ra, 232 Th, 40 K and the radon exhalation rate of the samples were determined. Two series of samples of concrete were prepared: samples belonging to both series were made of the same basic components (Portland cement CEM I 42,5R as binder, aggregate and plasticizer) but different amount of NORM residues and mineral additives were used. The concrete samples were characterize in term of absolute density, permeability, total and open porosity. The radiological content was evaluated by using gamma spectrometry and the radon exhalation rate measurements were performed using the dynamic method. Moreover, the Activity Concentration Index (I), introduced by the 2013/59/Euratom Directive, has been used in order to evaluate if concrete samples could exceed the reference level for effective dose due to gamma radiation in building materials. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction The European Commission in 2011, launched its ‘‘Roadmap for Resource-efficient Europe” [1] in which three action lines are sta- ted. In particular, in the first one, named ‘‘Transforming the econ- omy” turning waste into a resource is clearly indicated. This is intended that the European Commission will stimulate secondary materials markets in order to move towards an economy based on re-use and recycling. In this framework, the use of raw materi- als for building material production is discouraged while the use of secondary or residue-derived materials is promoted. In this particular frame, the attention of regulators and researchers was focused on large amount of residues produced by NORM (Naturally Occurring Radioactive Material) industries, which can be recycled as secondary raw materials in building products. Indeed, although recycling NORM residue into building materials brings significant beneficial effect on environment and sustainability, the consequent enhanced radionuclide content may have an impact on human health due to a potential increase of gamma exposure and of indoor radon activity concentration. As consequence, the Council Directive 59/2013/Euratom (EU BSS in the following) [2] considers the protection of the population from gamma radiation emitted from building materials in its scope. Moreover, the EU BSS takes into account the possible contri- bution of building materials as indoor radon source among the https://doi.org/10.1016/j.conbuildmat.2018.03.254 0950-0618/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: f.leonardi@inail.it (F. Leonardi). Construction and Building Materials 173 (2018) 172–179 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat