The construction of a 57 km length base tunnel for the future railway link between Lyon (France) and Turin (Italy) promoted by Lyon Turin Ferroviaire (LTF), subsidiary of Réseau Ferré de France (RFF) and Rete Ferroviaria Italiana (RFI), will result in the production of 16 millions of m3 of excavated materials. In order to promote efficient and sustainable management of natural resources and to reduce greenhouse gas emission and environmental impact, one wish of LTF is to use the most part of these materials as concrete aggregates. However, a part of the excavated materials from LTF tunnel has a sulphate content between 1.46 and 4.30% (expressed in mass of SO3) and cannot be used considering the European standards, which drastically limit the sulphate content in order to avoid structural damages resulting from internal sulphate attack. The sulphate content is limited to 0.2% for this type of construction. The first study, carried out in order to define solutions for the use of these excavated materials, focuses on the behaviour of sulphates, more particularly on their leaching in solution in order to determine the sulphate content that could be released in the concrete. The results show that the sulphates are quickly available for the particles size lower than 4 mm. The washing of excavated materials before their use in concrete can be a solution to limit the internal sulphate attack. The second study has been conducted in order to define a suitable cement for the use of excavated materiels as aggregates. A comparative study of different cements supposed to be resistant to sulphates has been carried out. Three accelerated tests have been developed to assess the risk of degradation of cementitious materials by formation of ettringite and thaumasite. Only two cements show a good behavior against the internal sulphate attack resulting from sulphated aggregates. These cements are a Portland cement with a very low calcium aluminates and alkaline contents and an over sulphated cement.In the frame of a third study, an innovative solution has been proposed and concerns the using of excavated materials as a source of sulphates for regulating the hydration of cement. Sulfates from the excavated sand can regulate the cement hydration and then cancel any further damage due to sulphates
