Preliminary tests on high sulphate content aggregates for tunnel lining concrete

The 57 km length basis tunnel between St-Jean-de-Maurienne (France) and Susa (Italy) is a part of the future new railway Lyon-Turin. The works will generate about 43 Million tons of materials. To minimize the environmental impacts, the management of the excavated material become one of the basic issues of the sustainable development policy. A maximal valorisation of this material is then required. This valorisation could concern the transformation of excavated materials into concrete aggregates for the tunnel lining. Several studies have been carried out to evaluate the quality of the different types of materials which will be encountered into the tunnel. At this stage, 25% of the excavated materials are supposed to be valorised as concrete aggregates. Nevertheless the excavation of one of the access tunnel also showed that some materials have a sulphate content higher than those allowed by the EN 12620 to be used as concrete aggregates. Considering the dedicated quantity, the LTF company has then decided to support a research project to find out possible solutions to use this “sulphated” material. There’s still a long road in front of LTF, but this first tests campaign is bringing the confirmation of a possible use of those kinds of material.