Low CO2 binder solution resisting extreme sulfate attack in real conditions of the new European railway tunnel at Mont Cenis

15th International Congress on the Chemistry of Cement : ICCC 2019, PRAGUE, TCHÈQUE, RÉPUBLIQUE, 16-/09/2019 - 20/09/2019The new high-speed railway link between Lyon (France) and Torino (Italy) of the Trans-European Transport Network must pass peculiar geological strata containing numerous large patches of very pure gypsum and anhydrite which will contaminate neighbouring high grade mineral layers. For the new base-tunnel with more than 57 km of length it was calculated that some 2 million tons of material dedicated to concrete aggregate production will have a sulfate content over 0.2 %, maximum value of EN 206. In order to avoid high disposal costs and thus being able to use most of the excavated material a comprehensive long-term durability study was started a couple of years ago. This study mainly focuses on extreme internal sulfate attack and ranged from initial lab tests up to careful monitoring of expansion reactions of large concrete structures stored in one of the already realized exploration galleries in the French Alps. In all those tests it could be demonstrated that concretes prepared with supersulphated slag (called here CSS) as binder component not only shows superior resistance against sulphate attack but also develops very favourable performance towards other durability parameters such as Alkali-Aggregate Reaction AAR. These results confirm the evidence of earlier studies on the durability of CSS, for instance the one of Evans, Blaine and Worksman presented in 1960 at the 4th ICCC in Washington D.C. As furthermore CSS is practically devoid of clinker (cf. standard EN 15743), a multi-faceted and sustainable eco-friendly solution can be offered for the realization of this railway link