Sprayed sUstainable PErmanent Robotized CONcrete tunnel lining

SUPERCON has now reached the end of the road. During the four years the project has lasted, we have been involved in and run scaled and full-scale tests on selected shotcrete recipes in a number of places. A number of recipes have been tested for an updated shotcrete that produces the desired effects; still retain a certain early strength, the same long-term strength and at the same time with reduced cracking during curing. The project carried out a final test in the Hestnes tunnel at Mjøsa where final prescriptions were tested. It may turn out that a waterproof shotcrete is out of reach, but that it is possible to establish shotcrete with significantly less cracking and close to being watertight, or as we have called it 'functional dry'. In a tunnel context, this may be a more appropriate goal for the work than establishing a waterproof shotcrete. Work is now underway on a final report from the project, which will be published and made available to the tunnel industry. It will primarily be made for the Norwegian market and will therefore be published in the Norwegian language. There is certainly a need to meet the challenges climate politicians promote on a general basis, and a shotcrete that has a lower cement content, as we have concluded in our research, is one contribution to these endeavours.

The project has increased the understanding and competence on how sprayed concrete structurally behaves, how its water tigthness appears and the potential to become watertight. A lot of testing has been performed for the sake of identifying a mix design that reduces the shrinkage cracking, reduces the sement content, reduces the CO2-emission, reduces the permeability and finally becomes as water tight as practically possible. Still, the mix design must produce a sprayed concrete mix that remains to be pumpable and sprayable. The project has reached a level where it can be concluded that all these goals have been met, except that making a water tight solution may not be achievable. The project has decided that it can be concluded that a sprayed concrete mix design which is producing a solution that is functionally dry has been acj\hieved.

The SUPERCON proposal is a counterweight to a trend in Norwegian tunnelling projects towards adopting the "European way" of tunnelling, with in-situ casting or pre-cast segment lining. The European Way requires high concrete volumes, resulting in increased materials consumption and costs, with negative environmental loads and costs. SUPERCON aims at producing thin sprayed concrete layers with the quality to act as temporary support during construction and permanent lining over the service life of tunnels. The primary objective is to provide the tunnelling industry with the required knowledge to produce Sprayed sUstainable Permanent Robotized CONncrete tunnel linings, which meet modern demands for functionality, sustainability and eco-friendliness in new infrastructure projects, such as Ringeriksbanen and The Ferry-free E39, without compromising the environment. Improvement of robustness and durability shall reduce cost and environmental loads for the public infrastructure owners. This multidisciplinary project will focus on complex challenges involving structural-, civil production- and geological engineering. Theoretical, numerical modelling, laboratory and full-scale investigations are planned to study the decisive parameters and processes that control technical quality, as well as sustainability of the lining. The most critical R&D challenges of the project are to: 1) compose sustainable materials fulfilling also technical requirements, 2) establish measurement methods to quantify key parameters such as spray-ability, 3) model and design crack-free thin shell solutions, 4) measure lining permeability and durability, 5) investigate the environmental performance in varying scenarios by LCA inventory and, 6) bring the knowledge to the industry to make it competitive and profitable. SUPERCON includes; NTNU, SINTEF, NGI, AMV, BASF, Bekaert Maccaferri, Bever Control, Entreprenørservice, Elkem, Norcem, SWECO, Veidekke, Wacker, Bane Nor, Nye Veier, SVV