ABSTRACT
When designing concrete mixes for tunnelling, the focus is increasingly on ecology as well as mechanical properties, durability, and economy. To meet all the requirements placed on tunnelling structures, it is important that the raw materials used are well selected. The focus of this article is to help in the selection of a suitable steel fibre for the respective concrete mix design to achieve all the required properties - for both fresh and hardened concrete - with the lowest possible carbon footprint. On the one hand, precast concrete elements - tunnel segments - and on the other hand, sprayed concrete mix designs are considered. While the influence of steel fibres and the effects of binder optimization on the CO2-footprint are also shown for the tunnel segments, the focus for the sprayed concrete mix designs is on the steel fibres. The results are presented based on two case studies.
