Durability of Shotcrete Tunnel Linings due to Steel Fibre Corrosion in Cracks

Abstract: ABSTRACT Steel fibre reinforcement in homogenous, intact, wet-mix shotcrete show an excellent durability against corrosion. The alkaline concrete environment gives good protection but the relatively thin shotcrete layers may crack due to shrinkage and other deformations. Durability requirements today often demands service-life of more than 100 years, which is not realistic with a maintained load-bearing capacity. Special measures must therefore be taken in the design of shotcrete rock support, such as addition of extra amount of fibres if the shotcrete is cracked or increased structural thickness, which is here demonstrated with examples. Due to the complex situation with requirements on service-life, climate impact and cost-efficiency, the design of future shotcrete supports will be optimized based on life cycle and life cycle cost analyses.