Comparative Evaluation of Steel, Glass and Polypropilene Fiber Reinforced Shotcretes for Tunnel Lining

The present paper deals with the use of different types of fiber to reinforce shotcrete for tunnel linings. Experimental investigations were performed on steel (SF), glass (GF) and polypropylene fibers (PF) reinforced concretes and shotcrete (manufactured with a silicate based set-accelerating admixture) in order to compare rheological and mechanical behavior of fiber reinforced mixtures with respect to plain concrete (without fibers: PL). No influence of fibers was observed on rheological properties. Shotcrete rebound was not affected by the type of fiber, but it seems to be closely related to the dosage of set-accelerating admixture. The mechanical properties were strongly influenced by both the casting method (casting for concretes and spraying for shotcrete) and the dosage of set-accelerating admixture rather than the type and dosage of fibers used.