Benefits of blast furnace slag and steel fibers on the static and fatigue performance of prestressed concrete sleepers

This study investigates the influence of the use of steel fibers and ground granulated blast furnace slag (GGBFS) on the static and fatigue performance of prestressed concrete sleepers. Two series of sleepers with a partial replacement of type III cement by GGBFS (56% by weight of the binder) were tested and the performances of these sleepers were compared to conventional railway sleepers. One series of sleepers were reinforced with the same number of prestressing strands (sixteen strands) as conventional railway sleepers, while the other series of sleepers had a reduced number of strands (fourteen strands). Each series consisted of two types of sleepers with (v_f = 0.75%) and without steel fibers. Static and fatigue tests causing positive moments at the rail seat section and additional static tests causing negative bending moments at the center section of the sleepers were carried out. The sleepers produced with GGBFS showed improved static flexural and fatigue performance at the rail seat section compared to conventional sleepers with Type III cement. The addition of steel fibers instead of conventional stirrups resulted in increased flexural and fatigue capacity at the rail seat section by controlling crack propagation and by preventing brittle shear failure. The performances of all sleepers at the center section were quite similar. The combination of the reduced number of strands together with steel fibers improves the performance and achieves greater economy.