Numerical and Experimental Study of the Effect of Simultaneous Adding Steel and Polypropylene Fiber on the Strength of Sleeper Concrete with an Approach to Achieve Optimal Percentage of the Fiber (Case Study: Sleeper Concrete Manufacturing Factory of Karaj)

In the last recent decades, the rail transport system for transit of humans has been expanded as one of the most convenient and low-cost transportation systems. As one of the most important elements of the railway lines is sleeper concrete, thus, the issue of operation and maintenance of this system has special importance. In this research, concrete strength has been improved by simultaneous addition of steel and polypropylene fibers to sleeper concrete (manufactured at Sleeper Manufacturing Factory in Karaj, Iran). A total of 120 cylindrical and prismatic samples were constructed for testing compressive, tensile, and flexural strength in eight different designs. Total percentage of fiber used in each design was 1%. According to the results, the best design for compressive and tensile strength was design number 8 (1% steel fiber, 0% polypropylene fiber) and for flexural strength was design number 6 (0.6% steel fiber, 0.4% polypropylene fiber). Presence of fiber in sleeper concrete can reduce its pre-stressed reinforcement by 40% and prevent occurrence of deep cracks.