Effect of steel fiber content on structural and electrical properties of ultra high performance concrete (UHPC) sleepers

This experimental research investigates the structural and electrical responses of ultra-high performance concrete (UHPC) railway sleepers with three different levels of steel fiber content. The UHPC sleepers used in this research were fabricated using a conventional concrete sleeper manufacturing process including the post -tensioning method. They were then evaluated via static bending tests at the rail-seat section and via electrical insulation performance tests. Test results indicate that UHPC sleepers with all three levels of steel fiber content sufficiently meet international requirements. The results from the first cracking load and the load when a crack width becomes 0.05 mm indicate that an amount of steel fiber greater than 1% is required to effectively control early-stage crack development in UHPC sleepers. In addition, the relationship between fiber volume fraction and normalized strength highlights that the material characteristics of UHPC, especially its tensile capacities, correlate strongly with the structural behavior of UHPC sleepers.