Mechanical properties of steel fiber-reinforced UHPC mixtures exposed to elevated temperature: Effects of exposure duration and fiber content

In the present study, ultra-high performance concrete (UHPC) mixtures reinforced with varying dosage of steel fibers were considered for studying the effects of exposure duration and fiber content on mechanical properties of the mixtures subjected to a sustained pre-spalling elevated temperature of 300 °C for different durations. Test results showed an increase in compressive strength and modulus of toughness even after exposing to elevated temperature for 5 h. However, modulus of elasticity and flexural strength decreased significantly with increase in exposure duration. The experimental data were statistically analyzed using analysis of variance (ANOVA) method to examine the effects of fiber content and exposure duration on the mechanical properties. Empirical equations were obtained with excellent degrees of fit correlating the mechanical properties of UHPC mixtures with fiber content and exposure duration.