Effect of hybridization of straight and hooked steel fibers and curing methods on the key mechanical properties of UHPC

This paper presents a study on evaluating the effect of two key factors, namely, the hybridization of straight and hooked steel fibers and curing methods, on the mechanical properties of ultra-high-performance concrete (UHPC). The UHPC specimens using the same proportions of the water, binder, and filler were prepared considering five different combinations of straight and hooked steel fibers. The UHPC specimens were subjected to normal water curing and steam curing. The mechanical properties studied included the compressive strength, flexural strength, modulus of elasticity, flexural toughness, and steel-UHPC bond characteristics considering steel bars of two different strength grades (G60 and G230). The experimental data were used to discuss the effects of both the hybridization of steel fibers and curing methods on the mechanical properties of UHPC as well as to conduct an analysis of variance (ANOVA) and to obtain the empirical models correlating the variables with the mechanical properties. The test results exhibited a significant effect of the hybridization of the fibers on the studied properties of UHPC. The UHPC containing a higher amount of hooked fibers significantly enhanced the modulus of elasticity, flexural tensile strength, and flexural toughness. The performance of UHPC cured using steam was found better than that cured using water in all aspects. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study evaluated the effects of hybridization of straight and hooked steel fibers and curing methods on the mechanical properties of ultra-high-performance concrete (UHPC). The results showed that a higher amount of hooked fibers significantly improved the modulus of elasticity, flexural tensile strength, and flexural toughness of UHPC. UHPC cured using steam exhibited better performance compared to water curing in all aspects.