Influence of high temperatures on the mechanical and microstructural properties of hybrid steel-basalt fibers based ultra-high-performance concrete (UHPC)

Abstract

One of the major problem in ultra-high-performance concrete (UHPC) after exposure to high-temperatures is explosive spalling. Adding a single type of fibers alone is insufficient sometimes for suppressing such spalling, and therefore, hybridization of fibers has been adopted, particularly steel with organic fibers. However, the degradation of organic fibers at ambient and elevated temperatures is a significant challenge in the long term and needs to be addressed. Recently, inorganic basalt fibers have been considered as an alternative to organic fibers due to their better mechanical strength and high-temperature resistance characteristics. In this study, hybridizing steel with basalt fiber is proposed as a potential solution to the aforementioned problem. The spalling behavior, residual compressive strength, microstructure, porosity, hydration kinetics, phase decomposition, and quantification of hydration products were evaluated for hybrid steel-basalt fiber reinforced UHPC after exposure to high-temperatures. The study results indicated that hybrid steel-basalt fiber reinforced UHPC successfully prevented explosive spalling behavior. The use of inorganic mineral basalt fibers offers a promising solution for developing UHPC with superior high-temperature resistance.