Impact resistance-compressive strength relationship of steel fiber-reinforced concrete at ambient and high temperatures

Abstract

Despite the great scientific developments in fire resistance technologies and construction materials industry, fires threaten human lives and negatively impact the economy every day. One of the possible scenarios when a structure is subjected to accidental fire is the fragmenting of structural elements or falling of heavy objects from higher stories on fired concrete elements, which imposes a dual accidental loading. The aim of this research is to spotlight the relationship between the compressive strength and impact energy of concrete subjected to the dual action of high temperatures and repeated impacts. Cube and disk specimens from three mixtures with 0 %, 0.5 %, and 1.0 % of steel fibers were cast to investigate the compressive strength and repeated impact strength, respectively. Groups of specimens from each mixture were subjected to temperatures of 200 °C, 400 °C, and 600 °C in addition to the reference unheated specimens. The results showed that compressive strength and impact energy behave differently under the effect of high temperatures. However, regardless of the exposure temperature, the impact energy increases with the increase of compressive strength. This increase is more evident for failure impact energy compared to cracking impact energy. Simple linear and second order formulas were found suitable to describe these relations with R2values ranging from 0.71 to 0.96.