Effects of Waste Steel Fibers on Strength and Stress-strain Behavior of Concrete Incorporating Silica Nanopowder

摘要

In the present experimental work, strength and stress-strain behavior of steel fiber reinforced concrete (SFRC) containing silica nanopowder has been investigated. The fibers used were waste steel slivers recovered from industrial wastes. First some tests were carried out in order to determine the characteristics of the Waste Steel Fibers (WSF). Different weight ratios of WSF as 0, 1, 3 and 5 wt% were introduced into the concrete mix and the behavior of FRC samples were investigated under compression. A fraction of the cement as 3 wt% was also replaced by silica nanopowder. The results showed that introducing the WSF up to 5wt% could improve the strength and ductility of the concrete. Besides, more uniform distribution of cracks was observed. Addition of nanopowders as 3wt% also resulted in enhanced strength of the concrete which could be due to more packed and refined microstructure of the concrete and also more integrity of the fibers with the concrete mix. Silica nanoparticles as a partial replacement of cement could accelerate C-S-H gel formation as a result of increased crystalline Ca(OH)2 amount at the early age of hydration and hence increase the strength of concrete specimens.