Experimental study on the strength properties of concrete modified with silica fume and steel fiber

Abstract

Concrete is a widely used building material. It has excellent compressive strength but is brittle and relatively weak in tension. This experimental study aims to develop ductile and high-strength concrete by incorporating silica fume and steel fibers. Two types of steel fibers with aspect ratios of 52 and 72 were employed at varying percentages (0.44%, 0.88%, and 1.76% by mass of cement content). Additionally, 8.5% silica fume by cement mass was added to the concrete mixture. A water-to-cement (W/C) ratio of 0.42 and a slump of 100 mm are maintained. Substituting cement with silica fume improves the concrete's mechanical properties and elastic modulus. Moreover, adding steel fibers enhanced flexural and tensile strength. Increasing the percentage of silica fume and steel fibers correlated with higher compressive strength, while the aspect ratio of steel fibers has an inverse effect on compressive strength, with lower aspect ratios exhibiting a higher compressive strength. Furthermore, as the percentage of silica fume and steel fibers increases, the splitting tensile and flexural strength also improve, with the aspect ratio directly influencing these strengths, higher aspect ratios resulting in superior tensile and flexural strength. Ultimately, this investigation demonstrates that the strength properties of concrete rely on the content of silica fume, steel fibers, and the aspect ratio of the steel fibers.