Influence of steel fiber content and aspect ratio on the uniaxial tensile and compressive behavior of ultra high performance concrete

Abstract

This study investigates the effect of steel fiber contents of 1.5% and 3% with different aspect ratios on the uniaxial tensile and compressive behavior of ultra high performance concrete (UHPC). Compressive tests on concrete cylinders of 150mm×300mm and direct tension tests on notched prisms of 40mm×40mm×80mm were conducted. The test results indicated that there is no noticeable change in the compressive strength and elastic modulus with incorporation of steel fibers, however the post-peak behavior under compression is substantially affected by steel fiber content and aspect ratio. In terms of notched prisms under tension, there is no influence of steel fiber in the linear elastic stage, whereas the increase in steel fiber content results in not only a significant effect on the fiber activation stage but also higher values of fiber efficiency. Furthermore, the strain at the peak stress and the elastic modulus obtained from compressive tests were also evaluated by the comparison with some previous formulae. Finally, a relationship between the fiber efficiency σcf0 and the fiber factor K was proposed.