Enhanced flexural performances of cementitious composite beams with continuously graded steel fiber distribution

This paper focuses on improving the flexural behavior of steel fiber-reinforced beams with continuously graded structure. Successive vibrating after casting is assumed to be a feasible way to produce graded fiber-reinforced beams (GFRBs), resulting in fibers purposefully distributed in the tensile region. The fiber orientation and distribution are quantified through X-ray computed tomography (XCT). The porosity and pore size distribution are evaluated on the basis of XCT images and mercury intrusion porosimetry. Influences of fiber re-arrangement and microstructure on the compressive strength, the first-cracking strength, the ultimate flexural strength and the flexural toughness index are then investigated. The results show that: (1) the fibers deflect towards the longest side of the beam, and distribute more concentrated at the beam bottom, i.e. more fibers are available to withstand tension, due to the successive vibrating treatment; (2) the high vibration time does not induce a negative influence on the mortar matrix, but rather refines its microstructure with lower porosity and smaller pore size; (3) the flexural behavior is enhanced for fiber re-arrangement and microstructure improvement, revealing that the designed GFRB is capable of sustaining higher flexural strength and energy absorption capacity than the typically vibrated beam with the same fiber content.& COPY; 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This paper investigates the flexural behavior of steel fiber-reinforced beams with continuously graded structure (GFRBs). The distribution and orientation of fibers in the GFRBs are quantified using X-ray computed tomography (XCT). The re-arrangement of fibers and the refinement of the microstructure due to successive vibrating treatment are found to enhance the flexural behavior of the GFRBs, resulting in higher flexural strength and energy absorption capacity compared to typically vibrated beams.