Development of a novel DNA-shaped steel fiber and its performance on fresh and hardened concrete

Abstract

Adding small discrete random fibers in concrete has enhanced concrete behavior in various ways. Diverse types of fibers are available in terms of materials, shapes, and applications. Different shapes of steel fibers are available like hooked ends, crimped, stranded, helix, spherical, etc. Having the grade of concrete and the fiber dosage added as constant, the structural behavior and performance will vary for different types of fibers. It shows that the shape of fiber has a great role in enhancing the properties of concrete. The challenges in existing two-dimensional steel fibers in concrete like the mechanism and contribution of fiber in arresting cracks developed in all directions and balling effect can be overcome by a new type of three-dimensional steel fiber. A novel three-dimensional DNA-shaped steel fiber is designed and fabricated. This paper presents the fresh concrete and hardened concrete properties of DNA-shaped fiber-reinforced concrete (DNAFRC) and compares it with hooked-end fiber-reinforced concrete (HEFRC) by incorporating a volume fraction varying from 0.5 to 2% of grade M30 concrete and aspect ratio of 60 for both fibers. The fresh properties of concrete were evaluated by measuring the slump for workability and wash-out test for the fiber distribution. The hardened concrete properties were assessed by compressive, split tensile, flexural, impact, shear, and pull-out strength which demonstrated considerable increase by 5% at 1.5% volume fraction, 32%, 136%, 21%, and 35% at 2% volume fraction respectively for DNAFRC than the HEFRC. Scanning Electronic Microscope (SEM) images were studied on failed samples to evaluate the bonding of DNA fiber with concrete.