An Experimental Study on Mechanical Properties and Cracking Behaviors of AFRC Used as Functional Material in Hybrid Beams

Abstract

In this paper, the effects of a constant fiber volume fraction (1%) of four types of aramid fibers (AFs) and one type of steel fiber (SF) on mechanical properties, load capacity, and cracking behavior of concrete were investigated. To use fiber-reinforced concrete (FRC) as a functional material economically, hybrid beams having FRC in the bottom half and normal concrete in the top half of the beam section were designed. A total of 108 cylindrical specimens of conventional concrete, aramid fiber-reinforced concrete (AFRC), and steel fiber-reinforced concrete (SFRC) were tested to explore the effects of various fibers on the compressive and splitting tensile strengths. The effects of the fibers on the load carrying capacity and cracking behaviors of the beams were studied through two-step four-point bending tests of a control beam and five hybrid beams. The experimental results showed that the use of AFs and SF in concrete enhanced the splitting tensile strength, cracking behavior, and ductility. However, the use of fibers was found to have an insignificant effect on the compressive strength of concrete. Among the tested aramid and steel fibers, the performance of the twisted aramid fibers with 40 mm length (40-T) was the most impressive with respect to an enhancement of tensile strength, load capacity, and cracking behavior. Furthermore, a comparison of various properties of AFRCs and SFRC indicated that 40-T aramid fiber can be used as an alternative to steel fiber.