Influence of Using Various Types of Steel Fibers of Recycled Concrete Aggregates on the Shear Behavior of RC Beams

Abstract

This study aims to determine the efficiency of concrete containing multiple recycled materials, recycled concrete aggregates (RCAs) and recycled steel fibers (RSFs), and compare it with conventional concrete. Natural coarse aggregate (NCA) in the concrete mix was partially replaced with 30% RCA to achieve a target compressive strength of 30 MPa after 28 days. Different types of fibers (steel fibers, RSFs, and mixed fibers) were added at varying percentages (1.0%, 1.5%, and 2.0%) to improve the mechanical properties of the concrete mixes. The shear behavior of reinforced concrete beams containing RCA and different types of fibers was investigated. Ten concrete mixtures were designed, and 10 reinforced concrete beams were tested under a two-point load to estimate the contribution of various fiber types to the shear resistance. The results indicate that the addition of different types of fibers significantly enhances compressive, tensile, and flexural strengths of the concrete. Specifically, the improvement in compressive strength for RSFs was 38.9% at 1.5%, tensile strength improved by 21.1%, and flexural strength by 46.2% at the same fiber percentage, thereby improving the concrete's ability to resist cracks through an increase in shear resistance.