Behaviour of Sisal Fibre-Reinforced Concrete in Exterior Beam-Column Joints Under Monotonic Loading

Abstract

Concrete is the most widely used construction material because of its unique inherent properties, such as high compressive strength, good durability, fire resistivity, and low permeability. Aside from these positive properties are adverse characteristics, such as low tensile strength, brittleness, low resistance to cracking, and low impact resistance. These attributes made it necessary to investigate ways to improve the properties of concrete. Some of these deficiencies, such as low tensile strength, can be improved by incorporating optimum amount of certain fibers in concrete. Sisal is one of the numerous natural fibers that have shown great promise over the years. It possesses many advantageous properties, which include sustainability, high tensile modulus, and low cost. It is locally available in Kenya, Tanzania, and Brazil. It can be incorporated into the cementitious matrix to improve its mechanical strength, post-yield behaviour as well as inhibits crack propagation. In this study, the physical and mechanical properties of sisal fiber reinforced concrete was investigated. Durability performance in terms of strength and weight changes was reported at 45 and 90days. The concrete reinforced with sisal fiber was used to cast beam-column joints, the beam has a size of 150mmX150mm, 800mm long while the rectangular column was 150mmx200mm, 1m long. The joints were tested under monotonic load and verified using Finite element analysis. The Finite element analysis was done using Abaqus CEA where Concrete damage plasticity was used to model the concrete and uniaxial stress strain for the steel reinforcement. Sisal fiber with an aspect ratio of 230 and tensile strength of 373N/mm2 were added to the mix at 0.5%, 1.0%, 1.5% and 2.0% by weight of cement. A design mix ratio of 1: 1.92: 3.68 for cement: fine aggregates: coarse aggregates with a constant water to cement ratio of 0.47 was used. Physical tests carried out include workability on fresh concrete, density and water absorption on hardened concrete at 28 days. Mechanical tests carried out include compressive strength. Splitting tensile strength, Young’s Modulus and Poisson’s ratio. The crack pattern, ultimate load, ultimate deflection and shear capacity of beam-column joints made with sisal fiber reinforced concrete was also reported. The results shows that there was an improvement in splitting tensile strength and Young’s Modulus at 1.0% fiber incorporation. Sisal fiber plays a crucial role in arresting crack propagation. There was a general decrease in the compressive strength as the fiber content increased. However the performance of beam –column joints improved for all fiber content and Abaqus CEA can be used to model the behaviour of sisal fiber reinforced beam -column joints.