Evaluation of the mechanical properties of steel and polypropylene fibre-reinforced concrete used in beam column joints

Investigations on improving characteristics of concrete structures utilizing fibre reinforced concrete (FRC) have gained momentum in the last few decades. Using suitable fibres and additives in concrete to advance its performance is an important consideration in the construction industry. With regards to structural aspects of concrete, the important goal of this project is to improve the ductility of the concrete beam column joints, which helps eliminate or reduce the need for steel reinforcement. Fibres within the matrix, can bridge the cracks, which improves the performance of concrete matrix and results in a better stress bearing concrete material. This research project aims to investigative the effect of polypropylene (PP) and steel fibre volume percentage within the concrete on its mechanical properties. Concrete fresh properties as well as hardened properties have been tested and evaluated to work out the best fibre percentage to be added to concrete structure. From among the trial mix designs, five sets of FRC have been fully tested for the mechanical properties and also evaluated for the beam column concrete joint behaviour. Slump, mass per unit volume and air content have been tested to work out the fresh properties of concrete. 7 and 28-day compressive strength and also indirect tensile tests have been performed on the hardened concrete the results of which are presented in this paper. By using 0.5% by volume fraction of 30mm steel fibre, the indirect tensile strength of concrete has increased by 21%; however, when 1% of steel fibre has been utilized, about 45% increase has been observed. Furthermore, a sample of the joint test conducted will be presented in this work to illustrate the finite goal of this project