Effect of Fibre Dosage on the Permeability and Mechanical Properties of Steel Fibre Reinforced Concrete

Steel fibre reinforced concrete (SFRC) is a composite material whereby discontinuous steel fibres are randomly distributed throughout the concrete matrix. Since concrete is weak in tension, the fibres compensate for the lack of tensile capacity by improving the post-cracking ductility. It also enhances the concrete’s toughness, resistance to cracking, and fatigue life. The fibre volume dosage, fibre type, and fibre geometry, among others, are typically factors that influence the post-cracking behaviour of fibre reinforced concrete (FRC). While these factors may vary depending on the nature of the application, they not only influence the post-cracking behaviour, but the durability of the SFRC may also be compromised. Cracks at the surface of the concrete create ingress pathways for deleterious substances which may affect the durability of the composite. This research aims to investigate the mechanical behaviour and durability properties of uncracked hooked-end SFRC with fibre volume dosages varying from 0% to 1.0%. The results show an increase in mechanical properties with an increase in fibre volume dosage. In contrast, the durability properties showed improved oxygen permeability and minimal carbonation penetration at a 0.5% fibre dosage. However, an increase in the fibre dosage to 1.0% resulted in a decrease in oxygen permeability and an increase in carbonation, thereby illustrating the need to optimize the fibre dosage for favourable mechanical and durability properties.