Mechanical Properties of Fibre Reinforced Concrete Incorporating Recycled Tyre Steel Fibres and Industrial by-Products as Aggregates

The main objective of this work is to investigate the properties of a Fibre Reinforced Concrete (FRC) at fresh and hardened states, obtained by a partial substitution of coarse and fine natural aggregates with Electric Arc Furnace Slag (EAFS) and Fly Ash (FA). Recycled Tyre Steel Fibres (RTSF) were incorporated in the developed concrete in order to maximize and reuse wastes that were not biodegradable. The design of the FRC mixture with EAFS was based on a reference concrete by using the modified Andreasen and Andersen particle-packing model. The composition was optimized to achieve maximum packing density. Workability, compressive and tensile splitting strength, modulus of elasticity and post-cracking behaviour were evaluated for the different concrete mixtures developed and compared to the ones of the reference mixture. The selected concrete composition, with an EAFS and FA maximum content of 70% and 10%, respectively, has shown good workability and suitable elasticity modulus according to the specified requirements. The latter mixture revealed a lower compressive and tensile splitting strength, comparatively with the reference mixture (w/o fibres), which was compensated by the improved ductility and energy absorption capacity under compressive loading.