Mechanical properties of high-performance hybrid-fibre-reinforced cementitious composites (HPHFRCCs)

Abstract

Specially processed steel cord (SC) macrofibres, each consisting of five twisted steel fibres, are used to improve the post-cracking behaviour of cementitious composites. The long steel cords have a large diameter, and are characterised by high tensile strength, frictional bond strength and flexural rigidity. In addition to these steel cord macrofibres, microfibres are used to enhance the snubbing strength and total tensile behaviour of the composite. The two specific hybrid fibre blends studied in the present paper are SC and polyethylene (PE), as well as SC and polyvinyl alcohol (PVA) fibres. The objectives of the current study are to explore the mechanisms by which fibres interact with the composite matrix, and to provide a rigorous characterisation of the performance achievable with hybrid-fibre-reinforced cementitious composites (HFRCCs). Cement- based composites containing large volume fractions ( 1.0 similar to 2.3%) of various hybrid fibres were compared in terms of flow and fibre dispersion, as well as compressive, splitting tensile, flexural and uniaxial tensile properties. The workability of HFRCCs is governed by the high surface area of the microfibres. The results confirm that the flexural strength, tensile strength and ductility (pseudo-strain-hardening) of HFRCCs are tremendously improved in comparison with mortar or monofibre systems. Furthermore, there is a synergy effect in the microfibre and macrofibre hybrid systems.