Improving reinforcement efficiency of aligned steel fibre on cement-based composites by hybridizing polypropylene fibre

Steel fibres have the advantages of high strength, elastic modulus, bonding strength with cement matrix, and can be aligned by using a magnetic field to improve the efficiency of reinforcement. However, compared to synthetic fibres, in cementitious matrix the number of steel fibres is much smaller and the space between steel fibres is quite large, which may lead to the existing of weak regions between steel fibres. Hybridizing polypropylene (PP) fibres has the advantages of large number and small space between fibres, which may effectively compensate for the weakness and improve the efficiency of reinforcement of steel fibres. An attempt was made in this paper to take all the advantages mentioned above by using hybrid aligned steel fibres and PP fibres to reinforce cement-based composites. In this way, the disadvantages of steel fibre and PP fibre are avoided. Firstly, the effect of PP fibres on the alignment of steel fibres in cement-based composites was analyzed and the approach of preparation of hybrid aligned steel fibres with PP fibres reinforced cement-based composites was obtained. Secondly, the reinforcement of hybrid aligned steel fibres with PP fibres on the mechanical properties of cement-based composites was analyzed by flexural tests. Finally, the hybrid effect and mechanism of hybrid fibre reinforced cement-based composites were analyzed. The results showed that the flexural properties of hybrid aligned steel fibre with PP fibre reinforced cement-based composites were significantly higher than that of using only steel or PP fibres. •Effect of PP fibers on the aligning of steel fibers in cement-based composites is analyzed.•Hybrid mechanism of enhancing anchorage of hooked-end steel fibers by hybrid PP fibers is proposed.•Steel fibers are successfully aligned in fresh mixture with steel and PP hybrid fibers.•Hybrid effect of PP and aligned steel fibers is proved by flexural test.