Comparative analysis of dynamic constitutive response of hybrid fibre-reinforced concrete with different matrix strengths

In this study, the dynamic compressive behaviour of concrete reinforced with hybrid basalt-polypropylene fibres (HBPRC) and different matrix strengths was investigated using a split Hopkinson pressure bar. The results indicated that the differences between the highest dynamic strength and the dynamic strength of the reference concrete for each matrix strength grade increased from 6.63 MPa, 3.77 MPa, and 4.80 MPa under the minimum strain rates to 7.16 MPa, 9.04 MPa, and 12.08 MPa under the maximum strain rates. The strain rate effect of dynamic compressive strength of HBPRC was increased by increasing the volume of hybrid basalt fibre (BF) and polypropylene fibre (PF) from 0.1% to 0.2%, but was decreased with increasing matrix strength. The toughness was increased with increasing strain rate, hybrid BF and PF volume, and matrix strength. A microscopic test indicated that an increase in the matrix strength and strain rate exhibited a similar impact on the damage patterns of BF and PF. The primary effect of BF on the dynamic mechanical properties of HBPRC was to increase the strength and that of the PF was to improve the energy dissipation. A dynamic damage constitutive model for HBPRC was established based on the continuum media and statistical damage theories, and its validity was verified.

Automated summary

The study found that increasing the volume of hybrid fibers in concrete can enhance the strain rate effect of dynamic compressive strength, but this effect decreases with higher matrix strength. Toughness increases with higher strain rates, volume of hybrid fibers, and matrix strength.