Research on the impact response and model of hybrid basalt-macro synthetic polypropylene fiber reinforced concrete

This paper experimentally studied the impact behavior of hybrid basalt-macro synthetic polypropylene fiber reinforced concrete under impact loads (101–102 /s) with a split Hopkinson pressure bar (SHPB) device. The fiber content of basalt fiber (BF) was 0.05%, 0.075% and 0.1% and that of macro synthetic polypropylene fiber (SF) was 0.15%, 0.25%, 0.35% and 0.5%. Both static and impact tests were conducted to investigate the effect of strain rate and fiber hybrid ratio on the dynamic performance of the hybrid FRC, i.e. impact strength, dynamic increase factor (DIF), impact strain and toughness. The test results indicate that the hybrid FRC is strain-rate sensitive and a proper fiber hybrid ratio can improve the impact performance of concrete. DIF and l g e are linearly related, whereas the impact strain, toughness and strain rate present quadratic polynomial relationship. Both BF and SF can enhance the impact strength of concrete. However, BF has a better enhancement effect than SF in terms of improving impact strength but not as good as SF in improving impact toughness. Also, appropriate BF and SF hybrid ratio can enhance the impact strength and toughness of concrete but excess fiber content has a weakening effect. In this study, the optimal fiber hybrid ratio was 0.075%–0.35% (BF-SF) which had the best impact resistance. Finally, a damage dynamic constitutive model suitable for the hybrid FRC was proposed to fit the test curves from SHPB test based on Zhu-Wang-Tang (ZWT) constitutive model.