Abstract: In order to explore the safety of carbon fiber reinforced concrete under dynamic load, the longitudinal wave velocity of carbon fiber reinforced concrete specimens with different content was measured by non-metallic ultrasonic detector, and scanning electron microscopy was used to observe the bonding method between carbon fiber and concrete. The 74 mm diameter variable cross-section separated Hopkinson pressure bar test device was used to perform impact compression tests on four concrete specimens with different carbon fiber content at different strain rates, and analyze their stress-strain curves, peak stress, ultimate strain and DIF (dynamic intensity enhancement factor) change law. The results show that as the content of carbon fiber increases, the longitudinal wave speed of the specimen increases, and the carbon fiber can form a spatial network structure inside the concrete specimen to enhance the integrity of the specimen. With the same carbon fiber content, the peak stress, ultimate strain and DIF of the specimen increase with the increase of the strain rate, and the specimen has an obvious strain rate effect. Under the same strain rate, as the content of carbon fiber increases, the peak stress of the specimen first increases and then tends to a fixed value, and the two show a good quadratic function relationship. The DIF increases, the ultimate strain decreases, and the two show a linear relationship. The strength and integrity of the concrete specimens with carbon fiber are significantly improved.

Key words: carbon fiber, SHPB, longitudinal wave velocity, concrete, dynamic mechanical properties, composites