Experimental study and theoretical analysis on dynamic mechanical properties of basalt fiber reinforced concrete

Basalt fiber reinforced concrete (BFRC) has the advantages of strong impact toughness, excellent high temperature resistance and good durability, and it has been gradually used in building structures. During the service life, a concrete structure may be subjected to high strain rate dynamic effects such as explosion, but the research on the impact performance of BFRC still warrants further effort. In order to explore the dynamic mechanical properties of BFRC under high strain rates, an experimental study was conducted on BFRC using Split Hopkinson Pressure Bar (SHPB) by considering 5 strain rates, 4 basalt fiber (BF) contents and 4 BF lengths, so as to analyze the effects of strain rate, BF content and BF length on its dynamic mechanical properties. The results showed that the increase in strain rate under the same BF condition would significantly increase the compressive failure extent and improve the compressive strength and dynamic increase factor (DIF) of BFRC. Under a constant strain rate, the compressive strength, DIF and deformability of BFRC all showed an increasing trend first followed by a decrease with the increase of either BF content or BF length. According to the static and dynamic data of comprehensive analysis, it was found that the compressive strength and DIF of BFRC reached their maximum values (88.0 MPa and 2.71, respectively) at the BF content of 0.2% and the BF length of 6 mm. The DIF was more sensitive to the BF content than to the BF length. Combined with the scanning electron microscopy (SEM) and computerized tomography (CT) technology, the action mechanism of the dynamic mechanical properties of BFRC was analyzed and revealed from a microscopic perspective. Meanwhile, considering the effect of BF reinforcement, the BFRC dynamic constitutive equation was proposed based on the Holmquist-Johnson-Cook (HJC) model and applied to numerical calculation. The results showed that the proposed constitutive model had a good applicability. The findings in this paper provide useful experimental and theoretical basis for the calculation and response analysis of BFRC structures under dynamic loads such as impact and explosion. • The tests on the dynamic performance of BFRC under impact were carried out. • The effects of strain rate, BF content and BF length on the compression properties of BFRC were analyzed. • The fiber reinforcement mechanism of BFRC was explored from microscopic perspectives. • The BFRC dynamic constitutive equation was established.