Study of crack dynamic propagation behavior of fine-grained concrete under static loading

Under static loading, crack propagation processes are a dynamic process due to very high propagation speeds. For fine-grained concrete material under static loading, the crack propagation speed can reach 723.7 m/s, thus the crack propagation process under static loading actually can be considered as a dynamic issue, not a static issue. Crack propagations with a rapid speed are extremely unfavorable to the stability of concrete structures. Therefore, it is of significance to study the dynamic fracturing of concrete structure under static loading. Three-point bending (TPB) tests were conducted by using concrete specimens. A novel test system coupled with crack propagation gauges (CPGs) and strain gauges (SGs) was utilized to measure the crack speed and the initiation loads. The experimental results show that crack propagation velocities are not a constant and the propagation toughness of fine-grained concrete varies with the crack tip displacement. The initiation toughness is higher than the propagation toughness.