Uniaxial Compressive Behavior of Granite at High Strain Rates

Granite is a common construction material that is widely used in the various types of structures, but its dynamic behavior is not clearly understood. To investigate the uniaxial compressive behavior of the granite under high strain rates compression, three groups of specimens with the same aspect ratio (0.5) but different diameters were tested with two large split Hopkinson pressure bar systems with respective diameters of 60 and 155 mm. The latter allowed the large specimen with diameter up to 150 mm to be employed in the compressive tests. Brittle fracture was the main failure pattern in the dynamic tests. The fragment size decreased with the increasing strain rate, ranging from 21 to 286 s−1. The percentage of the fragments with small sizes (  20 mm) decreased. The incomplete stress–strain curves corresponded to the incomplete fragmentation of the specimens. The representative stress–strain curve of each impact velocity was developed using a mathematical model. The dynamic strength of the 50-mm- and 60-mm-diameter specimens were identical, while that of the 150-mm specimens was larger at the same strain rate level. The dynamic increase factor was   1.0 at higher strain rates. The energy absorption density increased with the impact velocity, dynamic strength, and strain rate. Two groups of representative curves were developed to describe the relationships between the energy absorption density, strain rates, and dynamic strength.