Compressive and tensile behaviour of concrete subjected to high rate of loading

The present study describes the dynamic tensile and compressive behaviour of concrete with respect to failure (damage) and material characteristics. The dynamic compression and tension tests were performed by using the Split Hopkinson Pressure Bar setup of 65 mm diameter of bars. The cylindrical specimen tested under dynamic loading conditions was ~ 30 mm in length with two different diameters (30 mm and 45 mm). The quasi-static compressive and splitting tensile strength of concrete was found to be 49.48 and 5.42 MPa, respectively. Dynamic testing showed a significant 78% increase in compressive strength as the strain rate increased from 1.33 × 10^–4 to 284 s⁻¹. Likewise, tensile strength increased by approximately 303.4% when the strain rate increased from 6.67 × 10^–4 to 14.95 s⁻¹, demonstrating concrete high strain rate sensitivity to dynamic tension. Under dynamic compression, the concrete strength increases due to the formation of the large number of cracks and high lateral confinement. In addition, the crushing density of concrete specimens has been increased with an increase in strain rate. During dynamic tensile failure, the specimen split into two semi-cylindrical pieces at low strain rate. Concurrently, localized crushing occurred at a high strain rate due to stress concentration at loading points. As the strain rate increased further, it intensified the localized crushing, ultimately giving rise to the formation of a wedge region followed by crushing zone.