Dynamic Characterization of Concrete using Split Hopkinson Pressure Bar

Concrete exhibits brittle behaviour and is weak under tensile and flexural loading. The response of concrete to dynamic loading is of interest in a variety of civilian and military applications. Understanding the response of concrete to impact or explosive loading is important for effective protection of defence and civil structures. The split Hopkinson pressure bar (SHPB) technique has been used widely to measure the dynamic strength enhancement of materials at high strain rates. Although, SHPB technique has been verified for metallic materials, but validity and accuracy of SHPB results for non-metallic, e.g. concrete materials have not been thoroughly studied so far. The present study examines the application of SHPB to determine the dynamic strength of concrete under compressive loading. The aim of this study is to understand the strain rate effect on the ultimate uniaxial compressive strength of concrete in SHPB tests for two different grades of concrete. The behaviour of concrete at strain rates of the order of 200 - 600 per second and pressures up to 0.38 MPa are studied experimentally. The strength of concrete is found to be increased with the increase in strain rates. Further, it is observed that due to the composite microstructure of concrete, deformation and stresses are non-uniform in the concrete specimens.