Experimental impact analysis on ultra-high performance concrete (UHPC) for achieving stress equilibrium (SE) and constant strain rate (CSR) in Split Hopkinson pressure bar (SHPB) using pulse shaping technique

•Investigating compressive behavior of UHPC (200MPa) under high strain rates.•Using and tailoring pulse shaping to achieve satisfying constant strain rate and stress equilibrium.•Providing a quantitative constant strain rate factor.•Using high speed camera and digital image correlation to complement conventional strain rate measurements via strain gages. This work emphasizes obtaining and validating experimental test results of ultra-high performance concrete (UHPC) under compressive impact loading at high strain rates (30–200S−1). Cylindrical specimens of 9.2mm in height and 23.8mm in diameter were used for compression tests under dynamic and static conditions. Quality of stress equilibrium and constant strain rate were investigated using pulse shapers made of Copper and Aluminum with various geometries. Digital image correlation (DIC) was used to monitor the strains of some samples using a high speed camera at 186,000 frames per second and thus to compliment the calculated strain values obtained by the split Hopkinson pressure bar (SHBP) equations. The results showed that nearly constant strain rate and dynamic stress equilibrium over an effective duration of the test can be achieved for UHPC with a compressive strength of about 200MPa. This validated the experimental test setup and allowed for the determination of the UHPC’s dynamic impact factor based on the results obtained.