Experimental exploration on impact characteristics of ultra-high performance concrete at low and cryogenic temperature

Concrete structures in polar region and liquefied gas storage system need to be designed against combined low temperature and dynamic loads. Understanding the mechanical behaviour of concrete under these extreme conditions is critical for ensuring the structural integrity and safety. This study presents an experimental investigation on the dynamic compressive and splitting tensile performance of UHPC subjected to low temperatures of -70 °C and -160 °C. The compressive and splitting tensile strengths of UHPC were examined at various strain rates (40 ∼ 160 s -1 for compression, 20 ∼ 80 s -1 for splitting tension) and temperature conditions (at 20, -70 and -160 °C) via Split Hopkinson Pressure Bar (SHPB) device. The dynamic compressive as well as splitting tensile strengths of UHPC increased significantly with rose of the strain rate. The dynamic increase factors in compression (CDIFs) decreased with the decline in temperature. The compressive strength under a strain rate of 120 s -1 at ambient temperature were approximately 1.09 and 1.16 times higher than at -70 and -160 °C, respectively. On the other hand, an opposite behaviour was observed for the dynamic increase factors in split tension (TDIFs) of UHPC, i.e., TDIFs rose as the temperature decreased. Based on the experimental data, it showed that the TDIFs at -70 and -160 °C were nearly 1.16 and 1.21 times higher than at 20 °C at the specified strain rate 60 s -1 . • SHPB tests on UHPC specimens at -70 o C and -160 o C were conducted in both compression and tension. • DIFs in compression of UHPC decreased with decline in temperature, but DIFs in tension increased when the temperature went down • Empirical formulae for DIFS in compression and tension at cryogenic temperature were proposed.