Mechanical properties of ultra-high-performance fiber-reinforced concrete at cryogenic temperatures

•The compressive strengths of NC and UHPFRC increase at cryogenic temperature.•Tensile strength of NC does not increase at cryogenic temperature but rather is deteriorated after exposure to cryogenic temperature.•Tensile strength, post-cracking stiffness, and energy absorption capacity of UHPFRC are improved at cryogenic temperature.•Application of UHPFRC for liquefied natural gas storage tank is appropriate. This paper aims to investigate the influence of exposure to cryogenic temperatures using liquid nitrogen on the mechanical properties of normal concrete (NC) and ultra-high-performance fiber-reinforced concrete (UHPFRC), which is commercially available. This research was carried out to examine the feasibility of using UHPFRC for a liquefied natural gas storage tank. For this, both compressive and direct tensile tests were performed at three different testing conditions: ambient temperature, cryogenic temperature (−170°C), and recovered ambient temperature after experiencing the cryogenic temperature. The test results showed that the compressive strengths of both NC and UHPFRC were noticeably increased at the cryogenic temperature compared with those at ambient temperature. However, there was no improvement in the tensile strength of NC at the cryogenic temperature, and its tensile strength was deteriorated after exposure to the cryogenic temperature. In contrast with NC, the tensile performance of UHPFRC significantly increased, including improvements in strength, post-cracking stiffness, and energy absorption capacity. Given the superior mechanical properties, it was concluded that UHPFRC is suitable for liquefied natural gas storage tanks.