Effects of fibers on flexural strength of ultra-high-performance concrete subjected to cryogenic attack.

• Flexural strength and compressive strength of UHPC before and after cryogenic attack were studied. • Cryogenic damage variable of UHPC were investigated. • Fracture characteristics and micromorphology of UHPC were analyzed. As one of the most common extreme environments, cryogenic temperature will directly threaten the structural safety of normal service concrete, and engender the premature deterioration of the structure performance. In this paper, steel fiber, polypropylene fiber, and polyvinyl alcohol fiber were selected to prepared ultra-high-performance concrete (UHPC), and the effects of different fibers on flexural strength and compressive strength of UHPC subjected to cryogenic attack were investigated. The results indicated that the addition of steel fiber and PVA fiber improved the flexural strength and compressive strength of UHPC. After the cryogenic attack, the flexural strength of UHPC increased by 70.06% with the increase of length-to-diameter ratio of steel fiber, and the peak deflection increased from 0.501 mm ~ 0.919 mm to 0.609 mm ~ 1.302 mm. Conversely, the flexural strength of UHPC with PVA fiber and PP fiber decreased by 33.76% and 33.18%, respectively. The peak deflection of UHPC with PVA fiber decreased from 0.106 mm to 0.064 mm. When the length-to-diameter ratio of steel fiber was 65, UHPC reached the highest compressive strength of 173.06 MPa. The compressive strength of UHPC decreased after the cryogenic attack. PVA fiber and PP fiber absorbed a lot of water, which affected the cement hydration in UHPC, thus reducing the strength of UHPC. [ABSTRACT FROM AUTHOR]