Influence of amorphous metallic fibers on spalling properties of high-strength concrete exposed to high temperature

•The spalling properties were assessed for high strength concrete containing amorphous metallic fiber.•Water vapor pressure and residual axial load of high strength concrete exposed to high temperature were evaluated.•The proper dosage of amorphous metallic fiber to prevent spalling of high strength concrete was suggested. This study examined the effect of amorphous metallic (AM) fibers on the spalling properties of high-strength concrete. Nine specimens with concrete strengths of 100 MPa and 120 MPa were evaluated with mix proportions of polypropylene (PP) fibers of 0.15% and 0.25% by concrete volume, and proportions of AM fibers of 0.3% and 0.5% by concrete volume. These specimens were then heated in accordance with the ISO-834 heating curve. The movement of water vapor through a pore network formed by molten PP fibers was found to be a dominant factor controlling the spalling of high-strength concrete. Spalling control was not found to be significantly affected by the addition of 0.3% AM fibers; however, when 0.5% AM fibers was added, cracking was limited and so were paths for water vapor migration, increasing the likelihood of a moisture clog and creating the differential internal pressure often blamed for concrete spalling.