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

Abstract

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.