Effect of Mass Loss of Organic Fiber on the Water Vapor Pressure and Moisture Migration of 150 and 200 MPa Ultra-High Strength Concrete Exposed to High Temperature

Abstract

In this study, 150 and 200 MPa ultrahigh-strength concrete (UHSC) specimens were mixed with polypropylene and nylon fibers and heated according to the ISO 834 heating curve. The effects of mass loss of each organic fiber on moisture migration and water vapor pressure reduction in concrete were assessed. Spalling was controlled when 0.15 to 0.25 vol% fiber was added to the specimens. The mass loss of the organic fibers effect on the pore network formation in UHSC. The nylon fiber formed pores below melting temperature via drying and allowed for moisture movement, whereas the propylene fiber effectively reduced the vapor pressure because of rapid mass loss above the melting temperature.