Effect of moisture migration and water vapor pressure build-up with the heating rate on concrete spalling type

Abstract

Abstract In this study, the effect of moisture migration and water vapor pressure build-up within high-strength concrete (HSC) on its spalling property is empirically investigated at various heating rates and compressive strengths with different water-binder ratios (W/B). An experiment is conducted on concrete specimens with various W/Bs by applying two different heating rates: fast and slow heating. It is confirmed that the moisture migration and water vapor pressure within the concrete differ, depending upon the W/B and heating rate. For HSC with W/B less than 0.33, surface spalling occurs due to the formation of moisture clogs on the surfaces of the concrete specimens, under the fast heating condition. For HSC with dense microstructures, although moisture clogs are not formed at specific positions within the concrete specimens, explosive spalling occurs due to boiling liquid expanding vapor explosion (BLEVE) in the concrete pores, under the slow heating condition.