Explosive Concrete Spalling During Large-Scale Fire Resistance Test

This paper presents a comprehensive investigation of explosive heat-induced spalling observed during a set of large-scale fire resistance tests (or standard furnace tests) on prestressed concrete slabs. The study, based on data from large-scale tests, examines the influence of numerous design parameters in the occurrence of spalling (age of concrete, inclusion of polypropylene fibres, depth of the slab, and prestressing level). Furthermore, a careful thermal analysis of the tested slabs is presented; a comparison of in-depth temperature distributions inside concrete slabs shows that spalling occurred for slabs with more rapid in-depth temperature increase. The analysis presented herein shows that the scatter of in-depth temperature increase experienced by concrete slabs tested simultaneously has a substantial influence in the occurrence of heat-induced concrete spalling.