Fracture and explosive spalling of concrete slabs subjected to severe fire

The paper presents an experimental investigation on explosive spalling and fracture-induced deformation of 6 full-scale simply supported reinforced concrete slabs subjected to conventional fire curve (BS476) and severe hydrocarbon fire curve, performed at the Fire Research Centre, University of Ulster, UK. Each slab was loaded with 14% of its ultimate load and was heated from the bottom side only. Temperature profile was recorded at 3 depths within the slabs and the moisture content was also measured before and after the tests. The deflection of the slabs was recorded at the middle of the 3 meters span. All slabs suffered from explosive spalling at different degrees. The study showed that explosive spalling took place much earlier and was more violent in slabs subjected to hydrocarbon curve in comparison with BS476. The paper ends with analysis of interaction between the parameters involved in the tests.