The use of passive protection materials is one of the measures normally adopted to
prescribe structural fire resistance, which intumescent coatings represents about one third
of steel fire protection costs and is growing mainly due to their use in off-site
applications.
The fire resistance of an insulated steel member is determined by assessing the
loadbearing capacity of the component during fire exposure. Heat transfer analysis of the
insulated steel member is of great importance for determining, accurately, the critical
temperature of the protected structural element, which depends essentially on the
protection material properties and on the bulk fire temperature. The specification of the
minimum protection thickness is, normally, recommended by manufactures. These values
are based on experimental fire tests, using typical structural elements (beams and
columns), being the reports kept confidential.
The intumescent coating behaviour is characterized by expansion and mass loss,
producing a foam char with a volume that varies from 5 to 200 times its original volume.
The knowledge of the coating behaviour during a fire is fundamental when this thermal
protection is applied.
This presentation will address a set of full-scale experimental fire resistance tests to
determine the behaviour of steel beams protected with intumescent coatings, considering
different dry film thicknesses.
Also a set of specimens experiments are presented and compared with a numerical study
based on steel plates coated with intumescent paint and subjected to a radiant heat flux
inside a cone calorimeter in well-controlled conditions. The intumescence thickness and
steel temperatures are measured experimentally and used in the non linear inverse
numerical analysis to assess the intumescence surface temperature and the effective
thermal conductivity
