Experimental Tests on Intumescent Coating for Protecting Steel Structures

Abstract

Intumescent coatings (IC) are fireproof materials that provide the thermal insulation of steel structures. When exposed to fire, IC generally expand in thickness by 15 to 30 times in a standard test, forming a thick layer of foam that protects the steel by thermally insulating it. As part of the expansion process, many coatings generate an outer ash-like char layer. Moreover, during the process the IC change their chemical, physical and also thermal properties. This work shows an ongoing experimental program that could allow to characterize the thermal properties of the IC, based on the measurements of thickness variation during the fire and highlighting the parameters which influence the thermal behavior of IC-protected steel members. The ongoing research is aimed to allow analytical or numerical modelling of steel members protected by IC through a finite element thermal analysis. This modelling could be useful for the fire designers, since it allows to take into account the presence of the IC also when the Structural Fire Safety Engineering approach (SFSE) is applied, according to the modern fire regulations. The experimental results show that (i) small thickness of IC (500 μm) do not react homogeneously for all the section factors and (ii) the equivalent thermal conductivity depends on both the initial thickness and the section factor.