Experimental investigation on steel elements protected with intumescent coating

The paper presents the results of experimental tests on a commercial water-based intumescent coating (IC), aimed to investigate its thermal properties and to correlate temperature and thickness variation. The tests were performed in a furnace on IC protected steel plates with different dimensions (i.e. section factors) and IC thicknesses. The temperature in the furnace followed the ISO834 curve or the smouldering curve. The temperature was measured by means of traditional thermocouples and the expansion of the IC by means of a reading of digital metric photos. The results of the tests show that (i) small thicknesses of IC do not react homogeneously, (ii) the equivalent thermal conductivity depends on the section factor but is independent of the shape of the plate, and (iii) slightly influenced by the selected fire curve. Starting from the results of lab-scale tests, correlations between IC thermal conductivity and its influencing parameters can be calibrated, providing a useful instrument to set the IC properties in both simplified and advanced numerical models