An Experimental Study of the Effects of Crack and Detachment on Insulation Properties of Intumescent Coating

AbstractThis paper presents the results of an experimental study to investigate the failure modes of intumescent coatings and their effects on temperatures attained in steel sections and load carrying capacities of steel columns. Primer and intumescent coatings were applied to unloaded steel plates, unloaded I‐shaped short sections and axially loaded I‐shaped long columns. For the axially loaded columns, three different surface treatments were considered. The failure modes of intumescent coatings include distributed fine cracking, discrete wide and deep cracking, and detachment. Distributed fine cracks appeared on the unloaded plate specimens. Discrete crack was the main failure mode on the unloaded steel sections. For the loaded long columns, the intumescent coating failure modes included both discrete crack and detachment. Intumescent coating failure affected the average temperatures attained, with average temperatures of the plate specimens, unloaded steel sections and loaded steel columns being 411°C, 472°C and 543°C respectively after 30 minutes of standard fire exposure. Different surface treatment does not seem to have much effect on fire resistance of the carbon steel columns, the two columns reaching fire resistance times of 38 and 39.5 minutes respectively.