Experimental Investigation on Fire Response of Steel Plate with Ultrathin Intumescent Coatings

Based on the experimental method, the fire behaviors of steel plate, whose one side is painted with intumescent coatings and the other side is adiabatic, under the pan fire of different areas, has been studied. Then the fire-resistant performance of intumescent coatings exposed to frre is explored. In the test, the factors of the initial thickness of coatings (lmm, 2 mm, 3 mm and 4 mm) and the size of oil pan (lOOmmx 1OOmm and 300mmx300 mm) are considered, and the expansion thickness of the coatings and the temperature of steel plate are obtained. The experimental results show that the intumescent coatings, which are widely applied in the market in China, tested in the experiments begin to expand when the temperature of fire gas near the surface of fireproof coating (TFGF) attains approximately 150·c, while it cannot completely expand when TFGF is lower than 45o·c. And the expansion thickness can be up to 63 mm when the frreproof coatings initial thickness is 2 mm and TFGF attains 700 ·c. Based on the observation in the experiment, it can be seen that the ultrathin intumescent coatings appeared delamination and some part of it occurred carbonization, what is more, the intumesced char layer then fell off at elevated temperature. When the initial thickness of the coatings is beyond 2 mm, the maximum temperature difference between the bare steel plate(BSP) and steel plate protected by the ultrathin intumescent coatings(SPUIC) reaches about 200 ·c, which indicates that the intumescent coatings is feasible and effective. The data obtained, are expected to be helpful to verify the fire resistant theory of intumescent coatings for steel structure further.