Influence of expanded vermiculite on fire protection of intumescent fireproof coatings for steel structures

The effects of expanded vermiculite (EV) as modified filler to improve fire protection of intumescent fireproof coatings have been studied. It was found that the fire protection and char structure of the coating was significantly improved by adding 7% EV (by mass) into the coating. The results showed that the flaky structure of EV could promote the expansion and carbonization of the coating under fire, which could reinforce the heat-insulation performance of the char layer and reduce its corrosion at high temperature. The X-ray diffraction and thermogravimetry results indicate that additional EV may increase the thermal decomposition temperature of the coating and enhance the antioxidation performance of the char layer at high temperature. However, the study also shows that the excessive amount of EV with flaky structure will lead to the nonuniform diffusion of the nonflammable gases in the melting char under fire and will depress the fire protection and expansion performance of the coating.