Durability Evaluation of Intumescent Coating for Steel Frames

Abstract

This paper reports on the results of experimental studies on the durability of intumescent coating for steel frames. Intumescent coatings are fireproof materials that provide the thermal insulation of steel structures. They start to foam when the surface temperature reaches about 300°C by heating and form a layer of carbonaceous char 25 to 50 times thicker than at room temperature. However, their durability or long-term fireproofing is not clear. Preliminary accelerated tests and small-scale heat tests were conducted, and it was found that water is the principal environmental factor that affects the durability of intumescent coatings. Another series of accelerated tests and exposure tests was then performed mainly for water resistance. The fire resistance of specimens after degradation was verified in full-scale heat tests. As a result of these tests, a new testing method was proposed for evaluating the durability of intumescent coatings by considering the high-temperature and high-humidity weather conditions of Japan.