Durability evaluation of intumescent coating for steel frames

This paper reports on the results of experimental studies on the durability of intumescent coating for steel frames. Intumescent coatings are fireproo f materials that provide the thermal insulation of steel structures. They s tart to foam when the surface temperature reaches about 300 degreesC by hea ting and form a layer of carbonaceous char 25 to 50 times thicker than at r oom temperature. However, their durability dr long-term fireproofing is not clear. Preliminary accelerated tests and small-scale heat tests were condu cted, and it was found that water is the principal environmental factor tha t affects the durability of intumescent coatings. Another series of acceler ated tears and exposure tests was then performed mainly for water resistanc e. 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 prop osed for evaluating the durability of intumescent coatings by considering t he high-temperature and high-humidity weather conditions of Japan.