áááá Fire Resistive Properties of
Gypsum
uáá Gypsum is approximately 21 percent
by weight chemically combined water which greatly
contributes to its effectiveness as a fire resistive barrier.
uáá
When
gypsum-protected wood or steel structural
members are exposed to a fire, the chemically combined water being
released as steam acts as a thermal barrier
until this slow process, known as calcination, is
completed.á The temperature
directly behind the plane of calcination
is only slightly hotter than that of boiling water
which is significantly lower than the temperature at which
steel begins losing strength or wood ignites.