Gypsum
board, commonly known as drywall, is normally used in buildings.
It not only gives a nice finish, but is also a fire barrier. In
case of fire, it would provide time for people to escape and for
fire fighter to put out the fire. Unfortunately, it has been used
by prescription, not by calculation, due to lack of knowledge
about the engineering mechanical properties of drywall. As a result,
no one is sure that drywall is used in the right amount. This
research involves studying the properties of drywall in high temperatures
in order to perdict the failure of drywall.
The goal of this research is to predict when and where the first
crack of drywall is going to occur in standard fire test, E119.
The first crack is important because other researchs have indicated
that wood structures collapse shortly after drywall fell off from
wood. If the failing time of gypsum could be precisely calculated,
we could increase safety and use drywall more effectively. There
are two main parts in this research: small scale testing and medium
scale testing. In the small scale testing, drywall was cut in
to small specimens such as 2"x3" and 2"x7 ½",
and tested in a small oven that can heat up to 400°C. The
properties of drywall at high temperatures will be used in calculations
to predict failure and the results will be compared to results
from the medium scale tests. In the medium scale tests, the specimen
is about 4' by 6', which is made from three pieces of 2x4 lumber
attached to 5/8" drywall with gypsum screws. It was burned
in a big oven with the standard fire that goes up to about 800°C.
The first crack was observed at about 20 minutes, and shortly
after, the oven had to be shut off because fire had engulfed the
specimen.
Percise
calculation of drywall instead of prescription would provide more
fire safety and use material more efficiently. Drywall properties
at high temperatures needed for calculations were obtained in
the small scale testing. The medium scale testing was performed
in order to compare with the results from the calculations.
