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WISCONSIN STRUCTURES & MATERIALS TESTING LABORATORY (WSMTL)

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Failure Prediction of Gypsum Board Exposed to Elevated Temperatures
Research by
Gumpon Sriprutkiat & Onesty Friday/
Prof. Steve Cramer
Dept of Civil & Environmental Engineering

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.


Photo Medium Scale TestPercise 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.

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Wisconsin Structures & Materials Testing Laboratory
University of Wisconsin-Madison
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