(c) Thermal movements during
tests
Concrete panels expand when heated,
so joints tend to close as the temperature rises. A 4-ft wide concrete panel
will expand 0.1 to 0.3 in. in width during a 2-hr fire test thus reducing the
joint width significantly. (Wider panels will expand proportionally more.)
In this series of tests, the joint widths
were kept essentially constant throughout the fire tests, creating a more severe condition than would normally exist with wider panels.