decomposition,
dehydration, and loss of material [20].When the duration
of the fire exposure was reduced to 60 min (1700F or 927 C) and
30 min (1550F or 843 C), the effects on the concrete specimens
were not so detrimental. The specimens exposed to direct fire for
30 min retained integrity better than those exposed for 60 min
(based on visual inspection); the 30 min exposure results are
shown in Table 1.