SYMPOSIA PAPER Published: 01 January 1965

Effect of Moisture on the Fire Endurance of Building Elements


The effect of moisture on the performance of building elements in fire is closely related to the amount of moisture, and in turn, to the sorption characteristics of materials. High moisture content may result in spalling. The probable mechanism of moisture clog spalling is discussed, and a criterion is developed for the fractional pore saturation at which spalling can be expected (Eq 8). if spalling does not occur, the presence of moisture is beneficial for the fire endurance. An empirical equation has been found which correlates the percentage gain in fire endurance due to 1 per cent moisture with the fire endurance in the dry condition (Eq 20). A nomogram is presented to facilitate estimation of the effect of moisture on thermal fire endurance (Fig. 9). Possible utilization of the results in the field of fire endurance testing is discussed.

Author Information

Harmathy, T., Z.
National Research Council, Ottawa, Canada
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Developed by Committee: E05
Pages: 74–95
DOI: 10.1520/STP48429S
ISBN-EB: 978-0-8031-5970-9
ISBN-13: 978-0-8031-6617-2