Quantitative Freezing and Thawing Parameters for Composite Roof Decks

Frost action parameters (cooling rate, freezing temperature, duration of freezing, warming rate, thawing temperature, and duration of thawing) for composite roof deck systems composed of structural concrete and asphalt-gravel surface materials, with and without insulating layers, were developed using climatic data from Chicago, Illinois. All calculations were accomplished by use of a multilayered, transient, heat-transfer model developed at the University of Illinois.

An idealized freeze-thaw cycle was established for analysis purposes. The frost action parameter data showed substantial variability as related to the effects of position in the composite section and time of year. Comparisons of the data with standard freeze-thaw testing procedures indicate that the standard procedures many times do not adequately simulate field service conditions. It is indicated that frost action parameter data, similar to those generated in this study, should be considered in the development of realistic and rational freeze-thaw durability testing procedures. From the results of this study, it would appear that testing procedures developed from quantitative freezing and thawing parameters should be used to assess the durability of composite roof deck systems.