STP1451: On the Kinetics of Thermal Loads for Accelerated Aging

    Shiao, ML
    Principal Research Engineer, Certain Teed Corp., Blue Bell, PA

    Nester, DA
    Principal Chemist and Director of Technical Service, Certain Teed Corp., Blue Bell, PA

    Terrenzio, LA
    Principal Chemist and Director of Technical Service, Certain Teed Corp., Blue Bell, PA

    Pages: 17    Published: Jan 2003


    Abstract

    A mathematical model based upon the theory of total cumulative damage has been developed to describe the kinetics of thermal aging in roofing material subjected to changing temperatures and durations. The new model employs a degradation rate function that is derived from a chemical model using a diffusion theory coupled with Arrhenius rate function to describe the temperature dependency of asphalt chemical composition under transient conditions. Such a model enables the construction of master curves in asphalt composition as aged at various temperatures, and may be used to predict the change in property due to heat aging using known roof temperature profile and materials parameters obtained from lab accelerated testing. Examples of the model are demonstrated by using the real-time roof temperature data collected from test houses located in a cold climate of Minnesota and in a hot climate of Florida. The calculations suggest that the high thermal history in a hot climate has a strong effect in accelerating aging of asphalt, particularly during the winter months. Furthermore, the effect of attic ventilation is found to reduce the uneven distribution of total cumulative damage across the roof deck due to unbalanced thermal history found in an unventilated deck. The potential application of the model and its advantage in predicting field properties by simulation are also discussed.

    Keywords:

    aging, kinetics, asphalt, shingle, cumulative damage, thermal load, ventilation, accelerated test, temperature effect


    Paper ID: STP11454S

    Committee/Subcommittee: D08.20

    DOI: 10.1520/STP11454S


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