Browsing by Author "Akkari, Alexandra Kamilla"

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    Thermal diffusivity and freeze thaw behavior of pervious concrete pavements
    (2014-12) Akkari, Alexandra Kamilla
    Past research has found that pervious concrete pavement may have significantly different thermal behavior than comparable impervious concrete pavements, which may lead to differences in important physical characteristics such as freeze-thaw behavior. This research analyzes in-situ temperature data collected from multiple pervious and impervious concrete pavement test sections over a four-and-a-half-year period. Objectives include determining in-situ thermal diffusivity of pervious concrete pavements, changes in thermal diffusivity over time due to deterioration and maintenance events, and frequency of freeze-thaw cycles in pervious concrete pavements compared to impervious concrete pavement. Research results were achieved through the development of multiple programs written for MATLAB. The first program performs an optimization routine to solve for thermal diffusivity, utilizing the heat equation to fit a temperature gradient to the raw data. This program was validated using synthetic data. A second program was developed to perform an uncertainty analysis on the thermal diffusivity results. The final portion of this research applied two previously developed methods for counting freeze thaw cycles, the 0°C Method and the Max/Min method.The analysis shows that pervious concrete pavements have a significantly lower in-situ thermal diffusivity than comparable impervious concrete pavements. The fitted thermal diffusivity of impervious concrete was consistent with those found in laboratory studies. Results showed notable seasonal trends in the thermal diffusivity results. There was no observed change in thermal diffusivity following a limited number of maintenance events. The uncertainty analysis found the standard deviation of errors and standard deviation of thermal diffusivity to be significantly low, supporting the validity of the model and the fitted thermal diffusivities. The 0°C Method showed reduced freeze-thaw cycles in the pervious concrete pavements compared to the impervious concrete pavement. However, the Max/Min method resulted in an almost equal number of cycles for both pavement types. Therefore, further analysis of pervious concrete pavements using new methods for detecting freeze thaw cycles would be beneficial.