Integrated approach for analyzing thermal effects on pavement construction-induced cracks

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For 80 years, the problem of transverse surface cracking of asphalt pavements has been recognized as one of the major dilemmas facing highway engineers. Extensive research has been performed that produced large volumes of literature, and predictive models. Transverse cracks are traditionally explained through thermal cracking models which may be either empirically or mechanistically based. However, both approaches fail to adequately explain the appearance of these cracks due to serious limitations in their applications. In this proposal the problem will be considered in terms of the following elements: (1) Construction induced cracks causing the surface defects necessary to initiate transverse cracking (2) The importance of bond strength on the process of cracking (3) Stress generated by changes in temperature and the response of the defected asphalt material. The proposed methodology is to model the asphalt structure after construction with surface cracks resulting from the compaction process. A Finite element method will be utilized to simulate the effects of dropping air and pavement temperatures on the stress-strain state of the cracked structure. Different scenarios will be examined including different properties, bond values, rate of change of temperature and distribution and characteristics of the construction induced cracks. The results of the analytical phase will be used to develop a laboratory technique that accurately simulates field conditions when the pavement is subjected to changing temperatures. The laboratory model will generate stresses and strains caused by the changing temperatures and not the currently simulated conditions which induce mechanically generated stresses on thermally treated asphalt materials. This research will have a significant impact on the fundamental basis treating the phenomenon of thermal cracking in particular. Great economic savings on the initial investments and maintenance and rehabilitation costs will be realized, in addition to improved travel time, road safety and restoring the public confidence in the pavement industry.