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600451-00111-1 Report Abstract

Use of Infrared Thermography to Detect Thermal Segregation in Asphalt Overlay and Reflective Cracking Potential

Mostafa A. Elseifi and Nirmal Dhakal, March 2015

The objectives of this study were to assess whether temperature differentials measured using Infrared Thermography (IRT) occur in an overlay built on top of discontinuities such as joints and cracks and to study the horizontal and vertical thermal profiles in the asphalt overlay using a validated Finite Element (FE) modeling approach. To achieve this objective, an infrared camera was used to monitor the temperature profiles in the asphalt mat in a number of field projects from the time it was placed to after completion of the compaction process. The temperature profiles were monitored on top and away of severe discontinuities and joints in the existing pavement. Results showed that thermal measurements on top of the joints were consistently lower than away from it, which may indicate that temperature loss may occur at the joints. Further, a validated FE model predicted a slightly higher rate of thermal loss at the bottom of the overlay above the joint than away from it due to convection losses at the joint. While this difference may not be large enough to be identified as thermal segregation, it can influence the bulk properties of the overlay at the joints and promote early cracking. Thermal differences were also observed in the vertical direction as lower temperatures were predicted at the top and the bottom of the overlay during construction due to convection losses with the ambient atmosphere and conduction between the hot overlay and the existing pavement.

Keywords: Infrared Thermography, Temperature Segregation, Finite Element

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