Engineering Mechanics Institute Conference 2013

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Investigation of Induction Healing Effects on Electrical Conductive Asphalt Mastic and Asphalt Concrete Beams through Fracture-Healing Tests

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Qingli dai
Michigan Technological University
United States

Zigeng Wang
Michigan Technological University
United States

Abstract:
The purpose of this research is to evaluate the healing capacity of asphalt mastic and concrete beam samples containing steel wool fibers. The induction system includes induction coil with applied alternative currents, the generated alternative magnetic field with the same frequency, the electrical conductive steel wool fibers within materials. The material sample can be heated with different heating mechanisms but a main one with Joule effects through eddy currents. During induction healing, the non-Newtonian binder flow will fill up crack space and new adhesion strength will be also built up. To investigate this healing effects, asphalt mastic and concrete beam samples were prepared by incorporating type 1 steel wool fibers, chopped to an approximate length of 6 mm. Subsequently, the mastic beams were tested with fracture-healing cycles under the three-point bending loading and induction healing. The concrete beams were also tested with fracture-healing cycles under the modified beam bending loading with an elastic foundation. Prior to the fracture tests, both samples were conditioned in the freezer for 6 hours at -20oC to limit the viscoelastic and viscoplastic deformation. The samples were loaded until the peak strength was reach. During the healing process, the specimens were heated to three different temperatures (60°C, 80°C and 100oC) within several minutes. The samples were also held for 1-2 minutes with the desired heating temperatures. From the cyclic healing-fracture test data of mastic samples, it was found that the samples can be healed with full recovery strength at the heating temperature of 60°C. The results at the heating temperatures of 80°C and 100oC showed that the trend of peak load was fluctuated around the original value. For the asphalt concrete beams, the cyclic healing-fracture test showed that the healing effect at the heating temperature of 80 oC was better than of the two other temperatures (60°C and 100oC). Another two samples were tested under the peak-to peak beam-bending loading without healing as the comparison data to evaluate the induction healing effects. The lab test data indicate that sustainable pavement materials can be developed with added conductive fibers to elongate the service life of asphalt pavements.

 

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