A simple model to define induction heating in asphalt mastic

It is well known that mastic is a self-healing material and that its self-healing rates are highly influenced by temperature. In [1] it was shown that it is possible to make mastic conductive and to induction-heat it. Additionally, in [2] it was shown that activation energy can be used to calculate the healing times of asphalt mastic through the Arrhenius equation. If the increase of temperature with time could be predicted, the necessary induction heating time to obtain a complete recovery can be calculated. But temperature rise in asphalt mastic through induction heating, depends on a variety of parameters such as ambient temperature, output current and material resistance. For this reason, this paper presents a simple equivalent circuit to represent the thermal heat flow equations for conductive mastic, heated though induction energy. A set of differential equations is derived to calculate the equilibrium temperatures in the mastic surface. Moreover, the model parameters have been derived through the least square method for one induction-heated mixture, which temperature was measured with an infrared camera. Finally, the main induction heating mechanisms in asphalt mastic have been identified and visualized in a foil of fibers and bitumen, which temperature has been increased though induction heating and the results have been compared to those shown in [1]. (C) 2011 Elsevier Ltd. All rights reserved.