Microwave heating properties of steel slag asphalt mixture using a coupled electromagnetic and heat transfer model

Abstract

Microwave heating technique is a promising asphalt pavement maintenance method with minimal external intervention. In order to employ this technology in real engineering applications, massive research efforts have dealt with avoiding overheating and non-uniform heating issues. Microwave heating frequency and power are two relevant inputs which deserve a thorough investigation. Coupled electro-magneto-thermal modeling of microwave heating is an innovative tool to understand the system performance. In this study, numerical simulations are performed to investigate the effect of the mentioned parameters on the electromagnetic and thermal fields developed inside steel slag asphalt specimens. Results illustrate that microwave heating is highly sensitive to frequency. 2.45 GHz is the optimal frequency ensuring the most uniformly distributed electromagnetic and thermal fields, and can achieve the maximum energy efficiency; furthermore, a larger input power contributes to higher temperature and better microwave healing performance. In addition, numerical simulations are compared with experimental findings for the frequency equal to 2.45 GHz and for these power values: 120 W, 280 W, 460 W and 700 W. The research characterizes the mechanism of microwave heating process and documents a good agreement between numerical and experimental findings. Furthermore, the investigation identifies the electromagnetic and thermal fields induced in asphalt mixtures and thereby contributes to optimize the microwave applicators.