A pilot study on microwave heating for production and recycling of road pavement materials

• Microwave heating of materials allows to reduce processing time and save energy.
• In highway engineering no real commercial microwave applications are yet developed.
• Laboratory results confirm the effectiveness of microwave for aggregate heating.
• A numerical model of microwave heating and drying is calibrated and validated.
• Results will be applied for designing a prototype of microwave heating plant.

In the last decades microwave radiation has found several applications in many industrial processes, thanks mainly to the rapid heating throughout the material thickness with reduced thermal gradients, that allow to reduce processing time and save energy. Although the operational and environmental advantages of microwave technology are well known also in the field of highway engineering, no real commercial applications are yet developed.The present paper shows the results of a pilot study that analyses microwave heating for aggregates and asphalt materials. The study is performed in laboratory, comparing data with conventional heating and using numerical simulation for calibrating and validating a model for further applications. The overall objective is to check the possibility of including the microwave heating technology in the manufacturing and recycling processes of asphalt, in order to reduce environmental and health risks with an increase of the efficiency of the whole process.Results are very promising, confirm several literature findings about the advantages of microwave heating compared to conventional heating and validate a numerical simulation model, that can be applied for designing a prototype of microwave heating plant.