Application of 915 MHz microwave in regenerative heating of asphalt pavement

Abstract:

To verify the feasibility of 915 MHz microwave frequency for regenerative heating of asphalt pavement materials, on the basis of analyzing the microwave heating mechanism, the horn antenna parameters were designed and optimized, and the heating effect of single antenna and array antenna on asphalt mixture under two microwave frequencies of 915 MHz and 2 450 MHz was compared by using CST simulation software. The influencing factors such as antenna spacing, heating height, and mixture thickness on the heating effect were simulated. Results show that the asphalt mixture heated by 915 MHz microwave frequency had better uniformity and a smaller temperature gradient in the depth direction. The variation of the antenna spacing, heating height, and mixture thickness caused changes in the microwave interference phenomenon in the heating box, which in turn affected the heating effect. Under the conditions of mixture thickness 250 mm, antenna spacing 70 mm×70 mm, and heating height 70 mm, the heating effect was the best, the average temperature of the mixture was the highest, and the discrete coefficient was the lowest, with good temperature uniformity and less asphalt aging phenomenon. For large-scale microwave regenerative heating equipment, due to the requirements for large heating thickness and high output, 915 MHz is recommended.