OPTIMIZING ASPHALT MIXTURES TO BE HEATED BY MICROWAVE

Abstract

Over the last ten years the concept of self healing in asphalt mixtures for roads pavements has been reaching great importance due to the fact that this capability allows a material to recuperate original properties after failure. This new generation of asphalt paving materials would allow road agencies to save no renewable resources as aggregates and bitumen, making the road investments more efficient. By the moment, there are two mechanisms to promote self healing in asphalt pavement: the incorporation in the asphalt mixtures of capsules containing a rejuvenating agent, or the heating of the pavement, especially the surface layer, to melt the asphalt binder, that gets liquid and refills the cracks in the material, recuperating a part of its initial structural parameters. Probably the most promising method for the in situ heating of the pavements is the radiation by microwaves. Unfortunately, asphalt mixture components (aggregates and binder) are low sensitive to microwave energy. This is why it may be advantageous to incorporate in the mixture additives to improve the sensibility to the radiation with microwaves. In this investigation two additives were studied: graphene and EAF slag coming from the steel industry. These additives were incorporated at several contents and the efficiency of the heating process was evaluated by the ratio kwh/kg/ºC in order to optimize the content of the additive in the asphalt mixture. Additionally, an evaluation of the electrical conductivity of the asphalt mixture at different contents of additives was carried out to study the possible relation between the conductivity of the mixture and its sensibility to microwave radiation. As a result of the investigation, it seems that microwave radiation can be a real option to promote in situ self healing of asphalt pavements. References J. Gallego, M.A. del Val, V. Contreras, A. Páez. Use of additives to improve the capacity of bituminous mixtures to be heated by means of microwaves, Materiales de Construcción. Vol. 67, Issue 325, January–March 2017, e110. http://dx.doi.org/10.3989/mc.2017.00416 …