Binder design for asphalt mixes with reduced temperature: EVA modified bitumen and its emulsions

Abstract

High energy consumption and environmental risks are both associated to the use of hot asphalt mixes. In response to the need of more sustainable pavements, the modification of bitumen with low melting point EVA copolymers is investigated. Firstly, different modified binders containing EVA with varying VA contents (and so different crystalline fractions and melting temperatures) and Melt Flow Index (MFI) values were investigated. In the second stage, emulsification was implemented, in which the above EVA modified bitumen was suspended in the form of micro-size droplets in aqueous phase, in the presence of a surfactant. The results suggest that an optimum balance between VA content and MFI value will improve the binder rheological performance at medium-high in-service temperatures as well as its workability, and will facilitate its emulsification. Additionally, the binder viscosity is tremendously reduced after its emulsification, which allows mixing to be performed at much lower temperature, so reducing both energy consumption and environmental risks.