LAUSR

Abstract Complex Modulus (E∗) or stiffness is a fundamental design parameter of flexible pavements which can be used to determine the response of asphalt mix under traffic loading and thermal conditions. The modulus value heavily depends on the temperature of the mix as well as the speed of loading. High-modulus asphalt mix, or Enrobe a Module Eleve (EME) in French, is a type of Hot Mix Asphalt (HMA) that has high stiffness at intermediate temperature. EME has several advantages over conventional asphalt mix including reduction in layer thickness and improved structural life. The purpose of this study is to evaluate rheological behavior of EME mixes fabricated with modified asphalt binders. In this study, two types of EME mixes based on nominal maximum aggregate size (NMAS) were developed (EME 12.5 and EME 19) using three different polymer modified asphalt binders (PG 58-28 plus Elastomer additives, modified PG 82-28 and PG 88-28). Complex modulus test was conducted at five different temperatures (−10, 4, 21, 37, 54 °C) and six loading frequencies (0.1, 0.5, 1, 5, 10 and 25 Hz). 2S2P1D rheological model was used to characterize the rheological properties of EME mixes. Environmental Scanning Electron Microscope (ESEM) was used to investigate the binders’ microstructures in terms of density, fibril size and structural network along with time required for fibril formation. The obtained results showed that there was a considerable difference between the rheological properties of the mixes, and that EME 19 with PG 88-28 performed more elastically. On the other hand, complex modulus of EME mixes with PG 58-28 + Elastomers had larger viscous component. In addition, a good correlation between EME rheological properties and microstructure of the modified binders was observed as explained in this paper.