Towards a better understanding of wetting regimes at the interface asphalt/aggregate during warm-mix process of asphalt mixtures

The substrate heterogeneity degree determines asphalt wetting behavior. For a model glass substrate, only asphalt characteristics have an impact: asphalt viscosity, polarity and saturates content are influent factors. On the mineral heterogeneous substrate, asphalt viscosity and asphaltenes content have an impact on wetting indicators. Substrate heterogeneities also appear as a very important factor which improves considerably wetting quality. The tested mineral substrate has been revealed as a biphasic composite material for which the wetting regime was modeled by a Cassie-Baxter model. A comprehensive approach has been proposed to explain asphalt wetting on heterogeneous substrates in correlation with Scanning Electron Microscopy observations. This Cassie-Baxter model is essential to understand adhesion phenomena on heterogeneous road materials. It seems also to be a promising way to evaluate quality adhesion of “asphalt/RA” mixtures.