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Pavement structures often fail due to insufficient interphase interaction between bituminous binder and mineral aggregate. A thin bituminous film covering aggregate particles is often replaced by water, resulting in bitumen-water-aggregate system, which is firmly linked to adhesion failure between these materials. This paper describes how to avoid this phenomenon using nanomaterial based admixtures – adhesion promoters maximizing the formation of intermolecular interactions between bitumen and aggregate surfaces. Physicochemical and topological principles about interaction between the two materials were described. Regular paving grade bitumen 50/70 was modified by additives based on: (i) alkylsilanes; (ii) phosphorus compounds; and (iii) amines. Mineral aggregate grains (maximal size of 16 mm, pre-heated on 160±5 °C) were covered by the thin film of reference and such modified binders (170±5 °C). In this way prepared samples were exposed to water (60 °C) for 60 minutes. After samples removing from water, their digital images were obtained and then an area of aggregate grains covered by the bituminous thin film was assessed using: (i) bitumen adhesion test; following relevant technical standards; (ii) digital image analysis based on both gray level thresholding and entropy-based segmentation. It was shown that adhesion of the bitumen to aggregate, expressed by aggregate particle coating area, was increased by almost 18 %, if adhesion promoters were used.
Keywords: Asphalt mixture, adhesion promoters, interface interaction, coated area© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.