The colloidal structure of bitumen: Consequences on the rheology and on the mechanisms of bitumen modification

https://arpi.unipi.it/bitstream/11568/798598/2/polacco%20798598.pdf

A review of the fundamentals of polymer-modified asphalts: Asphalt/polymer interactions and principles of compatibility

Influence of aging on the evolution of structure, morphology and rheology of base and SBS modified bitumen

Bitumen in colloid science: a chemical, structural and rheological approach

Summary Bitumen is a complex mixture of hydrocarbons for which microstructural knowledge is incomplete. In an effort to detail this microstructure, 13 bitumens were analysed by phase-detection atomic force microscopy. Based on morphology, the bitumens could be classified into three distinct groups. One group showed fine domains down to 0.1 microm, another showed domains of about 1 microm, and a third group showed up to four different domains or phases of different sizes and shapes. No correlation was found between the atomic force microscopy morphology and the composition based on asphaltenes, polar aromatics, naphthene aromatics and saturates. A high correlation was found between the area of the 'bee-like' structures and the vanadium and nickel content in bitumen, and between the atomic force microscopy groups and the average size of molecular planes made of fused aromatics. The morphology and the molecular arrangements in bitumen thus appear to be partly governed by the molecular planes and the polarity defined by metallic cations.

/pdf/bitumen-morphologies-by-phase-detection-atomic-force-1876erlp7e.pdf

Bitumen morphologies by phase-detection atomic force microscopy.

Observations made using AFM and SEM have been combined in order to study the structure of asphalts. Fluorescence microscopy was used to aid in understanding the structural changes occurring when polymer is added to the asphalts.  With the atomic force microscope we are able to study the structure of the asphalts without any pre-preparation. Despite very low resolution, our study reveal ed a network of asphaltene molecules with regard to asphalt gel. The same result is obtained by SEM observation but with a much better resolution. SEM observation, however, needs an adequate preparation method.  In the presence of polymer we observed a rearrangement of the initial asphaltene association which leads to the assumption that polymer can aggregate the asphaltene phase.

J. Morel

Papers

New direct observations of asphalts and asphalt binders by scanning electron microscopy and atomic force microscopy

Bitumen in colloid science: a chemical, structural and rheological approach