[Zurück]

S. Nahar, A. Schmets, G. Schitter, A. Scarpas:
"Quantitative nanomechanical property mapping of bitumen micro-phases by peak-force Atomic Force Microscopy";
Vortrag: International Conference on Asphalt Pavements, Raleigh, North Carolina, USA; 01.06.2014 - 05.06.2014; in: "Asphalt Pavements", Taylor & Francis Group, (2014), ISBN: 978-1-138-02693-3; S. 1397 - 1406.

It is commonly assumed that the two-phase morphology of bituminous
materials at the micrometer length scale is the origin for the material´s mechanical response at
larger length scales. Usually this morphology, or microstructure, is observed by using Atomic
Force Microscopy (AFM), providing height and phase maps of the material´s surface. The
aim of this work is to quantify the nanomechanical properties of the phases that constitute
the microstructure of bitumen, using Peak-Force Tapping mode AFM. The mechanical
properties, i.e. modulus, probe-sample adhesion force, dissipated energy and deformation
are measured for four well defined bitumen grades from the SHRP library. It is found that
the measured mechanical property maps possess similar morphological characteristics as the
height and phase images from traditional AFM, i.e. they overlap. For all phases of the four
bitumen the averaged mechanical properties could be obtained. After proper averaging, these
properties could be compared between the four bitumen grades and with their documented
macroscale properties. Such correlations were found to exits, but also anomalies have been
found. These anomalies may originate from a different viscoelastic response of the material
phases at the experimental loading rate of 2 kHz, while traditional mechanical tests are performed
at much lower frequencies. Thus, a systematic study of the nanomechanical properties
is presented, with promising results that shall enable a better understanding of the link
between micro and macro-scale properties of bituminous materials.

bitumen, nanomechanical properties, Peak Force AFM, Derjaguin-Muller- Toporov model