The viscoelastic behavior of bitumen (asphalt binder) is the subject of one of the world’s longest running experiments: the famous University of Queensland pitch drop experiment started in 1927. This experiment is sensitive to the bulk properties of the material, but provides no information regarding the nanostructure of the material or viscoelastic properties at the nanoscale. Other more recent experiments with Dynamic Shear Rheometer (DSR) are similarly limited.
Aljarrah et al. have now applied PeakForce QNM and AFM-nDMA to investigate the mechanical properties of bitumen at the nanoscale, with the PeakForce QNM maps allowing identification of three phases (bee structure, interstitial, and matrix) and AFM-nDMA providing co-located viscoelastic spectra. By collecting these spectra at different temperatures the team was able to construct nanoscale master curves that could then be compared to bulk DSR measurements. They found that the DSR and AFM-nDMA curves were qualitatively similar, but that the nanoscale moduli were significantly stiffer and less viscous than the bulk. The authors attribute this difference to the molecular structure of the material probed by the AFM tip as compared to the bulk and to weaknesses at the interfaces between phases in the bulk.
If you have any questions about PeakForce QNM, AFM-nDMA, or any of our other solutions for viscoelastic property characterization, please contact us. Sign up to automatically receive future Journal Club updates via email.
FEATURED BRUKER TECHNOLOGY:
AFM-nDMA, Asphalt Binder, Asphalt Rheology, Building Materials, Binder Properties, Construction Engineering, Viscoelastic Properties