4 - Characterization of asphalt materials by scanning probe microscopy

Abstract

This chapter discusses the utilization of scanning probe microscopy (SPM) in asphalt materials' characterization. A comprehensive introduction provides a review of the current literature in regard to both imaging techniques and nanomechanical techniques to probe mechanical properties of bituminous materials at micron and submicron scale. The second section discusses sample preparation techniques, comparing and contrasting heat-casting versus solvent (spin) casting methodologies. The advantages and disadvantages of each method are discussed and compared as to best practices for a given application. The third section focuses on the utilization of atomic force microscopy (AFM) imaging as a function of temperature and film thickness to characterize the surface freezing phenomena of paraffin wax in bituminous asphalt binders. The fourth section considers nanomechanical techniques, specifically force–displacement AFM as a method to study the adhesive and viscoelastic nature of bitumen adhesion at micron scale. This methodology is utilized to quantify transition temperature associated with mechanical fatigue. The fifth section concludes with a discussion of future trends in SPM characterization of bituminous asphalt binders. The trends that are considered include advanced nanorheology, nano-infrared spectroscopic, and scanning thermal microscopy approaches.