Observations on the Constitution and Characterization of Paving Asphalts

This paper contains results of analyses with asphalts of various composition and derivation. The objective of the study is to define and correlate constitution and fundamental character of asphalts in a manner significant to their use in highway pavements. Further confirmation of the existence of three discrete solubility fractions in asphalts was obtained by extraction methods and by paper partition chromatography. Paraffin bodies were revealed by microscopic examination of thin films. Asphaltene fractions showed the presence of particulate material by electron microscopy and also revealed indications of peptized asphaltene bodies. Oils dialyzed from asphalt exhibited u.v. fluorescence similar to components of the oil fractions obtained by extraction. Oven tests revealed increases in asphaltenes and resin fractions and attendant hardening of the asphalt. It is suggested that proper interpretation of asphalt composition is contingent upon adequate means for measuring the fundamental shearing characteristics and other rheological properties of the composite asphalt