DIFFERENCES BETWEEN PETROLEUM ASPHALT, COAL-TAR PITCH AND ROAD TAR

Abstract

Petroleum derived asphalts and coal-tar pitches are often considered synonymously for the following two reasons: both materials appear similar: black or brown-black thermoplastic substances of relatively high viscosity at ambient temperatures; and both are used for similar or parallel type applications, such as roofing, paving, as protective coatings and for a number of other industrial applications. There are, however, many dissimilarities between these two materials. This report attempts to bring out a better understanding of the differences involved. To accomplish that, a review of generally accepted definitions and terms relating to both types of materials as reported in the literature is provided. Differences in origin, processes of manufacture, physical properties and chemical compositions are then described and discussed.