Author(s):
R.N. Traxler
Publication Date
October 1962
Abstract
The objective of the research presented in this report was to investigate paving asphalts used by THD to determine how they can be evaluated for quality. Increases in hardness of asphalt films caused by oxidation, photooxidation, volatilization, photochemical action, and polymerization were determined by the microfilm technique. Relative viscosities were evaluated on asphalts extracted after two years of service. Hardening caused by hot mixing, transportation, and laying on the pavements was determined. Conclusions drawn from the research were: (1) Oxidation in the dark is a very important factor contributing to the hardening of films in an asphalt pavement; (2) Photooxidation probably is of secondary importance followed by volatilization; (3) Photochemical action and polymerization are of minor importance; (4) All effects are accentuated by increases in time and temperature; (5) Asphalts recovered from pavements after two years usually are quite hard because of the effect of asphalt composition, nature of the aggregate, and design and constructional factors; (6) Asphalts increase in viscosity considerably during hot mixing, transport to paving site, and laying of the pavement; and (7) Laboratory oxidation tests give valuable information concerning the potential hardening of asphalt during construction and service life of a pavement . It was recommended that the Texas Highway Laboratories be equipped with an Hallikainen Viscometer and auxiliary equipment in order that oxidation tests on 15-micron films of asphalt can be made using essentially the technique being tentatively considered by A S. T. M.
Report Number:
9-4
Link(s):
Document/Product
http://tti.tamu.edu/documents/9-4.pdf
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