SYMPOSIA PAPER Published: 01 January 1960

Progress Report on the ZACA-Wigmore Experimental Asphalt Test Project


During 1954 the California Division of Highways (CDH) introduced improved specifications for paving grade asphalts. As part of a program to determine performance under field conditions ten different asphalts were placed on a major construction project consisting of entirely new construction and an overlay over an old portland cement concrete pavement. The test sections were constructed under nearly identical procedures and have been subjected to common climatic and traffic conditions.

All of the asphalts were of the 200 to 300 penetration grade and represented different crude sources and methods of production as found in California with one exception. The exception is a mid-continent crude source asphalt produced in a refinery in Arkansas.

Of the nine California asphalts two complied with the 1954 Standard Specifications but not with the new Special Provision Specifications and seven complied with both the old and new proposed specifications, which since that date have been used by CDH for the purchase of paving grade asphalts.

Most of the asphalts were placed in 2500-ft test sections on both the new and blanket pavements. Complete field studies were carried on during construction and Abson recovery tests were made on the paving mixtures. Observation and test results confirm the fact that asphalts manufactured by different methods and from different crude sources, although placed under virtually identical conditions, exhibit varying degrees of hardening during the mixing process.

A description of tests performed on field cores during the past three years of service life is provided. These results indicate quite marked differences in the weathering rates of the various asphalts when compared under equivalent construction, traffic and climatic conditions.

Field performance evaluations of the test sections to date are provided together with a short description and analysis of the failure of three test sections.

Author Information

Hveem, FN
California Division of Highways, Sacramento, Calif.
Zube, E
California Division of Highways, Sacramento, Calif.
Skog, J
California Division of Highways, Sacramento, Calif.
Price: $25.00
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Developed by Committee: D04
Pages: 3–45
DOI: 10.1520/STP38770S
ISBN-EB: 978-0-8031-5600-5
ISBN-13: 978-0-8031-5599-2