Design of Heavy Duty Mixes

About the report:

Permanent deformation of asphalt concrete, which is frequently manifested by excessive pavement rutting, has become a problem in much of the United States. Virginia began to experience rutting problems on highways with heavy traffic in the early 1980s. The purpose of this study was to evaluate several promising test procedures that could be used to test asphalt mixes for susceptibility to rutting. Several mixes representing a range of rutting potential were tested with five test methods: resilient modulus test, indirect tensile test, compaction resistance test, compression creep test, and a test using the gyratory testing machine. The compaction resistance test did not point up differences in the tendencies of mixes to rut. The resilient modulus test, the indirect tensile test, and the compression creep test were capable of distinguishing between mixes with wide difference in rutting, but these tests failed to differentiate between the performance of mixes with questionable rutting resistance. The use of the gyratory testing machine ranked mixes prepared in the laboratory correctly and pointed up deficiencies in some field mixes that had been designed according to the 75-blow Marshall design but had demonstrated poor field performance. The report recommends that the gyratory testing machine be further evaluated as a design tool for heavy duty asphalt mixes to supplement the Marshall design.

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