Comparative Evaluation of 4-Inch and 6-Inch Diameter Specimens for Testing Large Stone Asphalt Mixes

by Prithvi S. Kandhal, Auburn Univ, United States,
E. R. Brown, Auburn Univ, United States,

Document Type: Proceeding Paper

Part of: Serviceability and Durability of Construction Materials


Modified Marshall equipment and Gyratory Testing Machine (GTM) are now available for compacting and testing 6-inch diameter specimens to accommodate aggregate up to 2-inch maximum size. However, some agencies continue to use 4-inch diameter specimens for mixes containing 1 1/2 -inch maximum size aggregate. This study compares the mix properties such as Marshall stability and flow, indirect tensile strength, and permanent deformation (from static creep test) obtained on 4-inch and 6-inch diameter specimens. Both Modified Marshall and GTM equipment were used to compact the specimens of these two sizes. The test data indicates increased coefficient of variation when testing 4-inch specimens of the mix containing aggregate larger than one inch compared to 6-inch specimens. The 6-inch diameter specimens also had lower variability in creep test compared to 4-inch specimens. Additional study results are discussed.

Subject Headings: Comparative studies | Material tests | Rocks | Asphalt pavements | Aggregates | Equipment and machinery | Tensile strength | Creep

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