EFFECTS OF PARTICLE SIZE AND MOLD SIZE ON DENSITY

The main objective of this study was to determine if variations of particle size and mold volumes affected the degree of density that would be obtained using the same energy input. Five different series of compaction tests were run on different gradations of materials with most of the testing being done on weathered shale and unweathered, dense blue shale. Conclusions in regard to compactive efforts, particle size and mold volume were as follows: (1) the degree of compactive effort and percentage of compaction moisture have a direct bearing on the percentage of swell; (2) the degree of weathering in a plastic soil has an effect on the percentage of swell; (3) oversize rock particles of a granular material must be replaced with finer rock of equal weight to produce proper density in pounds per cubic foot of material; (4) densities of natural fine grained soils are not affected by mold volume; (5) weathered shale has only a slightly higher density when a maximum 3-inch size of material is compacted in a 10-inch mold than when the standard 4-inch or 6-inch molds are used; and (6) dense blue shale will compact one to three percentage points higher when a 10-inch mold is used and the particle size is 3-inch maximum, compared to a 4-inch mold and a minus 4 sieve size particle. The above conclusions indicated that the densities obtained using the AASHO T-99 method are 1 to 3 percent less than actual densities depending on the type of shale being compacted, and that other types of soil do not appear to be affected. While the large 10-inch mold was slightly more accurate, its use was felt to be warranted only in determining exact density of blocky materials in controversial cases.

• Corporate Authors:

  South Dakota Department of Transportation

  Division of Highways, Transportation Building
  Pierre, SD  United States  57501
• Authors:
  • McDonald, E B
• Publication Date: 1971-6

Media Info

• Features: Figures;
• Pagination: 34 p.

Subject/Index Terms

• TRT Terms: Accuracy; Density; Fine grained soils; Forming; Measurement; Shale; Size; Soil compaction test; Swelling index; Swelling soils; Volume; Weathering
• Uncontrolled Terms: Particle size distribution
• Old TRIS Terms: Compaction tests; Density measurement; Fine grained plastic soils; Molds (Forming)
• Subject Areas: Geotechnology; Highways;

Filing Info

• Accession Number: 00080531
• Record Type: Publication
• Report/Paper Numbers: Final Rpt.
• Files: TRIS, STATEDOT
• Created Date: Feb 27 1975 12:00AM