PERFORMANCE OF THREE AGGREGATES ON ALL-WEATHER ROADS - FINAL REPORT

A field study was conducted in which the performance of slate was compared to that of two other aggregates. For the study, two test sites were constructed using granite, slate, and greenstone. Prior to being placed on the road, the aggregates were tested for California Bearing Ratio (CBR), gradation, and Atterberg limits. While in service, the aggregates were sampled and tested for gradation, Atterberg limits, thickness of the layer, and skid resistance. The composition of the Arvonia slate is very high in muscovite, a flaky mineral that is particularly susceptible to winnowing and somewhat self-lubricating. The slate had a much lower CBR than either the granite or greenstone, and this value did not improve when the slate was not soaked before testing. This absence of improvement was attributed to the lubricating effect of muscovite. It was observed that the slate disintegrated at a much faster rate during the first 5 weeks of service than did the granite or greenstone. Such early wear is extremely important because, normally, very light applications of crusher run are made to all-weather surface roadways, and it is necessary that the larger sizes of aggregate maintain their integrity so they can be reused when the roadway surface is reshaped. Two changes in the specifications for crusher run and a change in policy were recommended. (Author)

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• Record URL:
  • https://rosap.ntl.bts.gov/view/dot/19101
• Corporate Authors:

  Virginia Highway and Transportation Research Council

  Charlottesville, VA  United States 

  Virginia Department of Highways

  Traffic and Planning Division, 1221 East Broad Street
  Richmond, VA  United States  23219

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Noble, D F
• Publication Date: 1985-11

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 38 p.

Subject/Index Terms

• TRT Terms: Aggregate gradation; Aggregates; Alternatives analysis; Atterberg limits; California bearing ratio; Field studies; Granite; Skid resistance; Slate; Specifications; Thickness; Wear
• Old TRIS Terms: Gradation
• Subject Areas: Geotechnology; Highways; Pavements; I36: Aggregates;

Filing Info

• Accession Number: 00453674
• Record Type: Publication
• Report/Paper Numbers: FHWA-VA-36-16, VHTRC 86-R16
• Contract Numbers: 2172-000-940
• Files: NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: Jul 31 1986 12:00AM