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Aggregate Subgrade Thickness Determination

File Language:
English


Details

  • Creators:
    Heckel, Greg
  • Corporate Creators:
    Illinois. Department of Transportation. District 6
  • Subject/TRT Terms:
  • Publication/ Report Number:
    IL-PRR-154
  • Resource Type:
    Tech Report
  • Geographical Coverage:
    United States
  • Edition:
    Final Report: August 2003 to August 2005
  • Corporate Publisher:
    Illinois. Department of Transportation. Bureau of Materials and Physical Research
  • Abstract:
    This study examines the Illinois Department of Transportation’s aggregate improved subgrade (working platform) thickness design methodology. The current design recommendations do not consider aggregate properties, construction methods, or loading frequency. While the design typically works well, observations have indicated either excessively conservative designs, or the use of poorly performing aggregates. This results in an uneconomical use of resources. The performance of three dense graded aggregates having different physical characteristics, construction methods, and thickness was evaluated under controlled loading conditions in a test loop. The test loop results identified three primary factors affecting performance: 1) Aggregate angularity, fines content, and fines plasticity; 2) Aggregate layer compaction; and 3) Loading. Specifically, a crushed limestone having low plasticity fines and compacted to 95% of the maximum laboratory density was identified as a best practice and can be used at thicknesses less than the current design recommendations. However, uncrushed gravel and reclaimed asphalt pavement performed poorly. The test loop best practices were also evaluated on three construction projects. The results indicate pavement construction can be economized if aggregate properties are considered in improved subgrade thickness determination. The results also indicate aggregates with certain properties are not appropriate for improved subgrade applications.
  • Format:
    PDF
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:c021e2bf0f121bdbe78a66fafb6a2ebbd4db643938d568af86b55ac7704f211c10b0ed0e98b3f89cc37693166e0dcb2a7cd9c72348751ebf5faa452847b5eba5
  • Download URL:
  • File Type:
    Filetype[PDF - 3.73 MB ]
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