Details:

• Creators:
  White, David ; Li, Shengting ; Vennapusa, Pavana

  White, David ; Li, Shengting ; Vennapusa, Pavana Less -
• Corporate Creators:
  Iowa State University. Center for Earthworks Engineering Research
• Corporate Contributors:
  Iowa. Highway Research Board
• Subject/TRT Terms:
  [+]

  Compaction Embankment Quality Embankments Moisture-density Testing Moisture Content Saturated Soils Soil Compaction Soil Tests Unsaturated Soils
• Publication/ Report Number:
  InTrans Project 14-507
• Resource Type:
  Tech Report
• Geographical Coverage:
  Iowa
• Corporate Publisher:
  Iowa. Highway Research Board
• Abstract:
  A specification for contractor moisture quality control (QC) in roadway embankment construction has been in use for approximately 10
  
  years in Iowa on about 190 projects. The use of this QC specification and the development of the soils certification program for the Iowa
  
  Department of Transportation (DOT) originated from Iowa Highway Research Board (IHRB) embankment quality research projects.
  
  Since this research, the Iowa DOT has applied compaction with moisture control on most embankment work under pavements.
  
  This study set out to independently evaluate the actual quality of compaction using the current specifications. Results show that Proctor
  
  tests conducted by Iowa State University (ISU) using representative material obtained from each test section where field testing was
  
  conducted had optimum moisture contents and maximum dry densities that are different from what was selected by the Iowa DOT for
  
  QC/quality assurance (QA) testing. Comparisons between the measured and selected values showed a standard error of 2.9 lb/ft3 for
  
  maximum dry density and 2.1% for optimum moisture content. The difference in optimum moisture content was as high as 4% and the
  
  difference in maximum dry density was as high as 6.5 lb/ft3. The difference at most test locations, however, were within the allowable
  
  variation suggested in AASHTO T 99 for test results between different laboratories. The ISU testing results showed higher rates of data
  
  outside of the target limits specified based on the available contractor QC data for cohesive materials. Also, during construction
  
  observations, wet fill materials were often observed. Several test points indicated that materials were placed and accepted at wet of the
  
  target moisture contents. The statistical analysis results indicate that the results obtained from this study showed improvements over
  
  results from previous embankment quality research projects (TR-401 Phases I through III and TR-492) in terms of the percentage of
  
  data that fell within the specification limits. Although there was evidence of improvement, QC/QA results are not consistently meeting
  
  the target limits/values.
  
  Recommendations are provided in this report for Iowa DOT consideration with three proposed options for improvements to the current
  
  specifications. Option 1 provides enhancements to current specifications in terms of material-dependent control limits, training,
  
  sampling, and process control. Option 2 addresses development of alternative specifications that incorporate dynamic cone penetrometer
  
  or light weight deflectometer testing into QC/QA. Option 3 addresses incorporating calibrated intelligent compaction measurements into
  
  QC/QA.
  
  
• Format:
  PDF
• Funding:
  IHRB Project TR-677
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  [+]

  urn:sha256:05d4abce4a9e637a5b8670f16fcc1bb86646c5d5de5a6c4d6495d4387526e4fc
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/30692/dot_30692_DS1.pdf
• File Type:
  [PDF-10.04 MB]