Embankment quality and assessment of moisture control implementation.

Details

• Creators:
  White, David ; Li, Shengting ; Vennapusa, Pavana
• Corporate Creators:
  Iowa State University. Center for Earthworks Engineering Research
• Corporate Contributors:
  Iowa. Highway Research Board
• Subject/TRT Terms:
  • Moisture content
  • Embankments
  • Soil tests
  • Soil compaction
  • Saturated soils
  • Unsaturated soils
  • compaction
  • embankment quality
  • moisture-density testing
• 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.
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• Format:
  PDF
• Funding:
  IHRB Project TR-677
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/30692/dot_30692_DS1.pdf
• File Type:
  [PDF - 10.04 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:05d4abce4a9e637a5b8670f16fcc1bb86646c5d5de5a6c4d6495d4387526e4fc