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Optimizing the Risk and Cost of Subgrade QA/QC Program

Optimizing the Risk and Cost of Subgrade QA/QC Program. ADCP. FWD. LWD. Presented by : Kamran Majidzadeh, PhD, PE President, Resource International, Inc. The Need for Risk and Cost Analysis. A gradual shift in acceptance criteria from specifications-based to performance-based programs

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Optimizing the Risk and Cost of Subgrade QA/QC Program

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  1. Optimizing the Risk and Cost of Subgrade QA/QC Program ADCP FWD LWD Presented by: Kamran Majidzadeh, PhD, PE President, Resource International, Inc.

  2. The Need for Risk and Cost Analysis • A gradual shift in acceptance criteria from specifications-based to performance-based programs • New trends in project delivery methods • Design-Build projects • Private-Public Partnerships • Development of new construction/material technologies and innovative tools • Use of contractor’s QC data in project acceptance • A national move toward MEPDG

  3. Risk and Cost Analysis for Embankments and Natural Subgrade • Conventional geotechnical approach: • Soil sampling • Automated Dynamic Cone Penetrometer (ADCP) • Nuclear Density Gauge (NDG) NDG & LWD NDG

  4. Risk and Cost Analysis for Embankments and Natural Subgrade • Innovative tools: • Lightweight Deflectometer (LWD) • Falling Weight Deflectometer (FWD) • Automated Dynamic Cone Penetrometer (ADCP) ADCP LWD FWD

  5. Costs and Frequency of QA/QC Programs

  6. Project Examples Harrison County Oil & Gas Haul Roads Project: • Natural subgrade Ohio Turnpike Pavement Base Replacement Projects: • MP 95.8-101.2 • Natural subgrade • Stabilized subgrade • Effective subgrade • MP 144-149.3 • Natural subgrade

  7. A Statistical Model for Sampling Where: CV: Coefficient of Variation (ratio of the standard deviation to the average) e: Acceptable error. The ratio of e to is recommended to be within +/- 10% N: Maximum number of sampling units for a given section n: Minimum number of sampling units within that specific section to obtain a statistically adequate estimate at the prescribed level of error

  8. Natural Subgrade Harrison County Oil & Gas Haul Roads

  9. Natural Subgrade Harrison County Oil & Gas Haul Roads Recommendation: Increase sampling size

  10. Natural Subgrade Harrison County Oil & Gas Haul Roads

  11. Natural Subgrade Ohio Turnpike Pavement Base Replacement Program (MP 95.8-101.2)

  12. Natural Subgrade Ohio Turnpike Pavement Base Replacement Program (MP 95.8-101.2) Recommendation: ODOT Specifications

  13. Effective Stabilized Layer (ADCP) Ohio Turnpike Pavement Base Replacement Program (MP 95.8-101.2) Effective Stabilized Layer CBR 25 CBR from lab UCCS data 20 26.5 26 19.5 15 10 5 0 50 10 20 30 40 0

  14. Effective Stabilized Subgrade Ohio Turnpike Pavement Base Replacement Program (MP 95.8-101.2) Recommendation: 44% Less Sampling

  15. Effective Subgrade CBR Ohio Turnpike Pavement Base Replacement Program (MP 95.8-101.2) 25 GB1 Design CBR = 4 20 15 Frequency (%) 10 5 0 0 5 10 15 20 25 CBR

  16. Effective Subgrade Ohio Turnpike Pavement Base Replacement Program (MP 95.8-101.2) Recommendation: 40% Less Sampling

  17. Natural Subgrade Ohio Turnpike Pavement Base Replacement Program (MP 144-149.3) Design CBR = 6

  18. Natural Subgrade Ohio Turnpike Pavement Base Replacement Program (MP 144-149.3) Recommendation: Reduce Sampling 56%

  19. Summary of Results of Analysis Harrison County Oil & Gas Haul Roads Project: • Natural subgrade • Increase sampling or use FWD Ohio Turnpike Pavement Base Replacement Projects: • MP 95.8-101.2 • Natural subgrade • Follow ODOT Specification • Stabilized subgrade • 44% less sampling size • Effective subgrade • 40% less sampling • MP 144-149.3 • Natural subgrade • 56% reduction (910’ spacing)

  20. Conclusions • Cost and Risk Analysis • The statistical method presented provides a tool to study how to reduce the cost and increase the reliability of QA/QC sampling • Nondestructive testing can generally be completed in a single day for project lengths up to 20 miles and requires minimal traffic control and minimal risk • Cost of field exploration for nondestructive FWD and LWD testing is approximately half the cost of conventional testing for project lengths greater than 8 to 10 miles at a minimal risk • Conventional testing generally takes about one day for every three miles of project length, considering a testing interval of ¼-mile and typically requires lane closures

  21. Acknowledgement The authors wish to thank the co-authors of the paper titled Application of Innovative Tools in Optimizing Risk and Cost of Subgrade QA/QC for use of the material presented in the subject publication. More specifically, thanks to the Ohio Turnpike and Infrastructure Commission for the use of previously published field data and E.L. Robinson Engineering for allowing us to share with you our thoughts on the subject matter.

  22. Thank You! Kamran Majidzadeh, PhD, PE President Resource International, Inc. Phone: 614.823.4949 Email: KamranM@resourceinternational.com www.resourceinternational.com Laith Tashman, PhD, PE, PMP Associate Professor Department of Civil Engineering Wentworth Institute of Technology (Boston, MA) Phone: 617.989.4172 Email: TashmanL@wit.edu

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