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Stabilization of Soft Clay Subgrades in Virginia Phase I Laboratory Study

Stabilization of Soft Clay Subgrades in Virginia Phase I Laboratory Study. George Filz and Tom Brandon. Stabilization of Soft Clay Subgrades in Virginia Phase I Laboratory Study. Motivation for the research Issues to be considered Work tasks Schedule. Motivation.

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Stabilization of Soft Clay Subgrades in Virginia Phase I Laboratory Study

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  1. Stabilization of Soft Clay Subgrades in VirginiaPhase I Laboratory Study George Filz and Tom Brandon

  2. Stabilization of Soft Clay Subgrades in VirginiaPhase I Laboratory Study • Motivation for the research • Issues to be considered • Work tasks • Schedule

  3. Motivation The Problem and Potential Solutions • The Problem: Many road subgrades in Virginia consist of soft and wet clay that provide poor support for pavements • Potential Solutions: • Drying and compacting • Overexcavation and replacement • Designing a thick pavement section • Applying a chemical stabilizer

  4. Motivation Chemical Stabilizers • Lime: fine-grained quick, pelletized quick, hydrated • Cement • Synthetic polymers • Lignosulfonates • Salts • Petroleum emulsions • Enzymes • Acids

  5. Motivation Chemical Stabilizers • Lime: fine quick, pelletized quick, hydrated • Cement • Synthetic polymers • Lignosulfonates • Salts • Petroleum emulsions • Enzymes • Acids

  6. Motivation Chemical Stabilizers • Lime: fine quick, pelletized quick, hydrated • Cement • Synthetic polymers • Lignosulfonates • Salts • Petroleum emulsions • Enzymes • Acids

  7. Motivation A Related Virginia Tech Project • Rapid stabilization of soft clay subgrades for airfields for the US Air Force • The Air Force requires stabilization within 72 hours • Objectives of the Air Force and VDOT projects are different, but there is an opportunity of synergism

  8. Issues Mix Parameters • Soil type • Initial soil water content • Amendment type • Amendment dose rate • Compaction energy • Curing temperature • Curing time The test matrix could become very large!

  9. Issues Index and Performance Tests on Mixtures • Unconfined compression • CBR • Resilient modulus • Shrink/swell, durability, etc.

  10. Issues Index and Performance Tests on Mixtures • Unconfined compression • CBR • Resilient modulus • Shrink/swell, durability, etc.

  11. Work Tasks Work Task 1: Obtain Soil Samples • Lynchburg: Don French • Micaceous silt • Northern Virginia: David Shiells and Brian Edwards • Micaceous silt • Wet residual clay derived from igneous rocks • Marine clay • Blackjack clay • Richmond: Todd Beach • Micaceous silt • Marine clay • Staunton: David Morris • Wet residual clay derived from dolomite and limestone

  12. Work Tasks Work Task 1: Obtain Soil Samples • Lynchburg: Don French • Micaceous silt • Northern Virginia: David Shiells and Brian Edwards • Micaceous silt • Wet residual clay derived from igneous rocks • Marine clay • Blackjack clay • Richmond: Todd Beach • Micaceous silt • Marine clay • Staunton: David Morris • Wet residual clay derived from dolomite and limestone

  13. Work Tasks Work Task 2: Soil Characterization Tests • Natural water content • Organic content • Sulfate content • Particle size distribution • Atterberg limits • Moisture-density, standard Proctor energy • Mineralogy of the clay fraction

  14. Work Tasks Work Task 3: Select Amendments • Cement • Pelletized quick lime • Hydrated lime • A synthetic polymer • Lignosulfonate • Magnesium chloride

  15. Work Tasks Work Tasks 4 through 7 • Task 4: Develop test matrix in collaboration with VDOT and VTRC • Task 5: Prepare, cure, and test specimens • Task 6: Analyze results to identify trends and to design subsequent phases of research • Task 7: Prepare report

  16. Schedule Project Schedule

  17. Stabilization of Soft Clay Subgrades in VirginiaPhase I Laboratory Study So much money is spent on constructing, repairing, and rehabilitating pavements that even a modest effort to improve the subgrade can produce large cost savings.

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