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I-99 HPC Initiative: Upcoming Work

I-99 HPC Initiative: Upcoming Work. Phase II Testing. 25 Phase II Mixes Control, silica fume, fly ash, slag, ternary, Aquron, Ipanex Phase II Testing Freeze-thaw, scaling, ASR, Cloride ion permeability, shrinkage, abrasion Continued corrosion testing. Revised Scope.

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I-99 HPC Initiative: Upcoming Work

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  1. I-99 HPC Initiative:Upcoming Work

  2. Phase II Testing • 25 Phase II Mixes • Control, silica fume, fly ash, slag, ternary, Aquron, Ipanex • Phase II Testing • Freeze-thaw, scaling, ASR, Cloride ion permeability, shrinkage, abrasion • Continued corrosion testing

  3. Revised Scope • Delay in bridge construction for I-99 section C-10 (15 single spans) • Focus on lab testing and best practices guide • Development of instrumentation plan • New HPC projects • Districts 9-0 and 4-0 HPC decks for summer 2002 • New grouting specifications and details for Post-Tensioning

  4. HPC Decks – Summer 2002 • Kernville viaduct, Johnstown, District 9-0 • 3300 ft • multi-span, curved composite bridge • District 4-0 • Approximately 500 ft

  5. Tasks for Summer HPC Decks • Review mix designs • Review casting sequence • Review quality control data during casting • Log of construction practices • Evaluate placing and curing techniques to improve concrete quality • Instrumentation • Companion slabs

  6. Instrumentation embedment • Temperature • Strain • Deflections • Corrosion monitoring surface sister bar

  7. Durability of Post-Tensioned StructuresGrout SpecificationsDurability Design Details

  8. Durability and Post-Tensioning moisture, Cl-, CO2 • Extremely durable when properly constructed • Crack control • Multiple protection levels concrete duct grout The grout is the last level of protection for the strand strand

  9. Purpose of Grout • Corrosion protection • Bond

  10. Properties • Fluidity • Bleed • Segregation • Set Time • Strength • Permeability • Volume Change • Corrosion Protection Bleed

  11. Bleed in Grouts Bleed • Bleed water is trapped in duct • Higher vertical rises = higher pressures and more bleed water • Strand promotes bleed by wicking Intermediate lense

  12. Bleed Lenses • Voids • Loss of protective environment 9 ¾” bleed column Intermediate lense

  13. Keys to a Good Grout • Completely fills duct • Low permeability • Appropriate bleed resistance • Careful use of admixtures Many admixtures help one grout property while degrading another

  14. Tasks under WO-81 • Literature review and summary of current practice • Development of specification language, details, and revisions to PennDOT publications • Scope includes • Grouting (materials, procedures, venting) • Durability details (anchorage, duct material) • Inspection/repair • Training of personnel

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