Durability of Post-Tensioned Structures Grout Specifications Durability Design Details

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Durability of Post-Tensioned StructuresGrout
SpecificationsDurability Design Details
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Durability and Post-Tensioning

• Extremely durable when properly constructed
• Crack control
• Multiple protection levels

moisture, Cl-, CO2
concrete
duct
grout
The grout is the last level of protection for the
strand
strand
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Purpose of Grout

• Corrosion protection
• Bond

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Properties

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

Bleed
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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
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Bleed Lenses

• Voids
• Loss of protective environment

9 ¾ bleed column
Intermediate lense
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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
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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