2005 Fall Midwest Concrete Consortium Meeting

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2005 Fall Midwest Concrete Consortium Meeting

• Bridge Deck Cracking Issues
• Ames, Iowa
• October 26, 2005

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Bridge Deck Cracking
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BRIDGE DECK CRACKINGDefining the Problem

• How big a problem is deck cracking across the
  country are any States finding it less of a
  problem than 10 years ago?
• Is any State quantifying the problem?
• What type of cracking is typically reported as a
  problem transverse, longitudinal, map. Other?
• Given new materials (ie improved epoxies,
  stainless steel cladding, etc.) is the deck
  cracking problem really a problem?

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IS THE DECK CRACKING MORE OF A DESIGN,
CONSTRUCTION OR MATERIALS PROBLEM?
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DESIGN, MATERIALS AND CONSTRUCTION RELATED CAUSES

• Simple or Continuous Spans
• Reinforcing Bar Size, Type, Alignment and Cover
• Restrained Plastic Shrinkage How important is
  rapid application of wet cure to reducing the
  amount of transverse cracking?
• What is the recommended maximum wind and minimum
  humidity conditions and maximum delay between the
  time of placement and application of wet cure.
  Does timing of cure application appreciably
  affect deck cracking?

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DESIGN, MATERIALS AND CONSTRUCTION RELATED CAUSES
(more)

• Restrained Thermal Shrinkage Heat of Hydration,
  Diurnal temperatures, depth and spacing of beams,
  depth of bridge deck
• Pour Sequence Induced Stresses What is the
  relationship between span length, girder spacing,
  and beam depth to choosing a pour sequence that
  will minimize sequence induced stressing?
• Traffic Induced Stresses Transverse cracking in
  negative moment areas and longitudinal cracking
  over beams

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MATERIALS SOLUTIONS

• Reduced Modulus of Elasticity lower concrete
  strengths
• Reduced heat of hydration
• Larger Aggregate Size, Well-Graded
• Water Cement Ratio
• Cement types What blends of other cementitious
  materials are States using to control deck
  cracking? Replacement levels Side effects
• Effects of additives

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CONSTRUCTION SOLUTIONS

• Pour Sequence Specifications
• Maximum Curing Temperature Specifications
• Pour Placement Specifications
• Environmental Requirements
• Nite Time Pours
• Rate of Pour
• Use of Additives

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MAINTENANCE SOLUTIONS

• Seal Cracks
• Do Nothing

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MINNESOTA Bridge Deck Cracking Possible
Solutions

• Maximum cementitious content to 611 pcy Current
  spec is minimum cementitious of 611 pcy
• 25-30 cement replacement with Coal Creek fly
  ash, slag, or a combination of both
• Well-graded aggregates (8-20 retained)
• Improved Curing Methods
• AMS Curing Compound
• 7-day wet cure
• Examining Pouring Sequences

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Bridge Deck Cracking Data Sheet
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Bridge Deck Cracking
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Bridge Deck Sealing

• Working on standard procedure
• Seeing both failures and successes
• Future?
• Determine if sealing is beneficial
• When to apply and then re-apply

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BRIDGE DECK CRACKING SEMINARPROPOSED
AGENDAFEDS WOULD PROVIDE TRAVEL FOR EXPERT
SPEAKERS