Updated mechanistic design method for rigid pavements cncPave

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Updated mechanistic design method for rigid
pavementscncPave
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Scope

• Background
• Research
• Outcomes
• Major changes
• Demonstration
• Future research

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Background
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Background

• cncRisk
• Predicted risk of failure
• cncPave
• Predicted extent of failure i.t.o. cracking,
  pumping, faulting and crack spacing for CRCP
• Inputs included shrinkage and crack/joint width

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Recent research
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Recent Research

• HVS tests on trial sections at Hilton
• HVS tests on inlay at Town Hill
• FWD tests on N2
• Postgrad research shrinkage and strength
• Thin concrete pavements at Roodekrans
• Ongoing monitoring of existing roads
• N4 Witbank Middleburg
• N1 Ben Schoeman

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Recent Research

• HVS tests on trial sections at Hilton
• Four sections, dowelled and undowelled with two
  aggregate types
• Aggregate interlock and dowel load transfer
• Effect of crack width, temperature, shrinkage etc
• HVS tests on inlay at Town Hill
• Determine remaining life
• Development of punchouts
• FWD tests on N2
• Effect of temperature on crack movement and load
  transfer
• Effect of traffic on load transfer
• Postgrad research
• Relationship between compressive, flexural and
  indirect tensile strengths

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Outcomes
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Outcomes

• Reports on Gautrans website shortly
• Construction
• Level 1 analysis - Hilton
• Level 1 analysis - Inlay at Town Hill
• Level 2 analysis - Hilton and Town Hill
• MSc Shrinkage at Wits
• MSc Strength at UP

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Major changes to cncPave
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Changes

• Replaced shrinkage value with modified RILEM
  prediction model
• Uses RH, cement type, content, water content,
  temperature etc to predict shrinkage
• Shrinkage used to predict crack width
• Long term change in load transfer for dowels and
  aggregate interlock

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Changes cont.

• Inputs
• Changed variables
• Increased constants
• Included cost of support
• Outputs
• Deterioration with time
• What-if feature more user friendly

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Demonstration
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• www.cncipave.org.za
• www.cnci.org.za

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Further research
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• Effect of environment Proposal from Wits
• Subbase erosion UP
• Bond between concrete and support layer