Concrete Test Section at Roodekrans

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Concrete Test Sectionat Roodekrans

• RPF
• November 2002

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Outline

• Objectives
• Design details Material properties
• Instrumentation
• Traffic
• Construction
• Present condition
• Preliminary findings
• Future

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Objectives

• Calibrate design method cncPave
• Quantify and define failure of low-volume
  concrete pavements
• Compare the performance of pavements and subbase
  types
• Evaluate effect of joint spacing load transfer
  mechanisms

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Parties

• Cement and Concrete Institute
• CSIR Transportek
• University of Pretoria
• Alpha Stone and Readymix
• BKS
• Raubex

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Design details

• Section 1
• 75 mm SFRC (30 kg/m3) Joint spacing 3 m
• 140 mm Foam concrete subbase
• In situ
• Section 2
• 75 mm SFRC (30 kg/m3) Joint spacing 6 4 m
• 125 mm CTS
• In situ

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Design details

• Section 3
• 75 mm SFRC (30 kg/m3) No joints
• 25 mm ETB
• 125 mm CTS
• In situ

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Design details

• Section 4
• 50 mm CRCP with mesh
• 50 mm ETB
• 125 mm CTS
• In situ
• Section 5
• 75 mm CRCP with mesh
• 25 mm ETB
• 125 mm CTS
• In situ

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Design details

• Section 6
• 100 mm CRCP with mesh
• 125 mm CTS
• In situ

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Design details

• Section 7
• 100 mm butt joints spaced 2 and 3 m
• 125 mm CTS
• In situ
• Section 8
• 100 mm butt joints spaced 2 and 3 m
• 40 mm continuously graded asphalt
• 100 mm CTS
• In situ

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Design details

• Section 9
• 140 mm butt joints spaced 2, 3 and 4 m
• 125 mm gravel
• In situ
• Section 10
• 140 mm shrinkage joints spaced 2, 3 and 4 m
• 125 gravel
• In situ

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Design details

• Section 11
• 140 mm dowel joints spaced 2, 3 4 m
  25 mm dowels _at_ 300 c/c
• 125 mm gravel
• In situ

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Material Properties

• In situ
• CBR 80
• Quartzitic gravel A-1-a G5/G6
• Compaction 97 Mod. AASHTO
• FWD deflections ? 1,0 mm

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Material Properties

• Subbase
• Gravel same as in situ material
• Compaction 97 Mod. AASHTO
• Stabilized with 2 CEM I 42.5 (C3)
• UCS ? 2000 kPa
• FWD deflection 0,9 mm and Stab 0,5 mm

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Material Properties

• ETB
• Subbase material
• Stabilized with 1,5 anionic stable grade
  emulsion 1 cement
• Asphalt
• Continuously graded hot mix 60/70 pen
• 12 mm aggregate size

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Material Properties

• Concrete
• Strength
• fc 22 - 42 MPa
• ff 3,7 - 5,6 MPa
• Mod E 24 - 33 GPa
• Shrinkage 0,05 - 0,06
• Cement CEM I 42,5/GGBS 80/20

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Instrumentation

• LVDTs
• Centre
• Side
• Thermocouples
• Conventional
• Programmable
• Weather station
• Falling Weight Deflectometer (FWD)

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Construction

• Readymix concrete
• Compaction by poker and beam
• Curing compound
• Plastic sheeting

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Traffic

• Trucks leaving quarry
• Weigh bridge data
• No of axles
• Approximately 300 E80s per day
• To date 80 000 E 80s

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Observations

• Very little distress to date
• Vertical movement at joints under traffic
• Rocking of slabs on foam concrete
• Some corner and mid-slab cracking
• Plastic shrinkage cracks not affecting
  performance
• Some cracks becoming active

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Preliminary Findings

• Performance 100 better than expected, thin
  CRCP sections doing very well
• Critical thickness around 90 mm
• Higher deflections at cracks joints forerunner
  of relative vertical movement
• Slab curling dry erosion lead to pumping
• Failure in the eyes of the beholder

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Future

• Ongoing observations measurements of
  deflections and movements (FWD)
• Continual recording of traffic loading
• Panel to define failure for different types of
  pavements and facilities
• Analysis of results and calibration of design
  program cncPave
• Availability of data

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Thank you
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