Transcript PPSX, 4.5MB

‘Characterisation of Granular Materials Rut
Resistance’
Austroads project TT1819
Pavement Technology Program
Andrew Papacostas (VicRoads) Austroads Project Manager
Austroads workshop – Wellington– 4th December 2014
Project objective
– The purpose of the project is to maximise the use of available materials
in road base construction, and reduce road agency costs, by developing
effective methods for evaluating the performance of unbound
granular materials.
– Propose improved laboratory testing for rut resistance characterisation
– Identify key material performance parameters to further develop material
specifications
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Project background
Project TT1163 ‘Better basis for bases’ (Optimum Use of Granular Bases)
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Project background
Report AP-R360-10 (Austroads 2010)
 Development of a wheel-tracker for laboratory characterisation
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Project background
Project TT1611 ‘Improved rut resistance characterisation’ (Austroads 2012)
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Project background
Development of the wheel tracking
testing procedures specimen
preparation and sealing
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TT1819 - Two Main Research Components
Laboratory Characterisation
Accelerated Pavement
– Wheel-tracking (WT)
– Repeated Load Triaxial Tests (RLT)
Austroads 2014 – Report AP-T267-14
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Accelerated Pavement Testing Component
• Test site: Dandenong South – VIC
• Indoor facility
• Experiments focused on granular base deformation
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Pavements structure
Sprayed seal
Unbound granular
base

Unbound granular
base
Cement treated
crushed rock
Re-used granular
materials
Stiff & not deforming
support
300 mm
150 mm
150 mm
Stabilised clay
including drainage
layer
Natural clay
subgrade
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Base Characteristics
Granite standard
Sample
No.
2514
PI
(wet prep.)
9-5
OMC*
(%)
6.6
MDD*
(t/m3)
2.22
Hornfels standard
2515
6–2
5.6
2.30
Granite increased plasticity
2516
12 - 6
5.5
2.29
Hornfels increased plasticity
2517
9-8
6.6
2.30
Material
* modified proctor compaction (AS 1289.5.2.1)
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Pavements layout
• 4 lanes x 3 (12 m long test sites)
Lane no.
1
2
3
4
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Material (20mm well-graded
crushed rock)
granite, low-plasticity
hornfels, low-plasticity
granite, increased plasticity
hornfels increased plasticity
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ALF trafficking program
• Forecast 1.5 years of pavement trafficking, this equates to
about 2½ million loading cycles
– 8,000 cycles per day
– 5 days per week
– 40 weeks operational per year
• 12 pavements
– 4 materials
– 3 replicates or different conditions
• Allows about 200,000 trafficking cycles per pavement
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ALF loading conditions
Objective: compare WT lab performance vs ALF performance
– WT tests (average contact stress ≈ 600 kPa)
– ALF: dual-tyre loads (11 R22.5)
 Applied loading conditions:
•
dual wheel (11R22.5 truck tyre) under 40kN
•
Load wandering ± 0.5 m according to a pseudo normal distribution
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Wheel-tracking test for UGM
• Data processing
5 profiles along the wheel-path
(-150, -75, 0, +75, +150 mm)
Number cycles 
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WT data: mean deformation & rut depth
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Mean profile deformation
Maximum rut depth
(Calculated across the tyre nominal width)
(Mathematical data processing)
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• Crushed hornfels (example)
Maximum rut depth
Test terminated before
40,000 cycles
Mean deformation
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Moisture sensitivity: TT1163 materials
Rhyolite
Hornfels
Limestone
Tuff
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WT .vs. ALF performance comparison
• ALF performance data (load = 60 kN on dual-wheel)
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WT .vs. ALF performance comparison
• ALF .vs. WT moisture conditions
Rhyolite
Hornfels
Limestone
Tuff
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Trafficking results
Lane 1
Lane 2
Lane 3
Lane 4
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Effect of moisture on pavement deformation
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MC4.7%
+ 0.5%
~ 70% OMC
MC
4.2%
~ 60% OMC
MC3.5%
– 0.7%
~ 50% OMC
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Laboratory Characterisation Component
Laboratory Characterisation
– Main focus: Wheel-tracking
– Repeated Load Triaxial Tests
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WT testing program
• Testing conditions
– 4 ALF materials
– For each material
• DD = ALF pavmt DD
• MC = three levels (ALF MC)
• Similar program is planned under triaxial conditions
– RLT (AGPT033)
– Shear strength testing
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Moisture sensitivity data
• Preliminary results
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RLT preparation conditions
• Data collected
– Australian & NZ context
– International practice
– Summary
– Definition of the preparation conditions
• Compaction (modified proctor hammer)
• Compaction moisture content
– MC < OMC vs OMC + dry-back
• Loading conditions
– AGPT033
– Drained (undrained)
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Overall objective (principle)
Laboratory Characterisation
Accelerated Pavement
Wheel-tracking (WT)
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