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Design and Construction of a Mining Haul RoadDr Richard Yeo, Austroads & Max Wallis, Polymix Industries
135 km from Mount Isa
Annual wet and dry seasons
Environment has a greater impact than traffic loading
Pavement design focused on mitigating the risk of saturation of the pavement and subgrade
Construction during dry season
• unbound ‘track’
• running surface directly on the natural subgrade or worn well below this
• alignment varied by creek crossings and areas of black soils
• uneconomic to build up above natural ground
• existing compacted materials adopted
• very high operating costs
Variable subgrade:
• laterite soils
• very reactive black soils
• weathered rock outcrops
Existing conditions
• flooding anticipated during the design period
• possible inundation for up to 2 to 3 days
• road closed during flood events
Pavement inundation
• design involved use of rock won within the road reserve rather than importing material
• criteria included Particle Size Distribution, Plasticity Index (PI), Hardness, Linear Shrinkage
Fit for purpose pavement materials
In situ stabilisation adopted:
• correct mechanical deficiencies (particle size distribution and/or plasticity)
• increase strength or bearing capacity while maintaining a flexible pavement
• reduce permeability and/or moisture sensitivity
• cost-effective new pavement
• use of non-standard gravels
• minimal maintenance
• ease of maintenance
Fit for purpose pavement materials
Dry powder polymer selected on the basis of:
• proven track record – TIPES approved
• enabled a more open grading curve suited to the local materials
• reduced capillary rise
• increased soaked CBR
• increased wet strength
• reduced permeability
• lower water required for compaction
In situ stabilisation
0
20
40
60
80
100
120
140CBR (%)
A B C D EPavement
material:Unsoaked 4 day soaked 4 day soaked - stabilised
Sprayed seal
Binder Shoulders l/m2 Inbound l/m2 Outbound l/m2 Aggregate
S4.5S 1.7 1.4 1.0 10 mm
S4.5S 1.9 1.7 1.4 20 mm
Prime: AMC00: 0.8 l/m2