Design and Construction of a Mining Haul RoadDr Richard Yeo, Austroads & Max Wallis, Polymix Industries

Steve Runge

Max Wallis

Tom Wilmot

Acknowledgement

Tom Wilmot

Lady Loretta mine

51.5km haul road

13 million tonnes of 13 million tonnes of

minerals

8 year life

135 km from

Mount Isa

Annual wet and

dry seasonsdry seasons

Environment has

a greater impact

than traffic

loading

Guide to Pavement Technology

Pavement design

focused on mitigating

the risk of saturation of

the pavement and

subgrade subgrade

Construction during dry

season

Design Traffic

Design vehicle – quad

road train

5 x 106 ESAs

• 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

Existing conditions

• existing compacted materials adopted

Variable subgrade:

• laterite soils

• very reactive black soils

• weathered rock outcrops

• 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

Fit for purpose pavement materials

• cost-effective new pavement

• use of non-standard gravels

• minimal maintenance

• ease of maintenance

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

In situ stabilisation

reduced capillary rise

• increased soaked CBR

• increased wet strength

• reduced permeability

• lower water required for compaction

60

80

100

120

140CBR (%)

0

20

40

60

A B C D EPavementmaterial:

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/m2Prime: AMC00: 0.8 l/m

Sprayed seal

In summary

• 51.5 km• 510,000 t crushed base and subbase• dry powder polymer in situ stabilisation

• $510,000 per km