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

Steve Runge

Max Wallis

Tom Wilmot

Ian Hentschke

Acknowledgement

Lady Loretta mine

51.5km haul road

13 million tonnes of minerals

8 year life

135 km from Mount Isa

Annual wet and dry 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

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

• 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

Sprayed seal

In summary

• 51.5 km

• 510,000 t crushed base and subbase

• dry powder polymer in situ stabilisation

• $510,000 per km