When talking about haul road optimization there are many parameters that can describe it. These are economic efficiency, environmental effects, safety, etc. Since haul road has to bear heavy dynamic loads due to heavy machinery on construction sites, mines, quarries, etc., they have to be very strong.
Haul road construction is usually performed with little expertise, resulting in expensive maintenance and high vehicle operating costs. Truck haulage costs can be as high as 50 % of total surface mining costs and up to 60 % of total forestry operation costs. The savings from haul road optimization can thus be significant.
Conventional haul road building incorporates a lot of removing of in situ material and bringing in more appropriate ex situ materials. Haul road consists of three different layers: sub-base, base and driving surface.
- For the deepest layer, sub-base, placement of at least 500mm thick layer is needed, filled with coarse material not bigger than 100mm. This follows rough shaping in alignment with the profile of final driving surface. Compaction is done by heavy rubber-tyred machinery.
- Middle layer or road base is made of at least 300mm thick layer, filled with particles not bigger than 50mm. Here is needed finer road alignment than for sub-base and drainage systems should be installed in this layer. Compaction is also done by heavy rubber-tyred machinery, but road material has to be slightly wet.
- Construction of the topmost layer, driving surface, is the most complex of the three. Haul road optimization is achieved if surface enables good traction and doesn’t release excessive dust. Conventional approach is placement of 100mm thick layer filled with particles not bigger than 30mm. Additionally, this material has to be weather resistant and not jagged or sharp-edged to prevent tyre damage. Materials with high fines content or unconsolidated materials are not allowed. Compaction as for road base is needed.
Due to needed excavations and large amounts of ex situ materials, traditional haul road building is very energy, material, machinery and labour demanding. This also means huge costs and negative impact on environment.
Global Road Technology (GRT) changed concept of haul road optimization by promoting use of in situ materials. GRT developed products for soil stabilization and dust suppression that are compatible with any type of soil and even crushed old asphalt.
GRT7000 can be used to stabilize and seal haul roads. It works by physically and chemically bonding soil or old pavement particles together, leading to haul road optimization through improved compressive strengths, high tensile resilience, and water impermeability. Soil stabilizer GRT7000 achieves extremely high UCS results with relatively low dosage rates. For example, testing with as little as 0.7% by mass has seen results over +6MPa achieved.
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If used as dust suppressant, maintenance is required every 12 to 16 weeks depending on usage loading. Due to the cumulative, residual nature of the product, the rate of application of GRT7000 reduces over time, and thus maintenance becomes more economical each year. Costs savings of 30-40% are achieved due to removal of daily watering and grading, less wear and tear on vehicles, improved haul times, and elimination of downtime during and after wet weather (independently verified by Deloitte).
Safety and working efficiency are supported by improved skid resistance and decreased rolling resistance. GRT7000 is certified environment-friendly and all activities associated with it have low carbon footprint. Global Road Technology succeeded to accomplish haul road optimization in all aspects: cost efficiency, environmental effects, working efficiency and safety.
For more information regarding Global Road Technology or haul road optimization please contact GRT.
