Mass Stabilising
Mass stabilisation is a relatively new ground improvement method for improving the strength of very low strength, high moisture soils.
Stabilisation is achieved by mixing an appropriate amount of dry binder throughout the volume of the treated soil layer, to provide 100% treatement coverage insitu to a depth of up to 5 meters. The binder can consist of a single substance, a mixture of various mixes of cement, lime, fly ash or furnace slag. Binder mixtures are selected depending on soil characteristics and strength requirements. Mass stabilisation may also be combined with another stabilisation methods such as deep soil mixing.
The main purposes of Mass Stabilisation are:
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To increase the strength of the soft soil
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To improve the deformation properties of the soft soil (reduce settlements)
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To increase dynamic stiffness of the soft soil
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To remediate contaminated soil by immoblising contaminants
The benefits of Mass Stabilisation are:
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It is a rapid ground improvement method, and can be adapted to varying soil conditions
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It is in most cases economically efficient and saves materials and energy and generally is the most cost effective form of insitu 'shallow' stabilising
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It can eliminate the requirement for costly dewatering, below ground retaining walls, digout and replacement methods
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It improves the engineering properties of the soil and can be flexibly linked with other structures and with the surroundings (no harmful settlement differences)
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Transfer of the natural soil elsewhere is not needed, so there is less transportation and traffic pollution and no need for disposal sites and offsite transport
Mass Stabilising is achieved by
pumping hydraulic binder at pressure through a delivery line. The
binder is then ejected through a specifically designed manifold
outlet at the rotor head.
A high pressure tank is used for binder pumping and
delivery.
Load cells on the tank accurately control, measure and record
binder delivery and to ensure target application rates are
achieved. Typically, pumping of binder can be difficult to achieve,
but with the correct pressures, air flow, load cells and outlet
manifold, high level QA and mixing can be achie
ved.
Mass Stabilisation in New Zealand
Hiway introduced Mass Stabilisation into New Zealand in 2005.This
technology was developed to insitu stabilise a range of very
high moisture content soils including alluvium, peats and
contaminated soils.
Over the past five years Hiway Stabilizers have completed many projects of varying sizes and in various conditions. Some examples of these projects are:
- Orakei Port Mass Stabilisation to strengthen marine mud for a pipeline excavation
- Fergusson Reclamation Mass Stabilisation of low strength dredged materials for a new container terminal
- Watercare Mangere Mass Stabilisation of Bio Solids
- Whakatane Storm Water Upgrade, below ground retention tank
- Silt ponds, various sizes from subdivisions through to large scale earthworks projects
- Tui Mine site remediation of contaminated mine tailings.
Tui Mine Alkalinity Trials
Tui Mine Alkalinity Trials
