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Soil stabilization
Soil stabilization a general term for any physical, chemical, biological, or combined method of changing a natural soil to meet an engineering purpose. Improvements include increasing the weight bearing capabilities and performance of in-situ subsoils, sands, and other waste materials in order to strengthen road surfaces.
The prime objective of soil stabilization is to improve the California Bearing Ratio of in-situ soils by 4 to 6 times. The other prime objective of soil stabilization is to improve on-site materials to create a solid and strong sub-base and base courses. In certain regions of the world, typically developing countries and now more frequently in developed countries, soil stabilization is being used to construct the entire road.
In the past, soil stabilization was done by utilizing the binding properties of clay soils, cement-based products such as soil cement, and/or utilizing the "rammed earth" technique (compaction) and lime.
Some of the renewable technologies are: enzymes, surfactants, biopolymers, synthetic polymers, co-polymer based products, cross-linking styrene acrylic polymers, tree resins, ionic stabilizers, fiber reinforcement, calcium chloride, calcite, sodium chloride, magnesium chloride and more. Some of these new stabilizing techniques create hydrophobic surfaces and mass that prevent road failure from water penetration or heavy frosts by inhibiting the ingress of water into the treated layer.[2]
However, recent technology has increased the number of traditional additives used for soil stabilization purposes. Such non-traditional stabilizers include: Polymer based products (e.g. cross-linking water-based styrene acrylic polymers that significantly improves the load-bearing capacity and tensile strength of treated soils), Copolymer Based Products, fiber reinforcement, calcium chloride, and Sodium Chloride.
Traditionally and widely accepted types of soil stabilization techniques use products such as bitumen emulsions which can be used as a binding agents for producing a road base. However, bitumen is not environmentally friendly and becomes brittle when it dries out. Portland cement has been used as an alternative to soil stabilization. However, this can often be expensive and is not a very good "green" alternative. Cement fly ash, lime fly ash (separately, or with cement or lime), bitumen, tar, cement kiln dust (CKD), tree resin and ionic stabilizers are all commonly used stabilizing agents.
benefits of soil stabilisation
Stabilising soils with binders is now an extremely cost effective method of converting poor quality soil into a strong impermeable medium. This enables production of pavements, embankments, reinforced earth structures, railways, bulk fill applications, housing and industrial units in areas where they were not previously economically viable. Many years experience has proved the effectiveness of this method. This, combined with rising costs of conventional civil engineering, has transformed soil stabilisation into the most cost effective method of preparing sites for all construction projects.
Saves Money
You can usually save significant sums of money by soil stabilisation compared to the traditional "dig and dump" method. Dig and dump incurs the cost of vehicle movement, landfill tax and buying aggregates.
Savings by Design
Soils treated binders can be designed to be stronger than conventional granular sub base. Using this type of material in a pavement or foundation means that the strength is considerably enhanced. This strength can be used to reduce the thickness of the foundation or the thickness of the subsequent layers. Concrete or blacktop can be laid directly onto stabilised soil. Savings in granular sub base, concrete and bituminous materials are all possible.
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Saves Time
Soil stabilisation can often shortens the time taken to complete a project by minimising the site preparation time and reducing tipping or import . The process also enables wet ground to be dried and strengthened for immediate use.
Winter Working
Soil stabilisation, using lime is without doubt the most effective way of drying a wet site. The addition of quicklime instantly dries up wet soils and allows extended working in wet conditions and into the winter. Ideal for haul roads and those difficult sites.
Saves Environmental Impact
Imagine removing 50 lorry loads of soil and bringing in 50 loads of imported material. One 30 tonne load of binder can eliminate these 100 vehicle movements. Less cost, less congestion and no furious neighbours. An environmental solution with many benefits.
Saves Waste
There is no need to import new material when the soil on site can be used after a simple treatment process. Even Type 1 sub base is not required as the same strength and properties can be achieved using the soils on site. Costly and time-consuming importation of new material and generation of large quantities of waste is therefore eliminated.
Saves Landfill Taxes
Soil stabilisation uses the soils available on your site. These are improved to give the properties required for construction. This can vary from a simple process to enable use in landscaping or embankments right through to use in sub base. All the available soils can be used, so tipping is virtually eliminated. No need for any more tipping charges, just stabilise the soils on site and use them.