Soil stabilisation is a procedure wherein the engineering properties of the soil are altered and enhanced to increase its suitability for construction purposes. In civil engineering, soil stabilization is a technique to refine and improve the engineering properties of soils such as mechanical strength, permeability, compressibility, durability and plasticity. Physical or mechanical improvement is common but some schools of thought prefer to use the term ‘stabilization’ in reference to chemical improvements in the soil properties by adding chemical admixtures.  

For any construction project, whether it’s a building, a road or an airfield, the base soil acts as the foundation. Additionally, the soil is one of the crucial construction raw materials. As such, soil should possess properties that create a strong foundation.

The practice of stabilizing or modifying soils dates back to the age of the Romans. Other nations such as the United States and China among many others adopted it in the latter half of the 20thcentury. There were several reasons for it. Not all sites offer favourable construction conditions. At such sites, a contractor usually has four main options at his disposal. They are:

  • Substituting poor grade soils with aggregates possessing more favourable engineering properties.
  • Looking for a new construction site.
  • Modifying the proposed structure to suit the poor engineering properties of the current soil.
  • Finally, enhancing the properties of soil on site.

Options 1, 2 and 3 are not only expensive but also impractical. Today, with better research and more effective equipment and materials, soil stabilization, option 4 on the list, is considered the most feasible option for all construction purposes. Some definitions of it also refer to the process as soil modification.

What are the benefits of Soil Stabilization?

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  • Strength improvement including shearing strength and compressive strength 
  • Mitigating and reducing volume instability and swelling potential and controlling shrinkage 
  • Reducing plasticity index (PI)
  • Reducing permeability 
  • Reducing soil compressibility, deformation and settlement 
  • Reducing clay/silt sized particles 
  • Improving resilient modulus 
  • Improving durability to resist unfavourable environmental conditions such as freeze-thaw or wet-dry cycles, erosion and weathering
  • Dust control
  • Waterproofing

Soil Stabilisation Methods:

19GRT-Global-Road-Technology-Soil-Stabilization

When speaking about the definitions of it, it is important to consider the methods used for the same. Soils are stabilized either by subjecting it to mechanical processes or by adding a chemical or additive. Compaction dates back to the Roman times and even earlier but particularly the 18th century where the interurban travel and its importance was recognized. It was driven by the need for ground improvement . Compaction is one of the commonly used mechanical processes. It increases the density of the soil by eliminating air from between grains. To date, soil compaction constitutes one of the most commonly used construction practices in civil engineering. Soil that has been compacted has better load-bearing capacities and reduces porosity. Densification through soil compaction improves soil properties, it increases soil strength, reduces compressibility and permeability. Although compaction often appears to be a simple practical process, it is very complex on analysis under external and environmental loads. Compacted soil can exhibit various behaviours ranging from plastic deformation, in particular, swelling and collapse compression under wetting  and cracking under drying this is also in relation to changes in density due to wet or dry cycles. 

Majority of the problems related to soil use are attributed to unfavourable interactions between water and soil. Engineering properties are negatively impacted on increase of water content with examples such as decrease in cohesion, swelling of soil, alternating dry out shrinkage and wetting effects which destroy soil structure as do frost-thaw variations. Chemical soil stabilizers confer favourable characteristics regardless of the moisture in the environment through modification of interactions between water and soil by surface reactions in the process altering the behaviour of the soil with respect to water effects.  As far as the use of chemicals is concerned, lime, bituminous and cement are some of the additives added to the soil. These additives and binders when they come in contact with the pozzolanic minerals present in the soil or water, they react to form composite materials. Soil-cement is better known as a mechanical additive because like mechanical processes it does not alter the chemical properties of soil like lime would do, but simply enhances its existing properties. The surface activity of the soil particles, the polarity of the surfaces and their water absorption, and the entire adsorption complex play the most critical roles although aggregation extent of the particles and changes in degree of aggregation achieved by modification of the equilibrium of intergranular repulsive and attractive forces. In essence, chemical stabilization is performed to favourably change the soil-water interactions. 

The method of stabilizing soils is a commonly undertaken procedure in the construction of airfields, parking lots, landfills, embankments, roads and foundations, waterway management, agriculture and mining sites. The type of stabilization that might be used depends on the site; it may use single method or a combination of the two.

GRT Soil Stabilization:

Global Road Technology is a world leader in stabilization and dust control solutions.  The innovative range of products has revolutionized the definition of it in-situ by creating for environment-friendly construction projects. It holds the future of road stabilization and surfacing with its GRT9000 and GRT PCM which when integrated into pavement and subgrade materials delivers strong, semi-flexible and water-impermeable layers.  Additionally, the GRT7000 and GRT5000 polymer sealing and all purpose control products are the preferred choices for dust suppression. They work like a dust palliative and a sealant simultaneously to trap fine soil particles preventing them from becoming airborne.

The Global Road Technology lineup also includes bonding and capping agents to create strong foundations, capping layers and road sub-base layers. If this is not enough reason, GRT products offer the longevity and stability that no other soil stabilization and dust suppression systems on the market can offer, all products have been tested extensively by the world’s leading environmental risk management company.

The Definition of soil stabilization can be explained by any number of our industry-leading consultants.

For more information on Global Road Technology’s Soil Stabilization Methods, Contact GRT.

 

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REFERENCES 

Behnood, A. 2018. Soil and clay stabilization with calcium and non-calcium-based additives: A state of the art review with challenges, approaches and techniques. Transportation Geotechnics. 17. 14-32. 

Gaspar. 1979. Chemical soil stabilization methods. Book chapter 7. Hungarian Road Research Institute. 

Kodikara, J., Islam, T., and Sounthararajah, A. 2018. Review of soil compaction: History and recent developments. Transportation Geotechnics. 17. 24-34.