Soil Stabilization is the biological, chemical or mechanical modification of soil engineering properties. In civil engineering, soil stabilization is a technique to refine and improve the engineering properties of soils. These properties include 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, soil is one of the crucial construction raw materials. As such, the 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.
What is the soil stabilization process?
- Understand the material properties involved in the mixture and the intended outcome after mixing.
- Evaluate the effects of the process on the nearby structures and surrounding conditions.
- Consider factors such as mixing and spreading, selection of roller, compaction, layer thickness.
- Choose the sequence of operation
- If working with chemicals evaluate curing, environmental and climatic conditions.
What are the materials used in soil stabilization?
The materials used in soil stabilization depend on what technique is being employed. The following list includes everything from biological, chemical and mechanical soil stabilization techniques:
- Different grades of soil.
- Different grades of aggregates.
- Seedlings
- Seeds
- Hydromulch mixtures
- Hydroseeding mixtures
- Geomaterials – geogrids, geoblankets
- Polymers -synthetic and natural
- Synthetic resins
- Emulsions
- Cement
- Lime
- Fly ash
- Bitumen
- Recycled and waste products – solid municipal, mining and industrial wastes.
What are the soil stabilisation methods?
- Mechanical stabilization – its objective is to achieve dense, well graded material by mixing and compacting two or more soils and/or aggregates.
- Chemical stabilization – refers to the alteration of soil properties by changing its chemical make-up with different additives like lime, cement, fly ash or by the addition of chemicals such as polymers, resins and enzymes.
- Biological stabilization – refers to the planting of vegetative cover to prevent wind, water and soil erosion. The roots hold and aggregate soil particles together although in the beginning, other methods of stabilization should be used to support the growth of seeds and seedlings.
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 a single method or a combination of the two.
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What is the purpose of soil stabilization?
There are several reasons for it and these reasons include:
- Substituting poor grade soils with aggregates possessing more favourable engineering properties.
- Enhancement of the strength and therefore bearing capacity of the soil.
- Dust control for a good working environment.
- Waterproofing for conservation of natural or manmade structures.
- To promote the use of waste geomaterials in constructions.
- Finally, enhancing the properties of soil on site.
Not all sites offer favourable construction conditions. At such sites, a contractor usually has six main reasons why soil stabilization is needed as described above. Reasons 1, 2, 3 and 4 are more chemical and mechanical soil stabilization, whereas reason 5 is biological and mechanical stabilization. Today, with better research and more effective equipment and materials, soil stabilization for reason 6 involves choosing the best suitable technique which achieves the deliverables of the soil stabilization project according to prior cost-benefit analysis. Some definitions of soil stabilization also refer to the process as soil modification of steady or weak soil.
What are the benefits of Soil Stabilization?
- Offers erosion and sediment control and by controlling both we are attempting to maintain the most productive layer of the soil, the topsoil in place.
- Places barriers that prevent the movement of air and water over the soil that carry away soil particles.
- Makes weak or sub-optimal soil stronger.
- Facilitates keeping the soil intact, which facilitates the growth of plants that further helps in a more robust structure.
- Longer lasting results of soil stabilization in road construction have positive influence on the environment, saving energy, materials and equipment.
- Offers strength improvement including shearing strength and compressive strength
- Mitigates and reduces volume instability and swelling potential and controlling shrinkage
- Reduces plasticity index (PI)
- Reduces permeability
- Reduces soil compressibility, deformation and settlement
- Reduces clay/silt-sized particles
- Improves resilient modulus
- Improves durability to resist unfavourable environmental conditions such as freeze-thaw or wet-dry cycles, erosion and weathering
- Offers Dust control
- Offers Waterproofing
GRT’s Engineered Soil Solutions:
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.
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.
