Understanding Soil Stabilisation in Construction

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What is Soil Stabilisation?

Soil stabilisation is the process of improving the mechanical properties of soil to make it stronger, more stable, and resistant to erosion. This can be achieved through mechanical methods, chemical additives, or geosynthetic materials. It is commonly employed in construction projects, like building roads and retaining walls, to ensure a stable foundation. The aim is to establish a solid base capable of supporting the weight and stress of construction materials while withstanding erosion over time. The methods and materials chosen depend on the soil type and the construction project’s unique requirements.

Why Do We Need Soil Stabilisation?

  1. Prevent settling and subsidence: Without proper soil stabilisation, the subgrade can settle or subside over time, leading to pavement cracking and uneven surfaces.
  2. Control soil erosion: Soil stabilisation helps control soil erosion, which can weaken the subgrade and lead to pavement failure.
  3. Enhance load-bearing capacity: Soil stabilisation improves the load-bearing capacity of the subgrade, allowing it to better support the weight of vehicles and other traffic.
  4. Increase durability: Soil stabilisation enhances the durability of pavements by improving the stability of the subgrade and reducing the likelihood of pavement failures.
  5. Minimise maintenance costs: By improving the stability and strength of the subgrade, soil stabilisation can minimise the need for ongoing maintenance and repair of pavements, reducing maintenance costs over time.

Soil Stabilisation Methods

  1. Mechanical Stabilisation: The process of improving the physical properties of soil by physically altering its structure. This is typically achieved by compacting the soil, adding aggregate materials such as gravel, or mixing the soil with other materials. The goal of mechanical soil stabilisation is to increase the strength and stability of the soil, making it more suitable for construction purposes, such as laying a foundation or building a road. The method used will depend on the type of soil being stabilised and the specific needs of the construction project.
  2. Lime Stabilisation: a construction and soil engineering technique used to improve the properties of soil, making it more suitable for construction purposes. This process involves the addition of lime (usually in the form of quicklime or hydrated lime) to soil to modify its characteristics and enhance its engineering properties. Lime is a basic material that reacts with the clay particles in the soil to form calcium-silicate-hydrates (C-S-H) and calcium-aluminate-hydrates (C-A-H). These compounds are cementitious, which means they bind the soil particles together and increase the strength and stiffness of the soil.
  3. Cement Stabilisation: a soil improvement technique that involves mixing cement with soil to improve its engineering properties. The cement reacts with the water to form a paste that binds the soil particles together, increasing the strength and stiffness of the soil. It involves the addition of Portland cement, or a similar cementitious material/blend. The amount of cement required for cement stabilisation depends on the type of soil and the desired engineering properties. In general, the more cement that is used, the stronger and stiffer the soil will be. However, too much cement can make the soil brittle and more susceptible to cracking.
  4. Bituminous stabilisation: also known as bitumen stabilisation or asphalt stabilisation, is a construction and soil engineering technique that involves the addition of bitumen (commonly referred to as asphalt) to soil to improve its engineering properties and create a stable and durable base or sub-base for various infrastructure projects. This technique is commonly used in road construction, particularly for subgrade and sub-base layers. Bituminous stabilisation offers advantages such as increased strength, improved resistance to moisture, and enhanced durability.
  5. Chemical Stabilisation: The process of using chemical additives to improve the physical properties of soil, making it stronger, more stable, and resistant to erosion. This method is commonly used in construction, particularly in building roads and other infrastructure projects, to create a strong and durable foundation. The chemicals used in soil stabilisation vary depending on the type of soil being treated and the desired outcome. Common additives include cement, polymers, lime, and fly ash.
  6. Soil Stabilisation using Geosynthetics: The process of using a synthetic fabric material to reinforce and stabilise the soil. The geosynthetic material is placed between the soil and any construction material, such as asphalt or concrete, to prevent soil erosion and movement and distribute load and stress more evenly.
Soil stabilisation is important for enhancing the engineering quality of soil and increasing its bearing capacity, resistance to weathering, and permeability. Negi 2013 and Mudliar 2019 both suggest that soil stabilisation using lime and cement, respectively, can improve the geotechnical properties of soil, such as plasticity, compaction, and unconfined compressive strength. Amhadi 2018 provides an overview of different soil stabilisation methods, including mechanical and chemical stabilisation, which can increase the shear strength of soil and control its shrink-swell properties. Afrin 2017 also reviews different types of soil stabilisation techniques, emphasising the importance of changing the physico-synthetic properties of soil to reduce permeability and compressibility and increase shear strength. Overall, these papers collectively suggest that soil stabilisation is important for ensuring the stability and load-bearing capacity of soil in construction projects.
soil stabilisation construction-process
Renolith Soil Stabilisation

Renolith 2.0 is a patented nanopolymer admixture for creating high performance cementitious composites. It is typically used in soil stabilisation & pavement recycling applications, where it enhances the application process and significantly improves compressive & tensile strength, stiffness, durability and impermeability. It enables a low-cost method of constructing long-life pavements free of ruts, cracks and potholes. Most importantly, this nanotechnology eliminates cracking from drying shrinkage.

Renolith can help improve a project’s Infrastructure Sustainability (IS) Rating. It enables roads to be constructed using 100% in-situ soils and/or recycled aggregates, thereby eliminating the need to dispose of in-situ soils and mine, crush and transport vast quantities of virgin quarry material.

Renolith™ pavements are constructed using standard soil-cement stabilisation methods. To know more about the features and benefits of Renolith™ to your projects, visit our Product Page for more details.

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