How is soil stabilization for road construction done?
Soil stabilization involves altering the natural properties of soil to improve its engineering performance. The process can include mechanical, chemical, or biological methods. These techniques use materials such as cement, chemical additives, or other agents to enhance the soil’s strength and stability.
The base is a critical part of road construction, as it transfers traffic loads to the underlying soil. The long-term performance of pavement structures depends on the stability of the underlying soil. Natural soils often lack the required engineering properties in their natural state. Thus, soil stabilization is necessary to modify these soils for construction.
What are the benefits of soil stabilization?
1. Increased bearing capacity with marginal soil infills:
Soil stabilization strengthens poor-quality soil which supports heavier loads. This eliminates the need for costly high-quality aggregates. Additives such as binders and aggregates act as binding agents, improving the subgrade’s load-bearing capacity. By utilizing the existing soil, construction becomes not only more sustainable but also more efficient, all while cutting down on material waste.
2. Improved durability:
Stabilized soils resist degradation from traffic and environmental factors. Consequently, roads enjoy a longer lifespan, fewer repairs, and reduced costs. The added strength and stability mean surfaces last longer, even under demanding conditions. This allows you to expect consistent performance and invest less in time and money on costly maintenance.
3. Moisture control:
Soil stabilization helps regulate moisture levels within the subgrade. This minimizes shrinking and swelling caused by moisture fluctuations. Stabilization may be obtained by the addition of drying agents or by modification of soil properties to provide a more balanced and sound foundation.
4. Erosion control:
Unstabilized soils can erode because of factors like wind, rain, and traffic. Stabilization binds soil particles, reducing detachment risks. This helps reduce sedimentation in waterways caused by erosion. This method also serves to reduce sedimentation in water bodies brought about by erosion, a huge advantage for conservation of the environment. Stabilized soils retain their form even during harsh weather, so fewer emergency repairs are required.
5. Extended maintenance cycle:
Soil stabilization improves the road’s durability. Stabilized roads are less prone to issues like potholes and cracks, leading to fewer repairs and cost savings. With less maintenance disruption, roadways can provide better service and safety for extended periods. This not only boosts the functional value but also the economic value of the infrastructure.
6. Cost efficiency:
Soil stabilization offers a cost-effective alternative to the traditional “dig-and-dump” methods. Considerable savings can be achieved by using on-site soil and reducing the need for imported aggregates. Lower disposal fees for unsuitable soils and reduced transportation costs further enhance project efficiency.
7. Environmental impact:
Soil stabilization offers significant environmental benefits. Stabilized soils reduce the carbon footprint by minimizing the need for extracting and transporting virgin materials. It also controls erosion, protects waterways from sedimentation, and preserves ecological health. Roads constructed on stabilized soils also improve the air quality because they do not produce as much dust.
What is the nature of soil?
Soil is a natural mixture of weathered rock, organic matter, minerals, air, and water. Its composition varies due to climate, parent rock, and other factors. Therefore, it becomes paramount to understand the nature of soil due to its complex nature and how it influences a construction project.
Clay soil
Clay is a fine-grained soil type composed primarily of particles smaller than 2 micrometers in diameter, known as clay minerals. Clay is high in plasticity, meaning it can be molded when moist but becomes hard and brittle upon drying. Clayey soils have a high affinity for water, leading to changes in volume with fluctuations in moisture content.
Clay mineralogy
Clay mineralogy relates to the specific types of clay minerals present in soil. The specific type of clay mineral (kaolinite, illite, smectite) affects how the clay behaves due to variations in its chemical makeup. For instance, smectite clays exhibit higher swelling potential compared to kaolinite clays due to their unique crystal structure.
Cement
Cement is a binding material commonly used in construction. When mixed with water, cement undergoes a chemical reaction called hydration, forming a strong, rigid paste that binds particles together. In soil stabilization, cement improves the strength, durability, and water resistance of the soil.
Salt
Sodium chloride (salt) has limited applications in soil stabilization, as its effectiveness depends on soil type and moisture conditions. It can improve the strength of some fine-grained soils, however, its efficacy depends on the soil type and moisture conditions. Salt can be corrosive to steel reinforcement and may not be suitable for all construction projects due to environmental concerns.
Brick dust
Brick dust (crushed or ground recycled brick material) can be used as a low-cost alternative to virgin aggregates in some soil stabilization projects. When combined with other stabilizing agents like cement or lime, the strength and drainage properties are highly improved. Brick dust’s effectiveness in improving soil properties varies depending on soil type, moisture conditions, and the quantity used. Using brick dust as a soil stabilizer can help reduce industrial waste and minimize the carbon footprint of construction projects.
What are the methods of soil stabilization?
Soil stabilization techniques are categorized into three main groups: mechanical, chemical, and biological. Each method offers its advantages and applications depending on the specific soil conditions and requirements of the project.
Mechanical methods:
Mechanical stabilization involves physically altering the soil structure to enhance its properties.
- Compaction: Compaction constitutes expelling air voids to physically densify the soil. This boosts the soil’s bearing capacity by reducing its volume and increasing internal friction between particles. Common compaction practices include dynamic compaction (repeatedly dropping a heavy weight) and vibro compaction (compaction using vibrations).
- Blending: Blending involves mixing different soil types with varying particle sizes to improve soil strength and structure. Due to the fine-grained materials like silts or clays being added to non-cohesive soils, the strength of the soil is greatly improved.
- Reinforcement: Geosynthetics or natural/synthetic fibers are often employed to reinforce the soil. When placed within the soil, geosynthetics restrict its movement which creates a more confined layer. This confinement improves the soil’s bearing capacity and tensile strength.
Chemical methods:
Introducing chemical additives that react with the soil to modify its properties is termed the chemical stabilization of soil. These additives bind soil particles together, augment strength, and alter water resistance.
- Cement: Owing to its easy availability and effectiveness with other materials, cement is a popular choice as a soil stabilizer. The successful application of cement as a stabilizer requires control of both cement and water content. The ideal mix ascertains complete cement hydration without compromising final density.
- Lime: Lime stabilization is particularly effective for clayey soils with moderate to high plasticity. It changes the soil’s properties by adding lime which triggers a chemical reaction. This technique is most useful when the correct amount of lime is used to stimulate ion exchange.
- Fly ash stabilization: Fly ash can be utilized as a binding agent to strengthen soil. It is mixed into the soil, where it reacts and supplements strength. Fly ash offers lower costs and can be used in high-moisture soils because of its drying effect.
Biological methods:
The biological stabilization of soil makes use of natural processes to boost soil properties, primarily for erosion control. It involves planting vegetation whose root systems improve long-term soil cohesion and reduce vulnerability to erosion.
What measures does Strata Geosystems take for soil stabilization?
In roadway improvement projects, unstable subgrade soils pose serious hurdles. Strata tackles these challenges with its array of geosynthetics solutions like StrataWeb geocell and StrataGrid uniaxial geogrid. StrataWeb and StrataGrid work by reinforcing the subgrade, creating a more sturdy foundation for the roadway. These geosynthetics reduce the need for thick base and sub-base layers, significantly saving on construction costs.
StrataWeb geocell features a unique honeycomb-like structure that excels at confining infill material. This reduces movement and lateral spreading, resulting in better load support and slope erosion resistance. The clients enjoy the multiple configurations offered by StrataWeb®, including deep texturing and engineered perforations, to optimize drainage within the infill material. StrataWeb® can be tailor-made for specific project requirements and features a collapsible design for easy transport and deployment.
StrataGrid boasts an exceptional tensile strength and reinforces soil in both vertical and horizontal directions. It is manufactured from high-tenacity polyester yarns. A UV-stabilized coating ensures long-lasting performance even in harsh weather. Notably, StrataGrid exhibits minimal elongation, providing reliable soil reinforcement for the best slope stability.
Strata’s soil stabilization solutions have improved projects globally
Innovative soil stabilization in Aamby Valley with StrataWeb® geocells
In the high-rainfall zone- Aamby Valley, it was observed that the eroding soil threatened nearby structures. Traditional retaining wall constructions were not viable due to time constraints. Strata provided a rapid solution using StrataWeb® geocells to contain the ground and support the building foundations. The proposed gravity wall consisted of in-filled geocell panels stacked one on top of the other. The bottom layers were spread out using steel spikes and compacted with a vibratory plate tamper. The geocell structure efficiently reinforced the soil and prevented further erosion. A tiered structure of the wall created a natural-looking ledge that was suitable for the growth of vegetation, while the StrataWeb® system made sure the structure was no longer vulnerable to heavy rainfall. This project demonstrates StrataWeb® geocells’ efficiency in providing rapid, economical, and aesthetically pleasing soil stabilization.
Technocraft Industries yarn mill roads strengthened with StrataWeb® geocells
In Amravati, India, Technocraft Industries encountered a serious hurdle during the construction of their new yarn mill’s internal road network. The expansive soil on-site posed a challenge for creating a strong pavement foundation as it was prone to movement. Strata’s geotechnical experts recommended using StrataWeb geocell for foundation reinforcement to improve the load-bearing capacity of the weak soil. The geocells confined the soil with ease due to its three-dimensional structure, distributing the load to a wider area and reducing stresses on the overall crust thickness. It also ensured the longevity of the pavement by reinforcing soil within. The ease of installation of StrataWeb® streamlined work execution, offering a cost-effective alternative to the conventional 200 mm concrete GSB.
Strata Geosystems offers cost-effective, durable, and eco-friendly soil stabilization solutions designed for long-lasting performance. Their modular products ensure faster installation, reduced material use, and minimal maintenance. Partner with Strata for expert-engineered geosynthetics and customized project support.