1.3.

Need for Stabilization

Soil stabilization is a technique to refine and improve the engineering properties of soils such as
mechanical strength, permeability, compressibility, durability and plasticity properties of soil to make it suitable
for construction. The need for soil stabilization arises primarily due to the presence of weak or problematic soils,
such as expansive clays that swell and shrink with moisture changes, or loose sandy soils with poor shear
strength, both of which can lead to structural failures if untreated.
In civil engineering structures, various kinds of soils are used; however, some soil deposits in their natural form
are suitable for construction purposes, whereas others are unsuitable without treatment, such as the problematic
soils. These soils need to be excavated and then replaced, or their properties should be modified before they can
sustain the applied loads by the upper structures. Typical of problematic soils are the expansive soils, which are
frequently observed due to their existence worldwide, except the arctic regions. Expansive soils are problematic
due to the performances of their clay mineral constituent, which makes them exhibit the shrink-swell
characteristics. The shrink-swell behaviours make expansive soils inappropriate for direct engineering
application in their natural form. In an attempt to make them more feasible for construction purposes, numerous
materials and techniques have been used to stabilise the soil.
Due to the adverse nature of expansive soil, geotechnical engineers are persistently searching for various options
to mitigate its objectionable characteristics via soil stabilisation technologies. The aim of the engineers in
stabilisation of expansive soil is more or less to normalise the volume change and plasticity or workability
characteristics, whilst significantly improve the strength properties. Soil stabilization with chemical admixtures
is beneficial in many aspects such as enhancing shear strength and compressive strength, mitigating and
reducing volume instability and swelling potential and controlling shrinkage, reducing the plasticity index, soil
compressibility, deformation, and settlement.

Infrastructure projects, including roads and building foundations, often require stabilization to ensure long-term
stability and prevent excessive settlement or pavement cracking. Beyond improving soil strength, stabilization
offers economic and environmental benefits by reducing the need for costly soil replacement and enabling the
use of sustainable materials like fly ash and slag, polymers, fibres, waste/recycled materials (e.g., shredded tire,
crushed glass, etc.). Various techniques are employed, including mechanical methods like compaction, chemical
treatments using lime or cement. Soil stabilization is widely used in many civil engineering applications such as
sub-base and sub-grade construction, rail and road construction, foundation construction and embankments,
backfill for bridge abutments and retaining walls, etc.

1.4. Advantages of soil Stabilization

Soil stabilization offers a wide range of advantages, making it a vital technique in modern geotechnical
engineering and construction. According to various researches, one of the primary benefits of soil stabilization is
the enhancement of soil strength and stability. By stabilizing soils that are otherwise weak, expansive, or prone
to erosion, this process provides a stronger and more durable foundation for construction projects, such as roads,
buildings, and pavements. Stabilized soil exhibits improved load-bearing capacity, reduced plasticity, and
increased resistance to water infiltration, which significantly reduces the risk of structural failure and enhances
long-term performance.
Moreover, soil stabilization can lead to significant cost savings. Rather than relying on costly imported
materials, local soils can be treated with stabilizing agents such as cement, lime, or industrial by-products like
fly ash, waste glass, brick powder. This makes the process both environmentally and economically beneficial,
particularly in areas where high-quality soil is scarce. Stabilized soil is also more durable and less prone to
erosion or deformation, which reduces maintenance costs over time. The soil stabilization leads to increase the
bearing capabilities, be resistant to volume change, improvement in dry unit weight to reinforce road surfaces
and other geotechnical applications.

While also addressing environmental concerns related to waste disposal, The use of waste materials, such as fly
ash, waste glass and slag, for soil stabilization not only improves the soil’s properties but also helps in the
disposal of industrial by-products, contributing to sustainable construction practices. Furthermore, biological
stabilization methods, like using plant roots or natural enzymes, offer eco-friendly alternatives for preventing
soil erosion and improving soil structure without relying on chemicals. The versatility of stabilization methods
allows for tailored solutions depending on soil type, climate, and project requirements, making it a highly
adaptable and effective solution in a wide variety of construction scenarios.

1.5. Applications of soil Stabilization

Soil stabilization has diverse applications across various fields of civil engineering, as highlighted in numerous
research papers. One of the most common applications is in road construction, where stabilized soil serves as a
durable base material, enhancing load-bearing capacity, reducing erosion, and extending the lifespan of
pavements. In foundation engineering, stabilized soil is used to improve the strength and stability of building
foundations, particularly in areas with weak or expansive soils. Additionally, soil stabilization plays a crucial
role in slope stabilization, preventing soil erosion and landslides in hilly or mountainous areas, while also
facilitating the development of sustainable embankments. Airport runways and railway tracks benefit from
stabilized soil due to its ability to provide a robust and resilient subgrade that can withstand heavy traffic loads.
In agricultural land reclamation, stabilization techniques help improve the fertility and structural integrity of
soil, making it more suitable for cultivation. Moreover, the use of biological stabilization methods, such as
planting vegetation or applying natural enzymes, is gaining attention for environmentally sustainable projects
like erosion control and landscaping. These applications underscore the multifaceted benefits of soil
stabilization in enhancing infrastructure resilience, reducing costs, and promoting sustainable development in
construction and environmental management. Some of the major applications are listed as:

 Road Construction: Improves the load-bearing capacity, reduces erosion, and extends pavement
lifespan.
 Foundation Engineering: Enhances strength and stability of foundations, particularly in weak or
expansive soils.
 Slope Stabilization: Prevents soil erosion and landslides, aiding in the development of sustainable
embankments.
 Airport Runways: Provides a resilient subgrade to withstand heavy traffic loads and environmental
stresses and ensures the stability of the runway under heavy loads and extreme weather conditions.
 Railway Tracks: Stabilized soil offers a strong, durable base to ensure the integrity of railbed
foundations and enhances resistance to track movement and deformation under load.
  Agricultural Land Reclamation: Improves soil fertility and structural integrity for better cultivation.
 Erosion Control: Prevents soil erosion in areas prone to water and wind forces.

1.6. Materials
The materials used in this study for soil stabilization include waste glass powder, surkhi, and kaolinite clay.
These materials were selected due to their availability, environmental sustainability, and their potential to
enhance the engineering properties of soil. Using waste glass powder, Surkhi (crushed brick) in kaolinite clay
will enhance and improve various soil properties like shear strength, shrinkage/swelling, plasticity index,
unconfined compressive strength and overall stability. These materials can be used as stabilizers to improve the
performance of subgrade soils in various construction projects. Waste glass powder, in particular, can act as a
pozzolanic material, increasing the strength of the soil when mixed with it. The chemical composition and
particle size distribution of these materials were carefully analyzed to ensure their suitability for the stabilization
process. Waste glass powder, surkhi, and kaolinite clay all exhibited specific pozzolanic properties that could
contribute to the improvement of the soil’s physical and mechanical characteristics.

1.6.1. Waste Glass powder: Waste glass powder (WGP) is a byproduct of recycling processes and typically
consists of finely ground glass particles. The use of WGP in soil stabilization is gaining attention due to its
potential to improve soil strength, reduce plasticity, and enhance durability. Glass, being a silicate material,
provides a beneficial pozzolanic effect when mixed with soil, promoting chemical reactions that enhance the
mechanical properties of the stabilized soil. In this study, waste glass powder was ground to a fine particle size
and used as a partial replacement for the natural soil to observe its effects on soil compaction, strength, and
permeability.
The waste glass materials used in this research were collected from local areas. The waste glasses were cleared
from dust and other toxic materials, and manually crushed into suitable sizes. After crushing the glasses to
eligible pieces, they were put in a rolling mill machine to transform them into powder.
Waste glass powder is derived from recycled glass and consists primarily of silica (SiO₂) but also contains other
oxides depending on the type of glass. The typical chemical composition of waste glass powder is as follows:

CaO 45- 55%, SiO2 12- 18%, MgO 3-8%, Al2O3 4–7%, Ferric oxide and inorganic compounds 12 %. Others
(trace elements): Small amounts of other metal oxides such as zinc, barium, and lead may also be present
depending on the glass type (e.g., clear glass, colored glass).

The high content of silica in waste glass powder provides its pozzolanic activity, making it effective in
improving the soil's strength when mixed.

1.6.2. Surkhi: Surkhi, also known as burnt clay or powdered brick, is an ancient material used in construction
for soil stabilization. It is derived from the calcination of clay or brick waste at high temperatures. It is red in
hue and has a delicate texture. It has significant power to minimise the swelling potential of black cotton soil.
Surkhi is rich in silica and alumina, making it a highly effective pozzolanic material that reacts with lime and
other binding agents to enhance the soil's cohesion and shear strength. In this research, surkhi was used in
varying proportions to determine its impact on the soil's geotechnical properties, such as compressive strength,
shear strength, and workability.
The chemical composition of surkhi varies depending on the raw material but typically includes the following:
Alumina 20% to 30% 2 Silica 50% to 60% 3 Lime 5% 4 Oxide of iron 5% to 6% 5 Magnesia 2% to 3%. Others
(trace elements): Small quantities of titanium oxide (TiO₂) and other trace elements may also be present.

The presence of silica and alumina in surkhi, along with its amorphous structure, enables it to function as a
pozzolanic material, reacting with lime to form cementitious compounds that improve the strength and
durability of the stabilized soil.

1.6.3. Kaolinite Clay: Kaolinite is a type of alumino-silicate clay mineral that is abundant in nature and often
used in soil stabilization due to its favorable properties, such as fine particle size, high plasticity, and excellent
workability. Kaolinite's chemical composition primarily consists of silica (SiO₂) and alumina (Al₂O₃), along
with a small amount of water and other minor components. The clay mineral is termed Kaolinite which has
Al2Si2O5(OH)4 as its chemical composition. Kaolinite Clay is very much important as an industrial mineral.
Kaolinite is a layered mineral of silicate coupled with silica which is SiO4, this is further linked through the
oxygen atoms to an octahedral sheet of the alumina (AlO6) octahedra.Rocks that are rich in kaolinite are called
the kaolin or also known as China Clay.
The dominant components, silica and alumina, contribute to the clay’s pozzolanic behavior. When mixed with
stabilizing agents (such as lime or other materials like waste glass powder or surkhi), kaolinite can help enhance
the cohesion and strength of the soil. The interlayer water in kaolinite plays a crucial role in determining its
plasticity and workability. This characteristic makes it particularly effective in controlling shrinkage and
improving the overall durability of the stabilized soil.