Bangladesh University of Engineering and Technology
Department of Civil Engineering
Course Number: CE 342
Course Title: Geotechnical Engineering Laboratory
Term: January 2025
Course Teachers:
1. Dr. Md. Ferdous Alam
Associate Professor, Department of Civil Engineering, BUET
2. Ms. Sameeha Islam
Lecturer, Department of Civil Engineering, BUET
Name of the Assignment: Geotextile
Submitted by:
Name: Diganta Nandi
Student ID: 2104120
Level-3, Term-I
Section: B2
1. Introduction and Historical Development
Geotextiles are specially made textile materials that are important in modern geotechnical
engineering. They are permeable fabrics, either synthetic or natural, that, when placed in soil or
other civil engineering materials, provide functions like separation, filtration, drainage,
reinforcement, and protection. Their widespread use has opened up new possibilities for improving
soil stability, enhancing drainage, and increasing the durability of civil engineering structures.
The idea of using fibrous materials to improve ground performance goes back to ancient
constructions, such as the Great Wall of China. However, real innovation in geotextiles started in
the 20th century. The introduction of synthetic polymers in the 1950s and 1960s, like
polypropylene and polyester, marked a significant change. These materials offered better
durability, strength, and resistance to biological and chemical wear, allowing geotextiles to surpass
natural fiber options in tough conditions.
Geotextiles are made through two main processes: weaving and nonwoven bonding. Woven
geotextiles are created by interlacing yarns in a regular pattern, achieving high tensile strength and
low elongation. This makes them suitable for reinforcement and soil stabilization. In contrast,
nonwoven geotextiles are made by bonding synthetic fibers, resulting in highly permeable fabrics
that work well for filtration and drainage.
Today, geotextile applications are varied. They are used in road and railway foundations, landfill
barriers, erosion control, and coastal protection projects. Continuous improvements in
manufacturing and testing standards, along with the development of new types of geotextiles, such
as biodegradable and smart textiles, are expanding their effectiveness. As a result, geotextiles have
become essential for sustainable infrastructure development, providing technical and economic
benefits that are vital for modern civil engineering projects.
2. Geotextile Composition and Materials
2.1 Synthetic Polymers
The main materials used to make geotextiles are synthetic polymers. They provide excellent
durability, reliable properties, and resistance to biological breakdown. The four main types of
polymers used are:
• Polypropylene (PP): This is the most commonly used polymer for geotextiles.
Polypropylene is chemically inert, lightweight, and cost-effective. However, it is sensitive
to UV radiation and high temperatures, needing stabilizers for long outdoor exposure.
• Polyester (PET): Polyethylene terephthalate has better creep resistance and higher
strength compared to polypropylene. It performs well under high-stress conditions and
high temperatures but can break down in alkaline conditions that exceed pH 10.
• Polyethylene (PE): High-density polyethylene offers good chemical resistance and
flexibility but has higher creep compared to polyester and polypropylene.
• Polyamide (PA): Nylon-based geotextiles offer high strength and resistance to abrasion,
but they are prone to weathering.
2.2 Natural Fibers
Natural fiber geotextiles make up a smaller market segment but provide environmental benefits
like biodegradability and easy availability in developing countries.
Common natural fibers include:
• Jute: Known for its strong initial tensile strength and good water absorption.
• Coir: Offers great erosion control and moisture retention.
• Hemp, Sisal, and Flax: Each has varying strength and durability for temporary uses.
Natural fiber geotextiles are mainly used for short-term applications (2-3 years) where
biodegradation is beneficial, such as in slope stabilization and erosion control.
3. Types of Geotextiles
3.1 Classification by Manufacturing Process
Geotextiles are divided into several categories based on how they are made:
• Woven Geotextiles: Made by interlacing longitudinal and transverse yarns or filaments in
different weave patterns. They have high tensile strength, low elongation, and strong
reinforcement properties.
• Nonwoven Geotextiles: Created by bonding fibers or filaments through mechanical,
thermal, or chemical means without weaving. They provide excellent filtration and
drainage due to their three-dimensional structure and higher porosity.
• Knitted Geotextiles: Formed by interlocking yarn loops to make planar structures. These
materials are flexible and can adapt to uneven surfaces.
• Composite Geotextiles: Made by combining various fabric layers or materials to achieve
specific performance traits.
3.2 Nonwoven Geotextile Subcategories
Nonwoven geotextiles, which make up over 75% of the global market, are further categorized by
their bonding methods:
• Needle punched: Uses mechanical bonding with barbed needles.
• Spunbonded: Involves continuous filament deposition with thermal bonding.
• Heat-bonded: Involves thermal bonding of thermoplastic fibers.
• Chemically bonded: Uses adhesive bonding systems.
4. Functions of Geotextiles
Geotextiles serve multiple functions in geotechnical applications, often at the same time:
Primary Functions:
• Filtration: Keeps soil particles while allowing fluids to pass.
• Drainage: Collects and redirects fluid flow.
• Separation: Prevents different materials from mixing.
• Reinforcement: Adds tensile strength to soil systems.
Secondary Functions:
• Surfacing: Creates smooth, stable surfaces.
• Containment: Keeps materials in place.
• Protection: Cushions against physical damage.
5. Testing Methods and Experimental Procedures
The following sections describe the standardized testing methods used to evaluate geotextile
properties and performance.
5.1 Wide-Width Tensile Strength Test
Experiment Name: Wide-Width Tensile Strength Test
Test Standard: ISO 10319:2015 (formerly ISO 10319:2008), ASTM D4595-17
Procedure:
The test uses samples that are 200mm wide and 100mm long. Samples are conditioned at standard
atmospheric conditions before testing. The sample is held in pneumatic grips and tested for tensile
strength at a constant rate of extension (20 ± 2 mm/min) until it breaks. Load-extension data is
continuously recorded during the test.
Relevant Parameters:
• Maximum tensile load per unit width (KN/m)
• Strain at maximum load (%)
• Secant stiffness at 2%, 5%, and 10% strain
• Ultimate elongation at break
Significance of Test Parameters:
This test gives a representative measure of geotextile tensile properties under field conditions by
reducing boundary effects and necking. Secant stiffness values are crucial for reinforcement
design calculations, and ultimate strength determines the safety factor for structural applications.
5.2 Grab Tensile Strength Test
Experiment Name: Grab Tensile Strength Test
Test Standard: ASTM D4632-08
Procedure:
Samples measuring 101.6 mm × 203.2 mm are prepared with attention to fabric direction. The
sample is held in the middle area (25.4 mm × 50.8 mm) with a 75 mm gauge length between grips.
Testing is done at a rate of 300 mm/min until the sample fails.
Relevant Parameters:
Grab breaking load (N)
Elongation at break (mm)
Load-elongation curve characteristics
Significance of Test Parameters:
This test gives an index of the material's effective strength. It measures the strength of the fabric at
a specific width combined with strength contributions from adjacent materials. This test is
especially useful for quality control and comparing products with similar structures.
5.3 Puncture Resistance Test
Experiment Name: Index Puncture Resistance Test
Test Standard: ASTM D4833-07(2020), ASTM D6241-09 (CBR Puncture)
Procedure:
For ASTM D4833, samples with a minimum diameter of 100mm are placed between holding
plates of a puncture fixture. A steel rod with an 8mm diameter and 45° conical tip is pushed
through the center of the sample at 300 mm/min until it ruptures. The maximum force is recorded
as puncture resistance.
Relevant Parameters:
• Maximum puncture force (N)
• Energy to puncture (J)
• Displacement at maximum force
Significance of Test Parameters:
Puncture resistance shows how well the geotextile can withstand installation stresses and resist
damage from sharp particles. This feature is critical for its durability during construction and its
long-term performance under load.
5.4 Apparent Opening Size Test
Experiment Name: Apparent Opening Size Determination
Test Standard: ASTM D4751-21a
Procedure:
Spherical glass beads with known size distribution are passed through geotextile samples for 10
minutes at a controlled vibration frequency (110-115 oscillations/minute). The mass of beads
trapped by the geotextile is measured. The apparent opening size (O95) is calculated as the size
that retains 90% of the beads.
Relevant Parameters:
• Apparent opening size O95 (mm)
• Mass of glass beads retained
• Coefficient of uniformity of openings
Significance of Test Parameters:
The apparent opening size is important for filtration design because it determines how well the
geotextile can keep soil particles while allowing enough drainage. This directly affects filter
design and potential clogging.
5.5 Water Permeability Test
Experiment Name: Water Permeability Characteristics Normal to Plane
Test Standard: ISO 11058:2010, ASTM D4491-99a
Procedure:
Two methods are used: constant head and falling head. In the constant head method, water flows
through the geotextile under a steady hydraulic gradient of 50mm. The steady flow rate is
measured and converted to velocity index (VH50). The falling head method measures flow rate
under decreasing hydraulic head conditions.
Relevant Parameters:
• Velocity index VH50 (mm/s)
• Permittivity ψ (s⁻¹)
• Cross-plane hydraulic conductivity (m/s)
Significance of Test Parameters:
Water permeability characteristics tell how suitable the geotextile is for drainage and filtration.
The velocity index provides a standard measure for comparison, while permittivity values are vital
for hydraulic design calculations.
5.6 Creep Testing
Experiment Name: Tensile Creep and Creep-Rupture Testing
Test Standard: ASTM D5262-07, Accelerated Testing Methods
Procedure:
Samples are subjected to sustained tensile loads, usually ranging from 20-80% of ultimate tensile
strength, over long periods (1000+ hours). Load, elongation, temperature, and environmental
conditions are continuously monitored. Accelerated testing uses higher temperatures with time-
temperature principles.
Relevant Parameters:
• Creep strain vs. time relationships
• Creep modulus reduction factors
• Time to rupture at different load levels
• Isochronous stress-strain curves
Significance of Test Parameters:
Creep behavior is crucial for predicting long-term performance in reinforcement applications.
Creep reduction factors are important for design calculations to ensure adequate safety margins
throughout the design life.
5.7 Chemical Resistance Testing
Experiment Name: Chemical Resistance to Liquids
Test Standard: ASTM D6389-23, ISO 12960:2020
Procedure:
Geotextile samples are soaked in test liquids that represent expected service conditions for
specified periods (usually 30-120 days) at controlled temperatures. Testing before and after
exposure measures any changes in properties.
Relevant Parameters:
• Tensile strength retention (%)
• Mass change (%)
• Dimensional stability
• Visual assessment of degradation
Significance of Test Parameters:
Chemical resistance testing assesses long-term durability in harsh environments, like landfill
leachates and chemically contaminated soils. Retention values indicate how suitable the material is
for specific chemical conditions.
5.8 UV Resistance Testing
Experiment Name: Ultraviolet Light Exposure Testing
Test Standard: ASTM D4355-14, IS 13162-2:1991
Procedure:
Samples are exposed to xenon-arc light sources under controlled temperature and humidity.
Exposure times range from 150-500 hours depending on application needs. Testing before and
after exposure evaluates strength retention.
Relevant Parameters:
• Tensile strength retention after exposure (%)
• Visual assessment of surface degradation
• Color change measurements
• Exposure energy (MJ/m²)
Significance of Test Parameters:
UV resistance indicates how well the geotextile can keep its properties during installation and use
outside. Strength retention values help in choosing the right stabilization systems and installation
methods.
6. Applications in Geotechnical Engineering
6.1 Transportation Infrastructure
Geotextiles play important roles in building roads and railways. They stabilize subgrade materials,
separate base course materials, and improve drainage. Uses include paved and unpaved roads,
parking areas, railroad track stabilization, and airport runway construction.
6.2 Environmental Engineering
In environmental projects, geotextiles are used in landfill liners, leachate collection systems,
contaminated site cleanup, and waste containment facilities. They perform filtration, drainage, and
protection functions while being compatible with harsh chemicals.
6.3 Hydraulic Engineering
For water resource projects, geotextiles are important in dam construction, reservoir linings,
coastal protection systems, drainage systems, and erosion control structures. They provide
filtration under riprap protection, drainage for embankments, and separation in hydraulic systems.
6.4 Slope Stabilization and Reinforcement
Geotextiles are used to reinforce soil in steep slopes, retaining walls, and embankments over weak
foundations. Their tensile strength boosts the compressive strength of soil, creating stronger
composite systems that can handle more load.
7. Design Considerations and Performance Criteria
7.1 Filtration Design
Filtration design considers retention, permeability, and clogging. The relationship between the size
of the geotextile's pores and soil particle size affects how well it filters:
On ≤ A × dx
where On is the geotextile opening size, A is a factor based on soil and loading conditions, and dx
is the soil particle size.
7.2 Reinforcement Design
Reinforcement design looks at tensile strength needs, strain compatibility, and long-term creep
behavior. Design processes factor in safety margins, potential installation damage, creep
reduction, and chemical degradation effects.
7.3 Durability Assessment
To assess long-term performance, it's necessary to evaluate physical, chemical, and biological
durability. Environmental conditions, installation practices, and service loads all impact durability
requirements and safety factors.
8. Summary
This analysis of geotextile materials shows their key role in modern geotechnical engineering. The
shift from natural fibers to synthetic polymer systems has led to versatile materials that can
perform multiple functions at once. The use of polypropylene and polyester-based systems
highlights the balance between performance, durability, and cost.
The testing methods discussed in this report outline the thorough evaluation processes needed to
ensure proper performance in challenging geotechnical applications. From basic tests like grab
tensile strength to detailed assessments of long-term creep and chemical resistance, these standard
procedures support engineering design and quality assurance.
The multifunctional properties of geotextiles, which include filtration, drainage, separation, and
reinforcement, have changed the practice of geotechnical engineering by offering cost-effective
solutions to complex soil issues. Ongoing advances in manufacturing technologies, material
formulations, and testing methods will keep geotextiles essential for sustainable infrastructure.
Future developments in geotextile technology aim for better environmental compatibility with
biodegradable materials for temporary uses, smart geotextiles that can monitor conditions, and
high-performance composites for severe loads. Combining these innovations with traditional
geotechnical engineering principles will broaden the applications and effectiveness of geosynthetic
solutions in civil engineering.
9. References
1. Rawal, A., Shah, T., & Anand, S. (2010). Geotextiles: production, properties and
performance. Textile Progress, 42(3), 181-226.
2. Scielo - Energy-efficient urban buildings (2020)
3. MDPI - Energy-Efficient Geopolymer Composites (2024)
4. Wiley - On the Composition of LiNi0.5Mn1.5O4 Cathode Active Materials (2023)
5. MDPI - New Types and Dosages for Low-Energy Cements (2023)
6. MDPI - Influence of Different Types of Cemented Carbide Blades (2021)
7. MDPI - The Effects of Seawater Treatment on Selected Coniferous Wood Types
(2023)
8. MDPI - Complex-Phase Steel Microstructure Segmentation (2023)
9. MDPI - Responses of Melilotus officinalis Growth (2019)
10. Nature - Composition and phase engineering of metal chalcogenides (2022)
11. MDPI - Removal of Organic Dyes, Polymers and Surfactants (2024)
12. Ocean Geosynthetics - 5 Types of Geotextiles, Functions & Its Uses (2023)
13. ISO - ISO 10319:2008 (2015)
14. Number Analytics - Geotextiles in Geotechnical Engineering (2025)
15. Palmetto Industries - Types of Geotextiles: 11 Types Explained (2025)
16. ISO - ISO 12960:2020 (2020)
17. PubMed - Review of Application and Innovation of Geotextiles (2020)
18. BJ Geotextile - Geo Fabric Types, Functions, Benefits (2022)
19. Textile Sphere - Test methods of Geotextiles (2020)
20. PMC - Review of Application and Innovation of Geotextiles (2020)
21. WinFab - Types of Geotextiles Fabrics - Functions and Applications (2022)
