Technical Guide: PP vs PET Geotextiles
Polypropylene (PP) and Polyester (PET) are the two most common polymers used in nonwoven geotextiles. While both can meet performance requirements, the more practical starting point for selection is often the application itself.
This guide compares PP and PET across key technical areas but ultimately aims to help you choose the right material based on site-specific needs — whether it's drainage, filtration, or resistance to aggressive soil conditions.
1. Polymer Structure & Manufacturing
- PP Geotextiles
- Made from polypropylene staple fibres
- Typically needle-punched
- Lower density
- PET Geotextiles
- Made from continuous filament polyester
- Usually needle-punched and thermally bonded
- Higher density
2. Mechanical Performance
|
Property |
600gsm PP |
600gsm PET |
|
Tensile Strength |
2200 N |
2500 N |
|
Grab Tensile Strength |
6000 N |
7000 N |
|
CBR Puncture Strength |
60% |
60% |
|
Elongation |
~60% |
~60% |
PET geotextiles typically demonstrate higher tensile and puncture strength than PP. This is due to PET’s stiffer molecular structure and higher modulus, making it a stronger and more cost-effective option at equal weights.
3. Hydraulic Properties
|
Property |
600gsm PP |
600gsm PET |
|
Pore Size (O90) |
60 µm |
70 µm |
|
Water Flow Rate (Q100) |
95 L/m²/s |
80 L/m²/s |
This side-by-side comparison shows that PET geotextiles at the same GSM often provide higher water flow rates due to their more open structure and thermal bonding. PP still offers finer filtration, which is useful for projects requiring sediment control or containment performance in fine soils.
4. Environmental Resistance
|
Condition |
PP |
PET |
|
UV Resistance |
Requires additives |
Inherently more resistant |
|
Chemical Resistance |
Excellent in alkaline |
Better in acidic |
|
Temperature Stability |
Up to ~120°C |
Up to ~200°C |
|
Water Absorption |
None (hydrophobic) |
Minimal |
|
Wet-Dry Cycling |
Performs stably after long-term exposure when buried |
Performs stably after long-term exposure when buried |
PET provides better UV and thermal resistance; PP is ideal for chemically aggressive high alakaline soils.
5. Recommended Applications
|
Application Type |
Preferred Material |
|
Subsoil drainage & wrapped drains |
PET |
|
Filtration in fine soils |
PP |
|
High-temperature or UV-exposed surfaces |
PET |
|
Alkaline tailings or marine exposure |
PP |
|
Landfill capping or reinforcement |
Either (grade dependent) |
6. Choosing Based on Application
In practice, PET is the more common choice across civil and drainage applications in Australia. Its higher strength-to-weight ratio, lower cost per square metre, and better UV/thermal performance make it the default option unless the project has specific conditions requiring PP.
PP is usually not interchangeable — it is selected when chemical conditions (e.g. high alkalinity) or filtration demands make PET unsuitable. Even then, PET often remains more economical even when comparing GSM-to-GSM. For instance, while 1000gsm PP might be specified as a substitute for 1200gsm PET in certain use cases, PET still provides greater tensile strength and UV stability at equal weights.
Common PET-based products in Australia include Bidim® and Texcel®. Our InfraThread® series is used across Australian and Pacific projects and offers civil-grade performance in both polymer types.
Our Recommendation
At Infratex, we offer the InfraThread® series of high-performance nonwoven geotextiles in both PP and PET options. Whether you're working on roadworks, drainage layers, or landfill containment, our InfraThread range is engineered to meet Australian conditions with robust mechanical and hydraulic performance.
- InfraThread® PP: Ideal for alkaline or marine environments and fine soil filtration
- InfraThread® PET: Preferred for drainage, thermal exposure, and high UV resistance
For help selecting the best grade for your project, contact our team for specification support.
