Introduction
Nonwoven geotextiles have been utilized since the 1960s in civil engineering for applications such as separation, filtration, protection, and drainage. Numerous guidelines have been established to aid in project-specific specifications and product selection based on performance requirements.

Nonwoven Geotextile Manufacturing
Nonwoven geotextiles are characterized by their structure, bonding method, and raw materials, primarily polypropylene (PP) and polyester (PET). They are manufactured by bonding loose fibers or continuous filament layers through mechanical (needle punching) or thermal processes.

Needlepunching/Mechanical Bonding
This process involves entangling fibers into a three-dimensional structure using barbed needles, resulting in strong, flexible, and abrasion-resistant nonwovens. Products like Secutex® and Terrafix® are examples of mechanically bonded geotextiles.

Thermal/Cohesive Bonding
In this method, fibers are thermally bonded, creating a thin, less flexible nonwoven with a smooth surface. These nonwovens have lower elongation characteristics compared to needle-punched ones.

Strength Properties
Needle-punched nonwovens exhibit high elongation characteristics, making them more resistant to punctures and capable of accommodating soil irregularities better than thermally bonded or woven geotextiles.

Filter Properties
Needle-punched nonwovens are suitable for filtration due to their thickness and opening size ratio. They maintain long-term filter effectiveness and have superior water permeability compared to thermally bonded nonwovens.

Shear Properties
Needle-punched nonwovens achieve higher interface friction angles with adjacent soils due to their multi-dimensional surface structure, enhancing their performance in various applications.

Conclusion
Needle-punched nonwovens are robust and versatile, suitable for harsh conditions and various geotechnical fields. They offer superior long-term filtration and higher interface friction angles, proving effective in landfill engineering and other applications.