In geotextile procurement, weight (expressed in g/m² or oz/yd²) and thickness (in mm or mils) are often the first numbers a buyer sees. They are convenient benchmarks. However, relying solely on these values for engineering decisions is a common and potentially costly mistake.
What Geotextile Weight Actually Tells You:
Mass per unit area is a physical property, not a performance property.
It is a useful quality control indicator: significant variation from the stated nominal weight may indicate production inconsistency.
Within the same product type (e.g., needle-punched non-wovens), weight broadly correlates with strength and puncture resistance—but this correlation is not linear and varies significantly by manufacturer and production process.
Weight alone cannot predict: tensile strength, elongation, AOS, permittivity, UV resistance, or long-term durability.
What Geotextile Thickness Actually Tells You:
Thickness (measured under a specified platen pressure per ASTM D5199) indicates the fabric's bulk.
For non-woven geotextiles, thickness influences:
Compressibility: How much the fabric thins under load.
Asphalt retention capacity (for paving fabrics).
Protection capacity: Thicker fabrics generally provide better cushioning for geomembranes.
For woven geotextiles, thickness is less relevant and often not specified.
The Critical Misconception:
Buyers sometimes specify "400gsm non-woven geotextile" as a blanket requirement. This is problematic because:
A 400gsm fabric from Manufacturer A may have 60% higher tensile strength and 40% better puncture resistance than a 400gsm fabric from Manufacturer B, depending on fiber quality, needle-punch density, and finishing.
Conversely, a 350gsm fabric from a high-quality producer may outperform a 450gsm fabric from a low-quality producer.
The Right Approach to Specification:
Never specify by weight alone. It invites the lowest-cost, potentially lowest-performance product that meets that number.
Specify performance properties: Minimum tensile strength (kN/m), minimum CBR puncture resistance (N), maximum AOS (mm), and minimum permittivity (s⁻¹).
Use weight as a reference or QC check, not a design parameter.
How HZGeotextile Helps:
We provide comprehensive geotextile data sheets showing the full suite of mechanical and hydraulic properties. We encourage engineers to design to these performance values, not just the GSM. This ensures you receive a fabric that is fit for purpose, not just "heavy."
For guidance on writing performance-based specifications, contact our engineering support team at www.hzgeotextile.com.
