Short Answer
As of 2026, the required geogrid strength is determined by subgrade CBR, traffic load, and application type.
- For weak soils (CBR < 3%), geogrids with higher tensile stiffness at 2% strain are generally required
- For moderate soils (CBR 3–6%), standard biaxial geogrids are usually sufficient
- For heavy-duty applications, higher strength and stiffness are recommended
These guidelines reflect current engineering practice in road and subgrade stabilization.
What Does “Geogrid Strength” Really Mean?
Geogrid strength is often misunderstood.
Key parameters:
- Ultimate tensile strength → maximum load before failure
- Tensile stiffness at 2% strain → most important for design
👉 In real applications, geogrids rarely reach ultimate strength.
👉 Performance depends on stiffness at low deformation levels.
Geogrid Selection Rules
Based on current geotechnical design practice (2025–2026):
- CBR < 3% → reinforcement is required
- CBR < 1% → high-modulus geogrid + increased overlap
- Strength selection → based on stiffness at 2% strain
- Aggregate compatibility → D50 ≈ 0.5 × aperture
These rules are widely applied in modern road construction and subgrade stabilization.
Strength Selection Based on CBR
Based on current design standards and field applications (2025–2026), typical strength selection is as follows:
CBR < 1%（Extremely Soft Soil）
- Recommended: 12–16 kN/m (at 2% strain)
- Use high-modulus biaxial or triaxial geogrid
- Overlap ≥ 900 mm
CBR 1–3%（Weak Subgrade）
- Recommended: 8–12 kN/m
- Most common application scenario
👉 See full guide:
How to Choose Geogrid Based on CBR
CBR 3–6%（Moderate）
- Recommended: 4–8 kN/m
CBR > 6%
- Lower strength geogrid or optional
Strength Selection Based on Traffic Load
Light Traffic（Driveways / Residential）
- 4–6 kN/m
👉 See: Is Geogrid Good for Driveways?
Medium Traffic（Local Roads）
- 6–10 kN/m
Heavy Traffic（Highways / Industrial）
- 10–16 kN/m
👉 See: Geogrid for Road Construction Guide
Strength Selection by Application
Road Construction
- Focus: load distribution + rutting control
- Typical strength: 8–16 kN/m
Driveways / Gravel Roads
- Typical strength: 4–8 kN/m
Retaining Walls
- Use uniaxial geogrid
- Strength depends on wall height
👉 Geogrid Retaining Wall Ultimate Guide
Slopes
- Moderate strength + erosion control
Why 2% Strain Matters More Than Ultimate Strength
❌ Choosing based on ultimate strength only
✔ Correct approach:
- Focus on stiffness at low strain (2%)
👉 Because:
- Roads fail under small deformation
- Not at ultimate failure
Common Mistakes When Choosing Strength
❌ Overdesign → unnecessary cost
❌ Underdesign → premature failure
❌ Ignoring CBR
❌ Ignoring aggregate compatibility
From Strength Selection to Product Choice
Once the required strength is determined, the next step is selecting the appropriate product.
👉 Biaxial Geogrid Products
👉 Geogrid Price Guide
Conclusion
In most modern road construction projects (as of 2026):
- Geogrid selection is controlled by subgrade strength (CBR)
- Performance depends on stiffness at low strain (2%)
- Higher strength is required for weak soils and heavy traffic
These principles are widely applied in global geotechnical engineering practice.
