Geogrid Material Selection Guide: Biaxial vs Steel-Plastic vs PET

Choosing the right geogrid material is just as important as choosing the right production equipment. The material determines the mechanical properties, durability, cost, and ultimately the success of the project. But for many buyers — especially those new to geosynthetics — the options can be confusing.

This guide compares the three most common geogrid types: biaxial PP geogrid, steel-plastic composite geogrid, and PET geogrid. We cover material properties, how each one is manufactured, and which applications each is best suited for.

1. Quick Comparison Table

2. Biaxial PP Geogrid

Manufacturing process: Biaxial PP geogrid is produced by extruding a PP sheet, punching a regular hole pattern, and then biaxially stretching it in both machine and transverse directions. This process aligns the PP molecular chains, creating a high-strength, low-elongation grid structure. The manufacturing equipment — a biaxial injection geogrid line with 43 injection heads and 6-meter working width — produces grids in roll widths up to 6m.

Key properties:

• Strength range: 30/30 kN/m up to 120/120 kN/m (MD/TD)
• Elongation: ≤12%
• Aperture: 33×33 mm to 44×44 mm
• UV stabilized for outdoor exposure

Best applications: Road base reinforcement, railway subgrade, slope stabilization, embankment reinforcement. Biaxial geogrid is the most commonly used type for general civil engineering because it offers a good balance of strength, cost, and ease of handling.

3. Steel-Plastic Composite Geogrid

Manufacturing process: Steel-plastic geogrid is made by extruding HDPE over high-tensile steel wires to form composite strips, which are then ultrasonically welded into a grid pattern. The production line — a steel-plastic strip extrusion line (Ø90 extruder, 30:1 L/D, 10–60 m/min) combined with a 48-head ultrasonic welding line — produces grids with ultra-high strength and virtually zero elongation.

Key properties:

• Strength range: 80/80 kN/m up to 200/200 kN/m
• Elongation: ≤3% (extremely low — the steel wire takes the load)
• HDPE coating provides corrosion protection
• Node strength: ≥90% of parent material (ultrasonic welded)

Best applications: Heavy-duty road construction, mining roads, high fill embankments, industrial yards, port areas, and any project requiring very high tensile strength with minimal deformation. Steel-plastic geogrid is the go-to choice for extreme load conditions.

4. PET Geogrid

Manufacturing process: PET geogrid is manufactured by weaving or knitting high-tenacity polyester yarns into a grid structure, then coating for protection. When produced on a fiber geogrid welding line (6m weld width, 100–210 m²/h), the yarns are vibration friction welded at intersections using 20kHz ultrasonic frequency — which delivers optimal bonding results for PET fibers.

Key properties:

• Strength range: 50/50 kN/m up to 100/100 kN/m
• Elongation: ≤12%
• Very low creep over time (better long-term performance under sustained load)
• Coated for better soil adhesion and UV protection

Best applications: High retaining walls, steep slope reinforcement, bridge approaches, and reinforced soil structures where long-term creep performance is critical. PET geogrid is preferred when the structure must maintain its geometry over decades.

5. How to Choose: Decision Framework

Use this simple decision tree to narrow down your choice:

6. Cost vs. Performance

As a rough guideline, for equivalent tensile strength:

• Biaxial PP geogrid — Lowest material cost. Best value for standard applications.
• Steel-plastic geogrid — Higher material cost, but unmatched strength and stiffness. Justified by reduced fill thickness and longer service life in heavy-load applications.
• PET geogrid — Mid-range cost. The premium over biaxial is justified by long-term creep performance for critical structures.

The total installed cost also depends on the equipment used to produce the geogrid. In-house production (like CDXLI's own lines) eliminates middleman markup and allows custom roll sizes, which can reduce waste and installation time on site.

7. Summary

If you are specifying geogrid for an upcoming project, the most important first step is to determine the required tensile strength and allowable elongation for your design. From there, the choice between PP, steel-plastic, and PET becomes straightforward. And if you need technical support or mill test certificates, manufacturers with in-house production lines (like CDXLI) can provide real data — not just catalogue numbers.