Geogrid Installation Guide

Compliant with ASTM D6637, AASHTO R 9 & FHWA-NHI-16-009

‌I. Construction Process Flow‌

1. ‌Preparation‌

   • Material transport and layout marking
   • Subbase profiling and survey control

2. ‌Subgrade Treatment‌

   • Leveling and compaction achieving:
     • ≤15mm surface regularity (4 checks per 200m)
     • ≥95% Proctor density
   • Removal of sharp protrusions (>20mm rocks)

3. ‌Geogrid Installation‌

   • Orientation perpendicular to traffic direction
   • Continuous deployment without twisting/wrinkling
   • Overlap specifications:
     • Longitudinal: ≥150mm
     • Transverse: ≥300mm

4. ‌Backfilling Procedure‌

   • Layered placement: sides → center
   • Max. drop height: 1.0m
   • Aggregate size: ≤15cm

5. ‌Fold-Back Treatment‌

   • 2.0m end section folding
   • Immediate coverage with fill material

6. ‌Lower Layer Construction‌

   • Sequential installation protocol

‌II. Installation Methodology‌

‌A. Subgrade Preparation‌

• Grading to ≤0.5% cross-slope
• Moisture conditioning (optimum ±2%)

‌B. Geogrid Deployment‌

1. Avoid UV exposure >48 hours
2. Pre-tensioning at 1.2–1.5% strain
3. Anchoring with galvanized U-pins (1m grid)

‌C. Fill Placement‌

• Symmetrical spreading from edges inward
• Prohibited direct dumping on geogrid

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III. Specialized Installation Techniques‌

‌IV. Quality Control Metrics‌

‌Mechanical Compliance Standards‌

• Tensile strength: ≥40 kN/m
• Peel resistance: ≥1.5 kN/m
• Elongation at break: ≤10%

Note: Construction equipment >25t gross weight prohibited on exposed geogrids.