Plastic Biaxial Geogrid Tips: How to Choose Backfill Material

2026-03-16

The backfill material used for geogrids must have several characteristics：

High tensile modulus and low elongation (match the characteristics of geogrids)
Good engineering properties;
Effective "interlocking" and "frictional force" transmission.

The following are recommended backfill materials：

1. Coarse-grained soil (preferred)

Type: Well-graded gravel, crushed stone and sand-gravel mixtures.

High strength interlocking	The angular coarse particles can generate strong mechanical interlocking with the geogrid's openings and ribs
High internal friction angle	High inherent strength and large friction force with the geogrid.
Good permeability	Less water accumulation, maintaining long-term stability.

Note: The maximum particle size should be less than one-third of the backfill layer thickness and no larger than the geogrid mesh size to prevent stress concentration and geogrid damage.

2. Sandy soil

Type: Well-graded medium to coarse sand, sand with a small amount of gravel.

Good friction	Sufficient friction resistance with the geogrid surface
Easy compaction	Good construction performance and convenience

Note: Pure fine sand has weaker friction angle and interlocking force, resulting in less effective performance compared to coarse-grained soil.

Application Scope: Railway, highway, common road with high load or middle load

3. Sticky soil

Sticky soil may have a high water content and is not easily compacted, with insufficient resistance to creep. If used, it needs to be mixed with sand, gravel or crushed stone, and proper drainage should be ensured if possible.

Application Scope: Soft soil subgrade with low load

4. Organic soil, humus soil and frozen heave soil (not recommend)

Low strength, high compressibility and trend to decay may lead to structural damage.

The backfill material for geogrids will directly affect the final performance indicators in the project, so it should be selected based on site conditions and actual situations to ensure both cost and safety requirements are met.