Subgrade Improvement
Rigidity is Important!
Researchers at the U.S. Army Corps of Engineers have under-
taken full scale testing of various geogrid products and
concluded that stiff geogrids outperform more flexible products.
terrafix ® Biaxial Geogrids are rigid, high tensile structures that
offer superior granular interaction compared with other geogrids.
terrafix ® Biaxial Geogrids are produced from an extruded sheet
of polypropylene which is then punched and drawn resulting in high
junction strength and stiffness.
Vertical Pressure
without Geogrid
Soft subgrade soils can create a short term and a long term
problem. If a permanent road is built over a soft soil without
proper treatment of the subgrade, the road will face on-going
performance issues. Likewise, even a temporary access road
can incur unnecessary costs if it is not built properly.
Stiffening the aggregate base through the mechanism of
interlocking will create a platform with enhanced load
distribution.
The same way that a snowshoe distributes a person’s
weight evenly over a large area, terrafix ® Biaxial
Geogrids reduce the stress applied to the subgrade.
Vertical Pressure
with Geogrid
Design Using the Giroud-Han Method
Dr. J.P. Giroud and Dr. Jie Han have researched and published the
most recent and innovative advancement in geosynthetic reinforced
road design in the last 20 years. Their report can be found in the
August 2004 edition of the ASCE Journal of Geotechnical and
Geoenvironmental Engineering. See chart on Page 4.
Using this method, road designers can account for:
- variable base course strength
- better performance from stiff, dimensionally stable geogrids
- number of load cycles and desired performance
- variable performance based on geosynthetic used
The resulting output is a reliable determination of the total
required aggregate thickness for unpaved and “pre-paved” roads
and working platforms. It is possible to realize aggregate
reductions of up to 60%.