In April 1998, the Kentucky Department of Transportation (KDOT) began the Bryan
Station Road widening project in Lexington, Kentucky through an area of
expansive clays and alluvial topsoil. Due to the presence of these soils,
KDOT specified that a biaxial geogrid be placed between the existing
subgrade and the base aggregate. Through a competitive bidding and approval
process, Bluegrass Contracting Company, the general contractor installed
approximately 22,999 yd² of FORNIT® 30 biaxial geogrid on this project.
The highway design section above the existing subgrade consisted of the following:
- FORNIT® 30 biaxial geogrid
- 6 inches of 1½ inch minus base course aggregate
- 9½ inches of an asphalt base course
- 1¾ inches of asphalt wearing surface
The project was completed in November 1999.
Conclusions
Severe pumping and rutting was observed in the unreinforced test section, while only rutting attributed to aggregate compaction was observed at the FORNIT® 20 reinforced section.
Although the test section was limited to a small number of truck passes, FORNIT® 20 biaxial geogrid provided excellent tensile reinforcement, separation, and confinement to the aggregate base layer.
FORNIT® 20 biaxial geogrid distributed tensile forces induced by the dump truck over a larger area, thereby reducing soil bearing capacity requirements. Pullout tests performed by independent laboratory also substantiates this fact.
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