Case Studies - Geogrid

geogrids: base stabilization, reinforcement, sepAration, and filtration

case study

Geogrids help facilitate efficient stabilization of poor soils for construction projects. Geogrids are specified for a variety of reasons such as designing an embankment over a weak subgrade, a working platform over expansive clays, or a foundation requiring extra reinforcement. In base reinforcement applications such as paved or unpaved roads, geogrids are used to provide reinforcement and confinement to base course materials. Geogrid soft soil stabilization techniques provide solutions to conventional techniques such as deep undercutting and chemical stabilization by reducing construction time, costs, and difficulties.

PROBlEM:

An industrial road leading to manufacturing facilities and a quarry with heavy duty vehicles and heavy truck traffic. The road was narrow and built on soft soils with shallow overgrown ditches. A high water table and standing water in the adjoining ditches added to the problem. Furthermore, the project timetable was moved up by the owner with a winter completion deadline.

SOLUTION:

A full rigid asphalt pavement design was completed for this project with for a 20 year life and a future ADT (average daily traffic) at 3400 vehicles/day at 100% trucks. A full depth asphalt pavement design of 14.5” bituminous (13” binder under a 1.5” surface mix) over a 12” improved sub grade consisting of 9” of 4”minus stone, a layer of base reinforcing geogrid, and 3” of CA-6” minus cap. This will stabilize the base, lower the water table, and improve the drainage of the roadway.

PRODUCT:

ERO-TEX MS330 MULTILAYER GEOGRID. Multilayer geogrids are composed of several layers of high strength extruded biaxial oriented polypropylene polymers. The layers are rolled and stitched together without superimposing the grids creating random sized apertures designed to accommodate a wide range of fill materials and soils. This product was chosen due to the excellent drainage properties, superior interaction with the sub grade soils, and its high tensile properties.

Typically the fill material used in base reinforcement is a quality granular material with specific structural characteristics. This high quality granular fill can also be very expensive. By incorporating bi-directional base geogrids, the required thickness can be significantly reduced translating into significant cost savings.