What types of fill can I use with cellular confinement?
Depending on the application, fill options for cellular confinement includes: sand or granular fill; top soil with vegetation; aggregate; and concrete.
Do I need a geotextile separator under cellular confinement?
The use of a geotextile separator under cellular confinement depends on the application, the type of fill used in relation to the existing subgrade, as well as other factors. For park-on, drive-on applications, often a geotextile is required to provide the critical function of separation. For slopes, a geotextile may create a slip plane for the cell. Please consult a geotechnical engineer for guidance.
What is a J-Hook?
A J- Hook is basically #3 rebar bent like a candy cane.
How long do J-Hooks need to be?
The length of the J-Hook should be 3 times the Envirogrid® cell depth.
Which product and cell depth are appropriate for a channels?
It depends on the infill material. For most channels utilizing rock, the EGA30 product is used due to its larger cell aperture. The cell depth depends on how much rock is required. The rock should be an angular rock with a size no larger than 1/3 the depth of the cell.
Which product and cell depth are appropriate for park-on drive on applications?
This depends on the vehicle tire footprint. For passenger vehicles, the EG20 is typically appropriate. For larger vehicles, the EG30 is typically appropriate. If you are not sure of vehicle size, default to the EGA20. This information is offered with the understanding that it does not constitute a specific engineering design.
What would be the steepest slope you would recommend for the embankment sides while using your product?
The maximum steepness of the slope depends on the infill material. The infill materials’ specific angle of repose will determine at what steepness the infill will fall out of the cell. The project engineer will need to make this determination.
What product would you suggest for light duty road construction?
For light duty road construction we would suggest the 4" EGA20 material. Always verify product suitability with an engineer that is familiar with the project conditions.
What product would you suggest for heavy duty road construction?
For heavy duty roads (those experiencing maximum load weighted 18 wheelers) we would suggest the 6" or 8" EGA30 material. If the infill material is different than the subgrade, we would suggest adding a 6 oz. nonwoven geotextile (US 160NW) under the cell. This information is not offered as an engineered design.
Can Envirogrid™ be used under track with railroad ballast?
Railroad ballast is an excellent application for Envirogrid™. The function of ballast in a railroad application is the same as the function of crushed rock in an unpaved road: to spread the loads imposed upon it by traffic from above to the layer below. If an Envirogrid™ panel with a small cell area is used with well-compacted ballast, the Envirogrid™/ballast system would distribute loads effectively as long as that compaction is maintained.
Internal friction is the mechanism that allows the ballast to spread the load and reduce the pressure on the subgrade. As the ballast is fouled with soil fines over the life of the track, the ballast layer must be cleaned or replaced. Fouling diminishes the internal friction, or the piece-to-piece (individual rock to individual rock) friction. However, the Envirogrid™ will confine the full depth of the ballast, maintaining a large percentage of its load distribution property even after some fouling takes place.
If the ballast layer is exposed directly to the subgrade soil, the Envirogrid will not prevent soil particles from being forced up into the ballast section. So a key question for the engineer is whether or not to use a separation fabric to prevent migration of fines and pumping. The separation geotextile should be a heavy weight non-woven. However, introduction of a nonwoven fabric on a steep grade, even if it has a relatively high coefficient of friction with respect to the subgrade, would increase the sliding potential of the fabric/Envirogrid™/ballast system. Therefore, you would need to anchor the track to the subgrade.
This information is offered with the understanding that it does not constitute an engineering opinion for a specific project.
Can an Envirogrid™ gravity wall be placed in front of an existing wall?
Envirogrid gravity walls can be built in front of existing walls. If the cellular confinement wall comes into intimate contact with the existing wall, it creates a composite wall system with greater sliding and overturning resistance and is better suited to resist loading. This information is offered as a guideline and does not constitute a project specific design.
Is exposure to the environment an issue for Envirogrid™?
Envirogrid is made of HDPE, the same material from which landfill liners are made, so exposure to the elements is typically not of great concern.
What is the coefficient of friction for Envirogrid™?
The polyethylene strips are textured and perforated such that the peak friction angle between the surface of the textured/perforated plastic and a #40 silica sand at 100% relative density is no less than 85% of the peak friction angle of the silica sand in isolation when tested by the direct shear method per ASTM D 5321.
Do you have any cellular confinement installation videos?
Yes. Click on this link to watch a YouTube video showing Envirogrid™ installed on a slope. This video shows stapling of panels; drilling holes for tendons; and tendon installation: Envirogrid™ Installation