Installation Guidelines
Site Preparation
- Standard excavating, grading and compaction equipment should be used to grade and compact the area to be protected and to excavate anchor, flank and toe trenches.
- Vegetation and obstructions, such as roots and projecting stones, should be removed.
- Unsuitable soils should be removed and replaced with select material and compacted according to contract specifications.
- Draglines and bulldozers are suitable for rough grading, but fine grading shall be performed with backhoe, grader or similar equipment.
- Underwater installation may be facilitated if a leveling course of granular material is placed prior to fabric form.
Panel Placement
Establish Starting Point & Alignment Lines
- It is custom to work from upstream
to downstream
- Prevents construction flows from
undermining or bunching fabric
- String lines are set both parallel
and perpendicular to slope in an offset manor
Placement of first fabric panel
- Panels are identified for
placement according to fabrication drawings
- Panels are accordion folded and
then rolled
- Panels should be extended into
position by pulling the leading side of panel
- Panels should be placed loosely
and extra form contraction should be gathered into temporary tucks at each
seam and at top of slope
Placement of remaining fabric panels
- If panels are sewn together in the
field, the succeeding panel is place atop the last mil width.
- Panels are then joined together
edge-to-edge, by sewing the top layers and bottom layers independently
- If panels are joined together with
pre-installed zippers, the succeeding panel is placed adjacent to last mil
width
Fine Aggregate Pumping
- Fine aggregate concrete is pumped into the forms by inserting a 2ӯ grout hose through a small slit in the top layer of fabric
- In order to control the position and prevent sliding, concrete is either pumped into the portion of the panel that has been placed into the anchor trench or is secured with sand bags
- A tight seal is made by wrapping nonwoven fabric around the pipe, as well as closing the slit once pumping has discontinued
- First section of panel is left un-pumped to prevent fabric from sliding into flank trench
- Starting in the second section, the injection pipe should be inserted inside the first baffle and at a distance from the toe as determined by slope angle and fabric type
- The flow of concrete should always be directed toward toe of slope
- Spacing of injection ports is also determine by slope angle and fabric type
- As the fabric is being pumped the panel will contract causing a tightening of the form
- As one baffled section is fully inflated, contractor will repeat theses steps along the alignment of the plans until entire lining has been pumped
- Each individual baffle sewn into the fabric form will act as a cold joint, allowing contractor to control the work flow
- Once concrete has cured (approximately 24 hours), toe and flank trenches can be backfilled and compacted
Mix-Design
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TYPICAL RANGE OF MIX
PROPORTIONS
|
||
|
Material |
Mix Proportions |
After Placement lbs./cu. yd. |
|
Cement |
750-850 |
810-920 |
|
Sand |
2030-2120 |
2195-2290 |
|
Water |
485-555 |
|
|
Fly Ash |
Up to 25% of Cement |
|
Fabric formed fine aggregate concrete possesses superior physical properties. The compressive strength of fine aggregate concrete pumped into fabric forms is typically 1.5 to 1.75 times greater than companion samples taken from conventional concrete testcylinders. In addition, the fine aggregate concrete has less than 5% water absorption. This combined with a "case hardening" effect produces a concrete thatis abrasion resistant durable under freeze thaw action resistant to "breakup caused by thermal cracking, highly impermeable, and resistant to acid, alkali salt, organic solvents, biological organismsand petrochemicals and permits FFC revetments to be constructed without reinforcement steel
Installation Tips
- Always maintain appropriate slack throughout fabric to prevent fabric stretching, pinching, over-stressing and non-uniform thicknesses
- Average pumping speed is 15 yd3/hour
- Standard pumping distance from worksite is 500 linear feet, with as much as 2,500 linear feet possible with sufficient pump(s) set-up
- Concrete line pumps are the choice pump for ease of installation. They are portable, towable, small and can pump various mix designs. Boom trucks are NOT recommended
- Proper mix design is critical to a smooth, efficient, and successful installation
- Pumping procedures and sequence is key to preventing installation malfunctions
- Typical crew size includes 4 laborers, 1 pump operator, and 1 superintendent