FLOWABLE FILL

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FLOWABLE FILL

• The Controllable Backfill

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WHAT IS FLOWABLE FILL?

• DEFINITION - Flowable Fill is a self compacting,
  cementitious material used primarily as a
  backfill material in lieu of compacted-soil
  backfill.
• Defined in ACI 229R-94.

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Other Terms for Flowable Fill

• CLSM - Controlled Low Strength Material
• CDF - Controlled Density Fill
• Flowable compacting fill
• Lean fill
• Ready mixed flowable fill
• Flow fill

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What Is a Flowable Fill Mix?

• Main Ingredients
• Cement
• Sand
• Water
• with
• Fly Ash
• GGBF Slag
• Stable Air Generators

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Properties of Flowable Fill

• High Slump
• (9 /-)
• Low Strength
• Commonly 100 PSI (0.7 Mpa) in 28 days

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Flowable Fill is NOT Concrete

• Similarity ends with delivery vehicle
• Low cementitious
• Does not hydrate
• Settles, dewaters
• The wetter the better
• Less water does not equate to faster hardening
• Too little water will not allow proper settlement

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Therefore . . .

• Specification offers
• Flexibility of design
• Minimal mix design testing
• Little or no field testing required

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Typical Flowable Fill Mixes

• Standard Type
• Portland Cement 35
• Fly Ash 300 400
• Sand 2600 (/-)
• Water 415 460
• Air 6
• optional

• Air Generated
• Portland Cement 80
• Sand 2400
• Water 295
• Air (design) 30

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PennDOT Specification Section 220
Bottom Ash or Coarse Agg or Fine Agg or Air
Generating Admixture
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Compacted-Soil Backfill Concerns

• LACK OF COMPACTION -- Causes most call-backs to
  repair settlement problems.
• Improper backfill is the number one complaint of
  public works directors.
• How to Get Utilities to Repair Streets Right,
  Better Roads, April,
  1990
• Study indicates that 65 of utility cut
  restorations were unsatisfactory.
• Utility Cut Restoration, Metropolitan Toronto
  Roads And Traffic Department, April 1985

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Other Concerns

• Compaction around pipes for support.
• Number of compaction lifts
• Increases project construction time.
• Continuous testing.
• Requires continuous inspection.
• Safety of workers.
• Moisture content.
• Storage of materials on site.
• Inconsistent soil test results.

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Benefits of Flowable Fill

• Reduced in-place costs
• less labor equipment
• Minimized settlement
• Easily removable
• Durable
• Versatile

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Benefits of Flowable Fill

• Year-round availability
• No compaction required
• Self leveling
• Increased worker safety
• Can Be color-coded for utility identification

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Single-pass filling of voids speeds project
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Flowable Fill Saves Money

• Labor Costs for Placing Granular Backfill
• Placement 73.98
• (2 laborers _at_ 36.99/hr)
• Compaction 73.98
• (2 laborers _at_ 36.99/hr)
• Heavy Equip. Operator 40.33
• Hand Compactor 15.00
• Backhoe 25.00
• Total labor for granular fill 228.30

National Industry Average incl. overhead costs
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Flowable Fill Saves Money

• Labor Costs for Placing Flowable Fill
• Placement
  36.99
• Compaction
  n/a
• Heavy Equipment _n/a_
• Total labor for Flowable Fill 36.99
• Total labor for Granular Fill 228.30
• Labor savings
  181.31

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Flowable Fill Applications

• Backfill
• Structural Fill
• Other Uses

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Flowable Fill as Backfill

• Where speed of construction is advantageous and
  where better performance is required.
• Ideal for use in tight or restricted areas where
  placing soil fill is difficult.
• Trenches utilities, primarily under
  roadways
• Bridge abutments
• Pipe bedding
• Building excavations
• Wet conditions

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Flowable Fill as Structural Fill

• Road base
• Mud jacking
• Sub footing
• Floor slab base

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Other Uses for Flowable Fill

• Abandoned sewers, tanks, pipe, etc.
• Environmental remediation
• Slope stabilization

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Typical Areas Which are Difficult to Compact
Underground Tanks Foundation Wall
Backfilling

• Road Cuts
• Under Around Pipes

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Fast Track Fill and Pave

• Backfill trench with CLSM to 4 below street
  level.
• Place a concrete overlay of 4000 PSI (28 Mpa)
  concrete pavement.

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CLSM IS EXCAVATABLE WITH CONVENTIONAL EQUIPMENT

• 100 PSI CLSM can be excavated with backhoe
• Can also be dug with pick and shovel

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Where Can I Get Flowable Fill?

• From Your Local Ready Mix Producer

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IN CONCLUSION

• For better quality construction,
• consider using
• FLOWABLE FILL
• on your next project.

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For Further Information

• Contact
• Pennsylvania Concrete Promotion
  Council 800-251-0616
• www.paconcrete.com