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PRESENTATION

FLOWABLE FILL

Presented By:

Mac McArthur, P.E.Construction Engineering Services Bureau

Mike LynchMaterials Bureau

Highways and Engineering Conference – February/March 2006

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AGENDA

WHAT IS FLOWABLE FILL?

WHY USE FLOWABLE FILL?

WHEN SHOULD FLOWABLE FILL BE USED?

HOW IS FLOWABLE FILL USED?

QUESTIONS/ANSWERS

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WHAT IS FLOWABLE FILL? OTHER NAMES

Controlled Low-Strength Material (CLSM) Controlled Density Fill Flowable Mortar Low Strength Slurry Cement Backfill Lean Mix Backfill Lean Fill Un-shrinkable Fill Flowable Fly Ash Flowable Backfill Flowable Grout

WHAT IT IS NOT! Non-Shrink Concrete (Old MDT Concrete Type – “NS”)

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NOT FLOWABLE FILL!Just Very Wet Concrete!

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SLUMP TEST?

THE WAY IT IS SUPPOSE TO LOOK

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WHY USE FLOWABLE FILL?• FLOWS LIKE A LIQUID• SETS LIKE A SOLID• SELF-LEVELING• REQUIRES NO COMPACTION• REQUIRES NO VIBRATION• TAKES THE PLACE OF CONCRETE• TAKES THE PLACE OF COMPACTED SOILS• TAKES THE PLACE OF COMPACTED SAND• FILLS VOIDS• IS REMOVABLE

Excavatable – Easily Removed with a Shovel Non-Excavatable – Easily Removed with Light Equipment (Backhoe or Bob Cat)

• COST EFFECTIVE

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14 REASONS TO USE FLOWABLE FILL1) Readily Available

2) Easy to Deliver

3) Easy to Place

4) Versatile

5) Strong and Durable

6) Can be Excavated to Remove

7) Requires Less Inspection

8) Allows Fast Return to Traffic

9) Will Not Settle

10) Reduces Excavating

11) Improves Worker Safety

12) Allow All-Weather Work

13) Reduces Equipment Needs

14) Requires No Storage

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STANDARD SPECIFICATIONS

551.03.1 Classification. I. Flowable Fill. Use flowable fill for bedding, encasement, and general backfill for trenches.

Flowable fill is also known as controlled low-strength material, controlled density fill, flowable mortar, and slurry cement backfill.

551.03.2 Composition of Concrete. E. Flowable Fill. Flowable fill is a mixture of portland cement, fly ash, fine aggregate, air entraining

admixture and water. Flowable fill contains a low cementitious content for reduced strength development. Submit a mix design for approval. No compressive strength testing is required for the mix design.

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Table 551-1 has the suggested mix guides for excavatable and non-excavatable flowable fill:

TABLE 551-1

FLOWABLE FILL MIX DESIGN GUIDE

MATERIALS EXCAVATABLE NON-EXCAVATABLE Cement, Type I or II 75.6-102.6 lb/yd³ (45-60

kg/m3) 75.6-151.2 lb/yd³ (45-90 kg/m3)

Fly Ash None 151.2-596.7 lb/yd³ (90-355 kg/m3)

Water

Mix designs must produce a consistency that will result in a flowable, self-leveling product at time of placement.

Mix designs must produce a consistency that will result in a flowable, self-leveling product at time of placement.

Air 5-35% 5-15% 28-Day Compressive Strength

Maximum 100 psi (690 kPa) Minimum 125 psi (860 kPa)

Unit Weight (Wet) 2,430-2,970 lb/yd³ (1,440–1,760 kg/m3)

2,700-3,375 lb/yd³ (1,600–2,000 kg/m3)

Furnish fine aggregate meeting Subsection 701.01.1 requirements. The fine aggregate has no

fineness modulus requirement. High air generators or foaming agents may be used in lieu of conventional air entraining

admixtures and may be added at the jobsite and mixed in accordance with the manufacturer’s recommendation.

The requirements for percent air, compressive strength and unit weight are for laboratory designs only and are not intended for jobsite acceptance requirements. Proportion fine aggregate to yield 1 cubic yard (1 cubic meter).

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551.03.5 Placing Concrete.

Place Flowable Fill meeting the following requirements:

1. Place by chute or pumping and use a tremie when placing through water. 2. Place to the designated fill line without vibration or other compaction methods. 3. Do not place when the ambient temperature is below 35o F (1.7o C). Protect from freezing for a

minimum of 36 hours after placement. 4. Use straps, soil anchors or other approved means of restraint when flowable fill is used for pipe

backfill and other uses that may result in flotation, uplift or misalignment; and 5. Confine the flowable fill material within the designated placement area. Prevent intrusion

damage to adjacent work areas and facilities from lateral hydraulic pressure of the fill during placement and prior to hardening. After placement leave the flowable fill undisturbed until the material has set.

551.03.7 Testing and Acceptance of Concrete. A. Compressive Strength Testing. (Text of parts #1 #2 and #3 not shown)

1. General. 2. Prestressed Concrete Members. 3. Class "SD" Concrete. 4. Flowable Fill. The Project Manager will determine when flowable fill may be covered based

on the following: a. Supports the weight of a person weighing at least 155 lbs (70 kg) without deforming the surface, when placed beyond the traveled way; or b. After 24 hours or obtains 35 psi (240 kPa) penetration resistance as measured by a pocket penetrometer, when placed within the traveled way. c. Do not use flowable fill as a driving surface. Grade surface of flowable fill within the traveled way to allow for specified depth and type of surfacing material.

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WHEN SHOULD IT BE USED?

PIPES/UTILITY CONDUITS Haunch/Sides For Large Pipe Backfill Small Culverts Backfill Conduits/Pull Boxes – Urban Traffic Projects

FILL ABANDONED FACILITIES Wells Sewer Lines and Manholes Small Culverts Underground Storage Tanks

RETAINING WALL BACKFILL

BRIDGE END BACKFILL Bridge Bureau Design and Approval

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CULVERT BACKFILL

PTW TRENCH BACKFILL

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RETAINING WALL BACKFILL

UTILITY CONDUIT BACKFILL

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HOW IS IT USED?

CONSTRUCTION METHODS Use Chute or Pump Do Not vibrate or Compact Cannot Freeze Provide Restraints to Prevent Flotation Confine Flow and Prevent Intrusion * Do Not Use as Driving Surface

TESTING Mix Design Required No compressive Strength Test Required Set Time (Weight of a Person or Penetrometer)

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TEST TRENCH

LESS THAN 24 HOURS

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HOW IS IT USED?(Continued)

FLOWABLE FILL HELP GUIDE

Link = http://mdtinfo.mdt.state.mt.us/const/manuals.shtml

OTHER USES FOR FLOWABLE FILL Short Span Bridge Rehabilitation * Large Culvert Rehabilitation *

PHOTOGRAPHS FOLLOW

17LOTS OF FLOWABLE FILL – NOTE CONFINEMENT

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QUESTIONS/ANSWERS