FLOWABLE FILLUSING

GLASS CULLET

PENNDOT’s Glass Cullet WorkshopDecember 2003

Strategic Environmental Management Program Office

Presented by: Jelena Vukov, PEApex Environmental, Inc.

Flowable Fill – Definition:

Flowable Fill is also known as:

Controlled Low-Strength MaterialUnshrinkable fillControlled Density FillFlowable mortarFlowable fly ash…

What is Flowable Fill?

FLOWABLE FILL.. is a self-compacted, cementitious material

used primarily as a backfill in lieu of compacted fill.

Components of Flowable Fill

Conventional Flowable Fill mixtures consist of:

- Water- Portland Cement- Fine or Coarse Aggregates (or both)- Fly ash - Other By-products (foundry sand, chemical

admixtures, accelerators, foaming agents)

Flowable Fill Materials

CementStrength and hardening times

50-200 lbs/yd3

Fly ashProvides flowabilityAggregate filler

Ranges: 0-2000 lbs/yd3 (as aggregate filler)

AggregateFine aggregateCoarse Aggregate

2600-3100 lbs/yd3

Typically 50% mix of total aggregates

WaterHigher content that in concrete mixes

325-580 lbs/yd3 (with aggregates)1000 lbs/yd3 with fly ash

When is it Flowable Fill Used?

Typically used in lieu of compacted fill in various applications, especially for:

- Backfill (retaining walls and trenches)- Utility Bedding (pipe, electrical and other

utility and conduits)- Void Fill (sewers, tunnel shafts,

basements, and other underground structures)

- Bridge approaches (subbase material)

Backfill – Flowable FillAdvantages of Using

Flowable Fill:- Easier accessibility

for equipment- Trench width can be

kept to a minimum- No need for leveling- No compaction

needed- Minimal, if non-

existent settlement

Other Advantages

• Readily available local materials• Easy to deliver and place• Self-leveling • Minimal to no settlement• Strong and durable• May reduce excavation cost (narrower trenches)• Can use by-products as replacement of

aggregate or cemetitious material fraction

Disadvantages or Challenges Using Flowable Fill:

• Less known and not widespread use• Higher material costs – lower equipment

and labor costs• Design strength must reflect future

excavation and removal needs• Often compared to concrete

Cost ComparisonsFlowable Fill vs. Conventional AggregateSource: Hennis and Frishette, 1990

Flowable Fill Units Required

Price/ Unit

Price

Backfill:

Flowable Fill (including supervisor and labor)

2.2 m $49.92 $109.82

Asphalt Fill:Fill Truck 2.2 m $50.18 $110.40

Total $100.10 $220.22

Cost ComparisonsFlowable Fill vs. Conventional Aggregate

Aggregate (conventional) Fill with Plate and Permanent Trench

Units Required

Price/ Unit

Price

Backfill:#57 Stone 3.93 metric

tons$7.20 $28.21

Haul Charge 2 hours $38.00 $76.00

Labor 1 hour $22.00 $22.00

Truck & Ground Pounder 1 hour $7.00 $7.00Supervisor 1 hour $24.20 $24.20

Steel Plates 2 $50.00 $100.00Asphalt Fill:

Fill Truck 2.2 m $50.18 $110.40

Total $167.19 $367.81

Source: Hennis and Frishette, 1999

Flowable Fill Cost Components

Concrete Material Costs:

Cement: $22/ m3

Fine Aggregate: $6/ m3

Coarse Aggregate: $8/m3

Flowable Fill Costs:

Cement - $4 / m3

Aggregate Filler: $10.5/m3

Fly Ash: $3/m3

Source: Brewer and Hurd, 1992

Pub. 408 Specifications

PENNDOT Pub. 408 – Section 220 –FLOWABLE BACKFILL

Available electronically on:www.dot.state.pa.us

Doing Business with PENNDOTConstruction Specification

Pub. 408 – Section 220-Flowable Backfill

220.1 DESCRIPTION—This work is furnishing, transporting, and placing backfill. Flowable backfill is a mixture of coarse aggregate, fine aggregate, water and air entraining agents, either cement or pozzolans, or a combination of both, and may or may not include bottom ash, or other admixtures. The four types of flowable backfill are as follows:

(a) Flowable Backfill, Type A and Type B. Future excavation of the backfill may be necessary such as at utility trenches, pipe trenches, bridge abutments, and around box or arch culverts.

(b) Flowable Backfill, Type C. Excavation of backfills not anticipated, including replacing unsuitable soils below structure foundations, filling abandoned conduits, tunnels and mines, and backfilling around pipe culverts where extra strength is required.

(c) Flowable Backfill, Type D. Construction in areas requiring low-density backfill material as in abutments over highly deformable soils, backfilling retaining walls, filling vaults and backfilling on top of buried structures.

Pub. 408 – Section 220-Flowable Backfill220.2 MATERIAL—(a) Cement. Type I, IP, or II, Section 701. When using Type IP cement, adjust the quantity of flyash in

the design as necessary. From a source listed in Bulletin 15.(b) Flyash. Type F or C flyash, Section 724 except as follows:

Flyash – in accordance with AASHTO M295 (or ASTM C618) Table 1 requirements except maximum loss on ignition is 16% and excluding the requirements of Table 1A, 2, or 2A. From a source listed in Bulletin 15 or tested and approved prior to incorporation into flowable backfill mix.

(c) Ground Granulated Blast Furnace Slag. Section 724.3. From a source listed in Bulletin 15.(d) Fine Aggregate. Type A, B, or C; Section 703.1; except, having a maximum loss of 20% in the

Soundness Test, PTM No. 510. The fine aggregate may be natural sand, manufactured sand or foundry sand meeting Section 703.1. From a source listed in Bulletin 14.

(e) Coarse Aggregate. Type A, B, or C, AASHTO No. 10, Section 703.2. Except 10% maximum for the material finer than the 75 µm (No. 200) sieve. From a source listed in Bulletin 14.

(f) Bottom Ash. From a source listed in Bulletin 14. Coal ash having a maximum loss of 20% in the Soundness Test, PTM No. 510, and meeting the following dry sieve gradation requirements: Sieve Size (PTM No. 117) - 100% Passing 12.5 mm (1/2-inch) ; and 0-10 % passing 75 µm (No. 200) .

(g) Water. Section 720.1(h) Admixtures. Section 711.3. Including air generating admixtures.(i) Geotextile, Class 4, Type A. Section 735(j) Mix Design. Submit a mix design and test results (density and strength) to the Representative, at

least three (3) weeks before construction. Use Table A as a guideline for the mix design or submit an alternate design based on density guidelines and meeting the strength requirements of Table A. Base the submitted mix design on an absolute volume of 1 m3 (1 cubic yard).

TABLE AMix Design

Properties & Criteria Type A Type B Type C Type D

Mix Design (/m3(/CY)Cement (kg/(lbs))*Pozzolans (kg/(lbs))*Bottom ash (kg/(lbs))*Or Coarse AggregateOr Fine AggregateAir Generating Admixture

45 (100)910 (2000)

0

23 (50)136 (300)

1180 (2600)

68-90 (150-200)136 (300)

1180 (2600)

136-320 (300-700)45-180 (100-400)

**

Slump (mm (inches))AASHTO T 121, C 136

178 (7) min****

178 (7) min****

178 (7) min****

178 (7) min****

Density (kg/m3 (pcf))AASHTO T121, C 136

N/A N/A N/A 480-1120 (30-70) Or as specified

Water Absorption ofAggregate AASHTO T 85

-- -- -- --

Comprehensive Strength(Mpa (psi))PTM No. 604 28 Days

0.86(125) max

0.86 (125) max

5.51 (800) min 0.62-2.75 (90-400)

Pennsylvania State University &Pennsylvania Transportation Institute

Study

Integration of Recycled and Co-product Materials in Controlled Low-Strength Material, December 1999

Purpose: To provide recommendations to PENNDOT on the use of recycled or co-product materials in flowable fill.

Pennsylvania State University &Pennsylvania Transportation Institute

Study

Materials tested:

Fly ashSpent Foundry SandGlass Cullet (Fine and Coarse)Reclaimed Portland Cement Concrete

Pennsylvania State University &Pennsylvania Transportation Institute Study

Conclusions and Recommendations:

All secondary materials were deemed acceptable for the use in flowable fill

Excluding: …. Coarse (Unprocessed) Glass Cullet

PENNDOT CLSM mixture designs – using Glass Cullet (Fine)

Component (kg/m3) Type ASection 220-

Table A

Type BSection 220-

Table ACement 60 30

Water (L/m) 264 277

Fly Ash 305 170

Glass Cullet (Fine) 915 1,500

* For Unprocessed Glass Source: PENNDOT, 1995.

Glass Cullet Study Parameters

Fine glass cullet used (Source: D.M. Stoltzfus & Sons) :

Gradation: Absorption: 1.3%Specific Gravity: 2.29Debris Level: 0%

Used in Type A & Type BFlowable Fill Design Mixes

Source: Dec. 1999, Final Report

Sieve Size Percent Passing

3/8 inch (9.5 mm)No. 4 (4.75 mm)No. 8 (2.36 mm)No. 16 (1.18 mm)No. 30 (600um)No. 50 (300 um)No. 100 (150 um)

100100805030155

Design Mix Results

Type A – Glass Cullet Mix

No SegregationW/C = 4.4Bleeding = 0Plastic Density (1,950 kg/m3)Initial Set (hr) = 5.17 hrCompressive Strength

= 1.02 Mpa (28-day)

Type B – Glass Cullet Mix

No SegregationW/C = 9.2Bleeding = 102 ml (3-hr)Plastic Density (1,920 kg/m3)Initial Set (hr) = 4.92 hrCompressive Strength

= 0.46 Mpa (28-day)

Study ConclusionsGeneral Conclusions:• All mixtures reached compressive strengths that

correspond to excavatable material• Flowable fill mixtures are extremely sensitive to amount of

water added;• Bleed water ceases to accumulate between 2.5 and 3.5

hours• Density decreases with increased water content and with

aggregates of low specific gravity• Hardening time is decreased with increasing cement

content• Compressive strength sensitive to cement content and use

of coarse aggregates

Study Conclusions – specific to glass cullet mixes:

Specific Glass Cullet Conclusions:• Fine glass cullet performed satisfactorily, with

compressive strengths and hardening times higher than of the control mixtures

• Coarse Unprocessed Glass Cullet did not meet performance requirements

• Recommended maximum debris level for glass cullet material: <2%

PENNDOT DemonstrationField Demonstration Project, May 2000, District 6-0,

Flowable Fill for pipe backfill using recycled materials– May 2000

• Demonstration Criteria: needs to be excavatable for trench backfill• Recycled materials used: foundry sand, blast furnace slag, glass

cullet• Demonstration logistics:

Unauthorized changed in design mix (ground granulated blast furnace slag was substituted for fly ash)Produced structural backfill vs. excavatable backfillSuitable for sinkholes, voids, bridge abutments, but not for pipe trench backfill.Easy placement, self-compacted, final set reached in 8 hours, could support light traffic in 24 hours.Glass cullet did not influence the compressive strength.

Question:Did PENNDOT specifically allow for the use

of glass in Flowable Fill- Section 220 specification?

Answer:No, glass is not specifically listed in the

Materials Section. 220

Pub. 408 – Section 220-Flowable Backfill

220.1 DESCRIPTION—This work is furnishing, transporting, and placing backfill. Flowable backfill is a mixture of coarse aggregate, fine aggregate, water and air entraining agents, either cement or pozzolans, or a combination of both, and may or may not include bottom ash, or other admixtures. The four types of flowable backfill are as follows:

(a) Flowable Backfill, Type A and Type B. Future excavation of the backfill may be necessary such as at utility trenches, pipe trenches, bridge abutments, and around box or arch culverts.

(b) Flowable Backfill, Type C. Excavation of backfills not anticipated, including replacing unsuitable soils below structure foundations, filling abandoned conduits, tunnels and mines, and backfilling around pipe culverts where extra strength is required.

(c) Flowable Backfill, Type D. Construction in areas requiring low-density backfill material as in abutments over highly deformable soils, backfilling retaining walls, filling vaults and backfilling on top of buried structures.

Pub. 408 – Section 220-Flowable Backfill220.2 MATERIAL—(a) Cement. Type I, IP, or II, Section 701. When using Type IP cement, adjust the quantity of flyash in

the design as necessary. From a source listed in Bulletin 15.(b) Flyash. Type F or C flyash, Section 724 except as follows:

Flyash – in accordance with AASHTO M295 (or ASTM C618) Table 1 requirements except maximum loss on ignition is 16% and excluding the requirements of Table 1A, 2, or 2A. From a source listed in Bulletin 15 or tested and approved prior to incorporation into flowable backfill mix.

(c) Ground Granulated Blast Furnace Slag. Section 724.3. From a source listed in Bulletin 15.(d) Fine Aggregate. Type A, B, or C; Section 703.1; except, having a maximum loss of 20% in the

Soundness Test, PTM No. 510. The fine aggregate may be natural sand, manufactured sand or foundry sand meeting Section 703.1. From a source listed in Bulletin 14.

(e) Coarse Aggregate. Type A, B, or C, AASHTO No. 10, Section 703.2. Except 10% maximum for the material finer than the 75 µm (No. 200) sieve. From a source listed in Bulletin 14.

(f) Bottom Ash. From a source listed in Bulletin 14. Coal ash having a maximum loss of 20% in the Soundness Test, PTM No. 510, and meeting the following dry sieve gradation requirements: Sieve Size (PTM No. 117) - 100% Passing 12.5 mm (1/2-inch) ; and 0-10 % passing 75 µm (No. 200) .

(g) Water. Section 720.1(h) Admixtures. Section 711.3. Including air generating admixtures.(i) Geotextile, Class 4, Type A. Section 735(j) Mix Design. Submit a mix design and test results (density and strength) to the Engineer, at least

three (3) weeks prior to construction. Use Table A as a guideline for the mix design or submit an alternate design based on density guidelines and meeting the strength requirements of Table A. The submitted mix design must be based on an absolute volume of 1 m3 (27 cubic feet).

Pub. 408 – Section 220 Materials

(d) Fine Aggregate. Type A, B, or C; Section 703.1; except, having a maximum loss of 20% in the Soundness Test, PTM No. 510. The fine aggregate may be natural sand, manufactured sand or foundry sand meeting Section 703.1. From a source listed in Bulletin 14.

(e) Coarse Aggregate. Type A, B, or C, AASHTO No. 10, Section 703.2. Except 10% maximum for the material finer than the 75 µm (No. 200) sieve. From a source listed in Bulletin 14.

Section 703.1 - TABLE A FINE AGGREGATE - Grading and Quality Requirements

Cement Concrete

Sand

Bituminous Concrete SandType B

Mortar Sand

Glass Cullet (aver.)

Sieve Size Type A #1 #2 #3 Filler Type C9.5 mm (3/8-in) 100 100 - 100 - -

4.75 mm (No. 4) 95-100 95-100 100 80-100 - 1002.36 mm (No. 8) 70-100 70-100 95-100 65-100 - 95-1001.18 mm (No. 16) 45-85 40-80 85-100 40-80 - -

600 µm (No. 30) 25-65 20-65 65-90 20-65 100 -

300 µm (No.50) 10-30 7-40 30-60 7-40 95-100 -

150 µm (No.100) 0-10 2-20 5-25 2-20 90-100 0-25

75 µm (No.200) - 0-10 0-5 0-10 70-100 0-10

<75 µm (No.200) 3 - - - - - Ave. 2.0

Strength Ratio Min. Percent

95 - - - - 95

Soundness Test Max. Loss %

10 15 15 15 - 10 6.3-7.1

Fineness Modulus

2.3-3.15 - - - - 1.6-2.5

Section 703.2 - TABLE B COARSE AGGREGATE - Quality Requirements

Type A Type B Type C Glass Cullet

Soundness, Max. % 10 12 20 6.38-7.1Abrasion, Max. % 45 45 55 24-25Thin and Elongated Pieces, Max. % 15 20 -

Material <75 µm (No. 200), Max. % * * 10 1.2-3.2

Crushed Fragments, Min. % 55** 55** 50 N/ACompacted Density (Unit Weight), Min. kg/m3

(lbs./cu.ft.)1100 (70) 1100 (70) 1100

(70)(72-79)

Deleterious Shale, Max. % 2 2 10 N/AClay Lumps, Max. % 0.25 0.25 3 N/AFriable Particles, Max. % (excluding shale) 1.0 1.0 - N/A

Coal or Coke, Max. % 1 1 5 N/AGlassy Particles, Max. % 4 or 10*** 4 or 10*** - 100

Iron, Max. % 3***** 3***** 3***** N/AAbsorption, Max. % 3.0**** 3.5**** - 1.3Gradation – AASHTO #10Total Deleterious Shale, Clay, Lumps, Friable Particles, Coal, or Coke Allowed, Max. %

2 s 15 N/A

Conclusion:

Obstacles for using glass cullet in Flowable fill with current Pub. 408

Flowable Fill specifications:

• Bulletin 14 Requirement• Table A – Fine Aggregate• Table B – Coarse Aggregate

(except Type C)• Restriction to Glassy Particles (4 or 10%)

Can glass cullet still be used, …when recycled glass is specifically not

included in the Materials Section 220?

Answer:

Yes – Here is how and why.

Available specification mechanism

Pub. 408 – Section 220-Flowable Backfill220.2 MATERIAL—

(j) Mix Design. Submit a mix design and test results (density and strength) to the Engineer, at least three (3) weeks prior to construction. Use Table A as a guideline for the mix design or submit an alternate design based on density guidelines and meeting the strength requirements of Table A. The submitted mix design must be based on an absolute volume of 1 m3 (27 cubic feet).

NOTE:Section 220.2 (j) Mix Design is the ONLY current available mechanism to use glass. No Bulletin 14 or Bulletin 15 is specified !!

Available specification mechanism

Pub. 408 – Section 220-Flowable Backfill220.2 MATERIAL—

(j) Mix Design. Submit a mix design and test results (density and strength) to the Engineer, at least three (3) weeks prior to construction. Use Table A as a guideline for the mix design or submit an alternate design based on density guidelines and meeting the strength requirements of Table A. The submitted mix design must be based on an absolute volume of 1 m3 (27 cubic feet).

NOTE:Section 220.2 (j) Mix Design is the ONLY current available mechanism to use glass. No Bulletin 14 or Bulletin 15 is specified !!

TABLE AMix Design

Properties & Criteria Type A Type B Type C Type D

Mix Design (/m3(/CY)Cement (kg/(lbs))*Pozzolans (kg/(lbs))*Bottom ash (kg/(lbs))*Or Coarse AggregateOr Fine AggregateAir Generating Admixture

45 (100)910 (2000)

0

23 (50)136 (300)

1180 (2600)

68-90 (150-200)1180 (2600)

136-320 (300-700)45-180 (100-400)

**

Slump (mm (inches))AASHTO T 121, C 136

178 (7) min****

178 (7) min****

178 (7) min****

178 (7) min****

Density (kg/m3 (pcf))AASHTO T121, C 136

N/A N/A N/A N/A

Water Absorption ofAggregate AASHTO T 85

-- -- -- --

Comprehensive Strength(Mpa (psi))PTM No. 604 28 Days

0.86 (125) max

0.86 (125) max

5.51 (800) max 0.62-2.75 (90-400)

PENNDOT Project Specific Approval

Using Section 220.2 Material (j) Mix Design:

• Allows for PERFORMANCE based evaluation. Slump and strength requirements must be met.

• Flowable Fill mixes using glass cullet have met the performance criteria.

• Need approval from Material Testing Division.• Alternatively: Demonstrate that Glass meets Fine

Aggregate/Coarse Aggregate Criteria w/o meeting Bulletin 14, and w/o restricted by 4-10% Glassy Particle requirement.

New Project Underway

• District 5-0, State Route 222• Approved flowable fill with glass cullet as a

substitute for fine aggregate to be used for filling sink holes application on an as needed basis.

• Design mix approved by Materials Testing Division.

• SEM Program Office offered technical support letter.

• Contractor Initiated.

Conclusions

CURRENT STATUS:• Glass Cullet is appropriate for use in Flowable Fill

Applications• No specifications directly allow for its use• Use Design Performance Criteria and Project

Specific Approval• SEM Program Office will document results of SR

222 flowable fill applicationFUTURE OBJECTIVES:• ? Revisions to existing Pub. 408 specifications • ? PENNDOT Provisional Specifications

Contact Information

Kenneth J. Thornton, PGChief, Pollution Prevention SectionP.O. Box 400Harrisburg, PA 17105

Jelena Vukov, P.E.Apex Environmental, Inc.269 Great Valley ParkwayMalvern, PA 19355Tel. (610) 722-9050Fax. (610) 722-9010jvukov@apexenv-pa.com