FLOWABLE FILL USING GLASS CULLET PENNDOT’s Glass Cullet Workshop December 2003 Strategic Environmental Management Program Office

Presented by:

Jelena Vukov, PE Apex Environmental, Inc.

Flowable Fill – Definition: Flowable Fill is also known as: 9 Controlled Low-Strength Material 9 Unshrinkable fill 9 Controlled Density Fill 9 Flowable mortar 9 Flowable 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 Cement

50-200 lbs/yd3

Strength and hardening times

Fly ash Provides flowability

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

Aggregate filler

Aggregate Fine aggregate

2600-3100 lbs/yd3

Coarse Aggregate

Typically 50% mix of total aggregates

Water

325-580 lbs/yd3 (with aggregates)

Higher content that in concrete mixes

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 Fill Advantages 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 nonexistent 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 Comparisons Flowable Fill vs. Conventional Aggregate Source: Hennis and Frishette, 1990

Flowable Fill

Units Required

Price/ Unit

Price

2.2 m

$49.92

$109.82

2.2 m

$50.18

$110.40

$100.10

$220.22

Backfill: Flowable Fill (including supervisor and labor) Asphalt Fill: Fill Truck Total

Cost Comparisons Flowable Fill vs. Conventional Aggregate Aggregate (conventional) Fill with Plate and Permanent Trench

Units Required

Price/ Unit

Price

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

$7.00

Supervisor

1 hour

$24.20

$24.20

Steel Plates

2

$50.00

$100.00

2.2 m

$50.18

$110.40

$167.19

$367.81

Backfill: #57 Stone

Asphalt Fill: Fill Truck Total

Source: Hennis and Frishette, 1999

Flowable Fill Cost Components Concrete Material Costs:

Flowable Fill Costs:

Cement: $22/ m3

Cement - $4 / m3

Fine Aggregate: $6/ m3

Aggregate Filler: $10.5/m3

Coarse Aggregate: $8/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 PENNDOT Construction 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 Backfill 220.2 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 A Mix Design Properties & Criteria

Type A

Type B

Type C

Type D

45 (100)

23 (50)

68-90 (150-200)

136-320 (300-700)

910 (2000)

136 (300)

136 (300)

45-180 (100-400)

0

1180 (2600)

1180 (2600)

**

178 (7) min

178 (7) min

178 (7) min

178 (7) min

AASHTO T 121, C 136

****

****

****

****

Density (kg/m3 (pcf))

N/A

N/A

N/A

480-1120 (30-70)

Mix Design (/m3(/CY) Cement (kg/(lbs))* Pozzolans (kg/(lbs))* Bottom ash (kg/(lbs))* Or Coarse Aggregate Or Fine Aggregate Air Generating Admixture Slump (mm (inches))

AASHTO T121, C 136 Water Absorption of

Or as specified --

--

--

--

0.86

0.86

5.51 (800) min

0.62-2.75 (90-400)

(125) max

(125) max

Aggregate AASHTO T 85 Comprehensive Strength (Mpa (psi)) PTM No. 604 28 Days

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 coproduct materials in flowable fill.

Pennsylvania State University & Pennsylvania Transportation Institute Study

Materials tested: 9Fly ash 9Spent Foundry Sand 9Glass Cullet (Fine and Coarse) 9Reclaimed 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 A

Type B

Section 220Table A

Section 220Table A

Cement

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: Sieve Size

Percent Passing

3/8 inch (9.5 mm)

100

No. 4 (4.75 mm)

100

No. 8 (2.36 mm)

80

No. 16 (1.18 mm)

50

No. 30 (600um)

30

No. 50 (300 um)

15

No. 100 (150 um)

5

Absorption: 1.3% Specific Gravity: 2.29 Debris Level: 0% Used in Type A & Type B Flowable Fill Design Mixes Source: Dec. 1999, Final Report

Design Mix Results Type A – Glass Cullet Mix

Type B – Glass Cullet Mix

No Segregation

No Segregation

W/C = 4.4

W/C = 9.2

Bleeding = 0

Bleeding = 102 ml (3-hr)

Plastic Density (1,950 kg/m3)

Plastic Density (1,920 kg/m3)

Initial Set (hr) = 5.17 hr

Initial Set (hr) = 4.92 hr

Compressive Strength

Compressive Strength

= 1.02 Mpa (28-day)

= 0.46 Mpa (28-day)

Study Conclusions General 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: