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: <2%
PENNDOT Demonstration
Field 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:
9 Unauthorized changed in design mix (ground granulated blast
furnace slag was substituted for fly ash)
9 Produced structural backfill vs. excavatable backfill
9 Suitable for sinkholes, voids, bridge abutments, but not for
pipe trench backfill.
9 Easy placement, self-compacted, final set reached in 8 hours,
could support light traffic in 24 hours.
9 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 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 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
Sieve Size
Bituminous Concrete Sand
Mortar
Sand
Type B
Type A
#1
#2
#3
Filler
Type C
9.5 mm (3/8-in)
100
100
-
100
-
-
4.75 mm (No. 4)
95-100
95-100
100
80-100
-
100
2.36 mm (No. 8)
70-100
70-100
95-100
65-100
-
95-100
1.18 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
-
-
-
-
-
Strength Ratio
Min. Percent
95
-
-
-
-
95
Soundness Test
Max. Loss %
10
15
15
15
-
10
2.3-3.15
-
-
-
-
1.6-2.5
Fineness
Modulus
Glass
Cullet
(aver.)
Ave. 2.0
6.3-7.1
Section 703.2 - TABLE B
COARSE AGGREGATE - Quality Requirements
Type A
Type B
Type C
Glass
Cullet
Soundness, Max. %
10
12
20
6.38-7.1
Abrasion, Max. %
45
45
55
24-25
Thin and Elongated Pieces, Max. %
15
20
-
Material <75 µm (No. 200), Max. %
*
*
10
1.2-3.2
Crushed Fragments, Min. %
55**
55**
50
N/A
Compacted Density (Unit Weight), Min. kg/m3
(lbs./cu.ft.)
1100 (70)
1100 (70)
1100
(70)
(72-79)
Deleterious Shale, Max. %
2
2
10
N/A
Clay Lumps, Max. %
0.25
0.25
3
N/A
Friable Particles, Max. % (excluding shale)
1.0
1.0
-
N/A
Coal or Coke, Max. %
1
1
5
N/A
Glassy Particles, Max. %
4 or 10***
4 or 10***
-
100
Iron, Max. %
3*****
3*****
3*****
N/A
Absorption, Max. %
3.0****
3.5****
-
1.3
2
s
15
N/A
Gradation – AASHTO #10
Total Deleterious Shale, Clay, Lumps, Friable
Particles, Coal, or Coke Allowed, Max. %
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
9(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 Backfill
220.2 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 Backfill
220.2 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 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)
1180 (2600)
45-180 (100-400)
0
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
N/A
--
--
--
--
0.86 (125)
max
0.86 (125)
max
5.51 (800) max
0.62-2.75 (90-400)
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
Aggregate AASHTO T 85
Comprehensive Strength
(Mpa (psi))
PTM No. 604 28 Days
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 application
FUTURE OBJECTIVES:
• ? Revisions to existing Pub. 408 specifications
• ? PENNDOT Provisional Specifications
Contact Information
Jelena Vukov, P.E.
Kenneth J. Thornton, PG
Apex Environmental, Inc.
Chief, Pollution Prevention Section
269 Great Valley Parkway
P.O. Box 400
Malvern, PA 19355
Harrisburg, PA 17105
Tel. (610) 722-9050
Fax. (610) 722-9010
jvukov@apexenv-pa.com