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Geotechnical Evaluation of Crushed Glassfor Transportation Applications
PENNDOT Sponsorship
Apex holds multiple environmental services contracts with PENNDOTApex Technical Assistance to Strategic Environmental Management (SEM) Program Office.Implementing PENNDOT Strategic Recycling Plan: Research, specifications, project development, communications, contracting.Use of recycled materials on maintenance and construction projectsDrexel University, University of Maine partners
Local (PA) Crushed Glass (CG) Sources
Processed crushed glass cullet stockpile at Southeastern PA quarry (Supplier I).
Unprocessed glass cullet stockpile at Eastern PA recycling facility (Supplier II).
Three tested conditions:
AR: As ReceivedCF: Coarse Fraction (> No. 8 sieve)PC: Post Compaction
Grain Size Distributions for CG
10 1 0.1 0.01Grain size (mm)
0
20
40
60
80
100
Per
cent
fine
r by
wei
ght
gravel(fine)
sandfines (silt or clay)
finemediumcoarse
Range of Supplier I sieve analyses data (4 tests)
Range of Supplier II sieve analyses data (4 tests)
Supplier I hydrometer data (single test)
Supplier II hydrometer data (single test)
USCS grain size catorgories
Compaction-induced grain size changes by Modified Proctor test
10 1 0.1 0.01Grain size (mm)
0
20
40
60
80
100
Per
cent
fine
r by
wei
ght
Supplier I - As-recievedSupplier I - Post-compactionSupplier II - As-recievedSupplier II - Post-compaction
-4
0
4
8
12
Cha
nge
in p
erce
nt p
assi
ng (%
)
gravel(fine)
sandfines (silt or clay)
finemediumcoarse
USCS grain size catorgories
Supplier I
Supplier II
Grain size indices and Cu as a function of freeze-thaw cycles for CG
0 20 40 60 80 100 120
Number of freeze-thaw cycles
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Gra
in s
ize
(mm
)
D10
D50
D60 range of as-recieved D60
range of as-recieved D50
range of as-recieved D10
4
6
8
10
Coe
f. of
uni
f. (C
u)
Cu range of as-recieved Cu
Supplier I
Grain size indices and Cu as a function of freeze-thaw cycles for CG
0 20 40 60 80 100 120
Number of freeze-thaw cycles
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Gra
in s
ize
(mm
)
D10
D50
D60range of as-recieved D60
range of as-recieved D50
range of as-recieved D10
4
6
8
10
Coe
f of u
nif.
(Cu)
Cu
range of as-recieved Cu
Supplier II
Physical and Durability Characteristics
Supplier I Supplier II
AR CF PC AR CF
- -
-
-
-
GP
No. 8
-
-
-
-
-
GP
No. 8
-
-
PC
Water Content ASTMD2216-98 2.36 - 4.22 -
Debris Content gravimetric 0.34 - 1.82 -
Coef. of uniformity, Cu -- 6.2 6.5 7.2 7.8
Specific gravity, GsASTM
C127-88 2.48 - 2.49 -
USCS classification ASTMD2487-98 SW SW SW SW-SM
AASHTO classification AASHTOM43-88 No. 10 No. 10 No. 10 No. 10
LA Abrasion, wt% ASTMC131-96 24 - 25 -
Sodium Sulfate Soundness, wt%
ASTMC88-99 6.38 - 7.1 -
Test/Index Test standard
Standard and Modified Proctor compaction results on CG
0 4 8 12 16 20Water content (%)
15
16
17
18
19
20
21D
ry d
ensi
ty (k
N/m
3 )
zero air voidsGs = 2.485
Supplier IModified Proctor
Supplier IIModified Proctor
Supplier IStandard Proctor
Supplier IIStandard Proctor
zero air voidsGs = 2.65
Supplier I
Supplier II
Failure envelope from Direct Shear tests on compacted CG
0 50 100 150 200
Normal stress (kPa)
0
50
100
150
200
250
300
350
She
ar s
tress
(kP
a)
Supplier I
Supplier II
Failed Triaxial Shear CG sample
Triaxial Stress and volume change behavior versus axial strain
0
200
400
600
800
Dev
iato
r stre
ss (k
Pa)
(27.6 kPa)
0 5 10 15 20Axial strain (%)
-8
-6
-4
-2
0
2
Vol
umet
ric s
train
(%)
(27.6 kPa)
(85.2 kPa)
(85.2 kPa)
(141.3 kPa)
(141.3 kPa)
Supplier I
Triaxial Stress and volume change behavior versus axial strain
0
200
400
600
800
Dev
iato
r stre
ss (k
Pa)
(27.6 kPa)
0 5 10 15 20Axial strain (%)
-8
-6
-4
-2
0
2
Vol
umet
ric s
train
(%)
(27.6 kPa)
(85.2 kPa)
(85.2 kPa)
(141.3 kPa)
(141.3 kPa)
Supplier II
Summary of Engineering Properties of Crushed Glass
Supplier I Supplier II
AR CF AR CF
Modified Proctorγd,max, kN/m3
wopt, %
ASTMD1557-00
18.39.7
17.07.8
17.511.2
17.19.9
Standard Proctorγd,max, kN/m3
wopt, %
ASTM D698-00
16.812.8
14.76.5
16.613.6
15.612
Direct Shear1
Internal Friction, degreesσn, kPa
0-6060-120
120-200
ASTM D3080-98
61° - 63°
58° - 61°
63° - 68°
-54°
-
59° - 62°
55° - 59°
47° - 55°
-48°
-
Consolidated Drained Triaxial1
Internal Friction, degrees
USACE 48° 45° 47° 44°
Hydraulic ConductivityK, cm/s (*1000)
ASTMD2434-68 0.161 0.722 0.645 0.491
Test/Index Test standard
Summary of TCLP and SPLP test results on CG
TCLP SPLPHW
Designation Supplier I Supplier II Supplier I Supplier II
Arsenic 0.05 5.0
100
1.0
5.0
5.0
0.2
1.0
5.0
<0.10 <0.10 <0.10 <0.10
Mercury 0.002 <0.0002 <0.0002 0.00024 <0.0002
Selenium 0.05 <0.20 <0.20 <0.20 <0.20
Silver 0.05 <0.02 <0.02 <0.02 <0.02
Barium 2.0 0.151 <0.10 <0.10 <0.10
Cadmium 0.005 <0.10 <0.10 <0.10 <0.10
Chromium 0.1 <0.03 0.0772 <0.03 <0.03
Lead 0.015 <0.10 0.128 <0.10 <0.10
Test/Index
USEPA Drinking
Water standard
All data in milligrams/liter
Crushed Glass Applications
•Base Course
•Subbase
•Embankments
•Structural Fill
•Nonstructural Fill
•Utility Bedding and Backfill
•Retaining Wall Backfill
•Vapor Extraction Trenches
•Foundation Drainage
•Drainage Blankets
•Frenc
•Sand Filters (Wastewater)
•Well Packing Media
•Septage
•Leachate
•Antiskid material?
h/Interceptor Drains
Field Media
Collection Media
Crushed Glass Projects
Installation of 2,000 tons of glass cullet between jersey barrier and sound wall along I-95 in Tinicum, Delaware County.
Glass-Soil Blending Study
Concern:
CG has excellent strength but, “modest” cohesion of the CG suggested potential instability of shallow utility trenches and excavations.
Action:
Evaluated how soil blending could improve the cohesion characteristics of CG
Evaluated how glass blending improved the geotechnical characteristics of marginal soils (quarry fines, spoils).
Focus of the Laboratory Investigation
CG (Supplier I only) was blended with two clayey soils to evaluate improvement in cohesion.
• Kaolin Clay• Silty Sand from King of Prussia, PA
A variety of marginal soils were blended with CG to evaluate improvement in strength characteristics.
• (K) Kaolinite• (KP) King of Prussia soil• (QF) Quarry Fines (sandy silt)• (QS) Quarry Screenings (coarse to fine sand)
Atterberg Limit Comparison
LL PL PI
K Soil 48 28 20
KP Soil 24 21 3
QF soil 21 20 1
QS soil - - Nonplastic
CG - - Nonplastic
USCS Classifications of Soil and Soil-Glass Specimens
Blend CG K Soil KP Soil QF Soil QS Soil
As-received (100% soil)
SW ML SW CL/ML SP
50% soil - SM SW SM-SC SW
35% soil - SM SW SM SW
20% soil - SM SW SM SW
10% soil - SM SW SM SW
Gradation of K, CG and K-CG blends
100 10 1 0.1 0.01 0.001Grain Size (mm)
0
20
40
60
80
100
Per
cent
Fin
er
100% CG10% K soil20% K soil35% K soil 50% K soil100% K soil
gravel sand silt or clay
Modified Proctor for K, CG and K-CG blends
0 10 20 30 40water content (%)
13
14
15
16
17
18
19
20
21dr
y de
nsity
(kN
/m3 )
100% CG10% K soil20% K soil35% K soil50% K soil100% K soil
90
100
110
120
130
dry
dens
ity (l
b/ft3 )
zero aid voidsGs = 2.48
zero aid voidsGs = 2.70
Gradation of KP, CG and KP-CG blends
100 10 1 0.1 0.01 0.001Grain Size (mm)
0
20
40
60
80
100
Per
cent
Fin
er
100% CG10% KP soil20% KP soil35% KP soil50% KP soil100% KP soil
gravel sand silt or clay
Modified Proctor for KP, CG and KP-CG blends
0 10 20 30 40water content (%)
13
14
15
16
17
18
19
20
21dr
y de
nsity
(kN
/m3 )
100% CG10% KP soil20% KP soil35% KP soil50% KP soil100% KP soil
90
100
110
120
130
dry
dens
ity (l
b/ft3 )
zero aid voidsGs = 2.48
zero aid voidsGs = 2.70
Gradation of QF, CG and QF-CG blends
100 10 1 0.1 0.01 0.001Grain Size (mm)
0
20
40
60
80
100
Per
cent
Fin
er
100% CG10% QF soil20% QF soil35% QF soil50% QF soil100% QF soil
gravel sand silt or clay
Modified Proctor for QF, CG and QF-CG blends
0 10 20 30 40water content (%)
13
14
15
16
17
18
19
20
21dr
y de
nsity
(kN
/m3 )
100% CG10% QF soil20% QF soil35% QF soil50% QF soil100% QF soil
90
100
110
120
130
dry
dens
ity (l
b/ft3 )
zero aid voidsGs = 2.48
zero aid voidsGs = 2.70
Maximum Soil Density (ASTM D1557) vs. Soil Content
0 20 40 60 80 100percent soil
15
16
17
18
19
20
21
22
23
Max
imum
Dry
Den
sity
(kN
/m3)
p
K soilKP soilQF soilQS soilCG - current dataCG - previous data
Optimum Moisture Content (ASTM D1557) vs. Soil Content
p
0 20 40 60 80 100percent soil
6
8
10
12
14
16
Opt
imum
Wat
er C
onte
nt (%
) K soilKP soilQF soilQS soilCG - current dataCG - previous data
Direct Shear Friction Angle vs. Soil Content
0 20 40 60 80 100percent soil
2024283236404448525660
phi
range of CG valuesK soilKP soilQF soilQS soilCG
Direct Shear Cohesion vs. Soil Content
0 20 40 60 80 100percent soil
0
10
20
30
40
50
cohe
sion
(KP
a)
K soilKP soilQF soilQS soilCG
Blending Study Findings
Minor blending (<10%) with other soils adds sufficient cohesion to CG for construction. CG blended with marginal soils demonstrated significantly improved geotechnical characteristicsUse of CG improves soils previously unacceptable forPennDOT construction applications including Safe Fill requirementsCG can be utilized in blends for inexpensive embankment fills, especially in metro areasPositive Implications for bearing capacity and slope stability (see next slides)
Direct Shear General Bearing Capacity Factors for K, CG and K-CG Blends (after Vesic)
1
10
100
1000
0 5 10 15 20 25 30 35 40 45 50
Soil Friction Angle, (deg)
Bea
ring
Cap
acity
Fac
tors
,
N γ
φ
N c
N q
N
Nc , N
q , N
γ
For φ = 0 N c = 5.14 N q = 1 N γ = 0
K
50-50
CG(min)
φ = 24 N c = 17 N q = 7 N γ = 6
φ = 36 N c = 38 N q = 26 N γ = 35
φ = 46 N c = 116 N q = 117 N γ = 134
Undrained Factor of Safety on Deep Seated Rotational Stability, PENNDOT Tarrtown Bridge, 100% Soil Embankment
Undrained Factor of Safety on Deep Seated Rotational Stability, PENNDOT Tarrtown Bridge, 100% Crushed Glass Core
Undrained Factor of Safety on Deep Seated Rotational Stability, PENNDOT Tarrtown Bridge, Tire Shred Layers
CG Research Sponsor:Kenneth J. Thornton, P.G.Chief, Pollution Prevention Section400 North StreetHarrisburg, PA 17105