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