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MD. Sahadat Hossain, Ph.D., P.E.Professor of Civil Engineering, The University of Texas at Arlington (UTA)

Sadik Khan, Ph.D., P.E., Assistant Professor, Jackson State University

Asif Ahmed and Ashrafuzzaman KhanGraduate Students (UTA)

Case Studies: Long Term Performance of Highway Slopes Stabilized with Recycled Plastic Pin

Fact About Plastic Bottles!

• 50 Billion Water Bottle end up in US Landfill Each Year

• It takes 700 year to decompose plastic bottles

• Ecosystems and wildlife are negatively impacted by plastic debris.

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• Recycled Plastic Pin (RPP)

• Mainly Polymeric Materials

• Fabricated from Recycled Plastics

• Advantages

• Commercially Available

• Use of RPP Reduces Waste Volume

• Resistant to Biological Exposure

• Typical Composition

• HDPE : 55-90%

• LDPE : 5-10%

• PP, PET, PS : 1% - 10%

• Misc. : 0 – 5%

A 10’ long RPP can replace 500 Soda Bottles

Factor of Safety:Without ReinforcementFS = Mr/Md

Factor of Safety:With ReinforcementFS = (Mr+∆Mr)/Md

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Interstate 30

US 287 US 67

Site Location

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0

10

20

30

40

50

60

70

80

20 40 60 80

Pla

stic

ity

Ind

ex

Liquid Limit

Plasticity Chart

BH-1BH-2BH-3

Bore Hole Location

Depth of Sample

Liquid LimitPlasticity

IndexBH-1 5 48 25BH-1 10 60 33BH-1 15 72 48BH-1 20 64 38BH-2 5 49 26BH-2 10 67 38BH-2 15 73 45BH-2 20 61 35BH-2 25 62 37BH-3 5 52 27BH-3 10 61 34BH-3 15 79 51BH-3 20 58 32BH-3 25 62 40

RI-1

RI-2

Resistivity Profile: RI-1

Resistivity Profile: RI-1

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0

1

2

3

4

5

6

7

8

9

10.00 20.00 30.00 40.00

Dep

th o

f S

amp

le (

m)

Moisture Content (%)

Moisture Variation along the borehole

US 287 BH1 US 287 BH2

0

1

2

3

4

5

6

7

8

0 5 10 15 20 25

Dep

th (

m)

Resistivity (Ohm-m)

Variation of Resistivity

BH-1 BH-2 BH-3

Soil Type

Friction Angle

CohesionUnit

WeightElastic

Modulus

φ c ϒ E

- ◦ psf pcf psf

1 10 100 125 100000

2 23 100 125 150000

3 15 250 130 200000

4 35 3000 140 250000

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March 2011 March 2012

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Reinforced Section 1

Reinforced Section 2 Reinforced Section 3

Reinforced Section 1: FS = 1.43

Reinforced Section 2: FS = 1.48

Reinforced Section 3: FS = 1.54

Soil Type

Friction Angle

CohesionUnit

WeightElastic

Modulus

φ c ϒ E- ◦ psf pcf psf1 10 100 125 1000002 23 100 125 1500003 15 250 130 2000004 35 3000 140 250000

Back Analysis of Unreinforced Slope: FS = 1.05

Soil 4

Soil 3

Soil 2 Soil 1 Back Calculated Soil Parameters

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• Equipment: Klemm 802 Drill Rig

• Hammer Type: KD 1101

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Section No. ofRPP

Installation Time(Day)

Start Date

FinishedDate

Reinforced Section 1

192 2 March 01, 2011

March 03, 2011

Reinforced Section 2

225 2 March 04, 2011

March 05, 2011

Reinforced Section 3

238 3 Feb 29, 2012

March 6, 2012

Total RPP 655, Replaced 330000 Plastic Bottles from Landfill

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• Rain Gauge

• Instrumented RPP

• Surveying

• Inclinometer

• Moisture Sensor

• Water Potential Probe

Instrumentation

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0.0

4.0

8.0

12.0

16.0

0 50 100 150 200 250

Set

tlem

ent

(in

)

Distance along Roadway (ft)

6.6.12 10.6.12 12.13.12 7.1.13 5.15.14 12.24.14 6.18.15 12.15.2015 6.15.2016

Settlement at the crest of slope: US 287

R - 01 R - 02 R - 03

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-0.5

0

0.5

1

1.5

2

2.5

3

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dis

pla

cem

ent

(in

ch)

Rai

nfa

ll (i

nch

)

Date

Inclinometer - 1 : Cum Displacement A-A with Time

Rainfall 4.5 (ft) 6.5 (ft) 8.5 (ft) 10.5 (ft) 12.5 (ft)

14.5 (ft) 16.5 (ft) 18.5 (ft) 20.5 (ft) 22.5 (ft)

Movement during the failure of Northbound slope

Movement during the failure of Northbound slope

Expansive Behavior

-0.500.511.52

406080

100120140

1/1/

122/

1/12

3/1/

124/

1/12

5/1/

126/

1/12

7/1/

128/

1/12

9/1/

1210

/1/1

211

/1/1

212

/1/1

21/

1/13

2/1/

133/

1/13

4/1/

135/

1/13

6/1/

137/

1/13

8/1/

13

Dis

pla

cem

ent

(in

ch)

Dai

ly H

igh

est

Tem

per

atu

re

(F)

Date

Comparison of Horizontal Movement with Temperature

Daily Highest Temperature 2.5 ft-Inc1 2.5 ft-Inc 3

Desiccation Crack (Dry Period)

No Cracks (Wet Period)

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R. Section 1

Control Section

Control Section 2

R. Section 3

Settlement: 15 in

Settlement: 9 in

Settlement at Control Section

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News and Media

Failure Location 3

Failure Location 4

Failure Location Time

Failure Location-1 October 2013

Failure Location -2 October 2013

Failure Location-3 June 2015

Failure Location-4 June 2015

Failure Location 1 Failure Location 2

Failure Location 3

Comparison of Performance Northbound and Southbound (Reinforced) Slope

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North Side

September 2015

October 2015

Soil Nailed Wall

Southbound slope (RPP stabilized)

Northbound slope

(after construction of soil nail wall)

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0123456

Pre

cip

itat

ion

(in

ch)

Date

Failure of Northbound Slope After Repair

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FS = 1.74

No of RPP: 336

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35

Instrumentation 

TypeNumber

Monitoring and 

Data Collection

Inclinometer 3 Bi‐weekly

RPP Survey

4 lines

(Approx 90 

survey points)

Monthly

Contour Survey Entire Slope Quarterly

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No of RPP: 425

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• RPP provided resistance against shallow slope failure

• A Crawler-Mounted Rig, Equipped with a Mast-Mounted Pseudo Vibratory Hammer, Worked Effectively to Install RPPs

• On Average, a RPP Can be Installed within 4 Minutes, and a Total of 100 to 120 RPPs can be Installed in a Single Day.

• Settlement at Control Section is 15 inch

• Settlement at Reinforced Section 1 is 2.5 inch.

• Closer RPP Spacing at Crest Provided Higher Resistance against Slope Deformation

• RPP can save the stabilization cost up to 60% - 80% of conventional technique, and have potential to be a effective sustainable alternative to stabilize shallow slope failure.

Summary and Conclusion

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Upcoming Book

Thank You