S28 Asphalt GPC Testing LTC2013

7/29/2019 S28 Asphalt GPC Testing LTC2013

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Verification of PG Asphalt Polymer

Properties using Gel Permeation

Chromatograph (GPC)

By

Michael Grubb & Golden Hwaung


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Performance-Graded (PG) Asphalt

Asphalt was previously graded by penetration orviscosity

SHRP (Strategic Highway Research Program)developed Performance Graded specifications

Performance grade is based on regional climaticconditions

Louisiana began using PG specifications in the

late 1990s Regional grade is PG 64-22 adjusted upward

based on traffic loading (to PG 70-22 and 76-22)


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Performance-Graded (PG) Asphalt

PG 64 Asphalt (64C) - typically no polymer

PG 70 Asphalt (70C) - typically 2%+

PG 76 Asphalt (76C) - typically 3%+

polymer content = deformation resistance


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How can we?

Verify polymer content

Verify polymer quality

Observe difference between companies

GPC


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GPC

GPC-Gel PermeationChromatography

Uses RI (refractive index)detector

RI - measure of how light (orany radiation) passes throughan object.

Molecular Weight RI sensorcan detect changes in

molecular weight Enables the calculation of

polymer content in an asphaltsample


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How does GPC Work

Molecular separation

based on particle size

Separation occurs via

the use of porous beadspacked in a column

THF: Tetrahydrofuran

RI sensor: RefractiveIndex sensor


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1

/

12.657

2

/

17.34

3

/

19.84 Peak No.

Retention time

Intensity

Time


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What is the GPC used for?

Measures the percent of each group of

chemical: For example PG76, it can show the

percent of polymer, asphaltene and maltene.

Determines the molecular weight of unknown

polymer.

It can be used as a spectrometer (Hydro Straw

and Guar Plus Mulch).


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1

/

12.657

2

/

17.34

3

/

19.84 Peak No.

Retention time

Peak 1

Polymer

>19000

Peak 2

Asphaltene

3000-19000

Peak 3

Maltene


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What is the GPC used for?

Log M =at+bt+ct+d-----(E)

Standard B has 5 peaks

Standard E has 4 peaks Standard F has 7 peaks

Each peak P(t,M)


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1

/

12.657

2

/

17.34

3

/

19.84 Peak No.

Retention time

Peak 1

Polymer

>19000

Peak 2

Asphaltene

3000-19000

Peak 3

Maltene


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Result of molecular weight calculation (RI)

[min] [mV] [mol]Mn

54,809

Peak start 10.898 0.008

1,820,589Mw

108,441

Peak top 12.657 0.908

94,911Mz

244,629

Peak end 14.125 0.546

19,337Mz+1

523,132

Mv108,441

Height

[mV]

0.898Mp

19,535

Area

[mV*sec]

90.761Mz/Mw 2.256

Area% [%] 3.288Mw/Mn

1.979

[eta] 108440.79565Mz+1/Mw

4.824

[min] [mV] [mol] Mn 4,685

Peak start 14.125 0.546

19,337 Mw 5,692

Peak top 17.348 4.808 2,996 Mz 7,408

Peak end 17.352 4.803 2,992 Mz+1 9,727

Mv 5,692

Height

[mV]

4.794

Mp 2,997

Area

[mV*sec]

434.782

Mz/Mw1.302

Area% [%] 15.752Mw/Mn

1.215

[eta] 5692.09729

Mz+1/Mw1.709

[min] [mV] [mol] Mn 853

Peak start 17.352 4.803 2,992 Mw 1,232

Peak top 19.842 11.854 963 Mz 1,617Peak end 21.598 4.921 261 Mz+1 1,925

Mv 1,232

Height

[mV]

11.838Mp 1,267

Area

[mV*sec]

2234.632Mz/Mw

1.313

Area% [%] 80.960Mw/Mn

1.445

[eta] 1231.91956Mz+1/Mw

1.563

Peak 1 Base Peak Peak 2 Base Peak

Peak 3 Base Peak


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Future Research

R = 0.3116

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

0.00% 1.00% 2.00% 3.00% 4.00% 5.00% 6.00%

G*/sin()

Polymer %

Polymer % vs. DSR G*/sin( )

Polymer % vs. DSR

Linear (Polymer % vs. DSR)


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Future Research

R = 0.3579

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00%

G*/sin()

(A/M)*(Polymer%)

(Ratio of A/M)*(Polymer%) vs. DSR G*/sin( )

Series1

Linear (Series1)


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Future Research

0.00%

1.00%

2.00%

3.00%

4.00%

5.00%

6.00%

1 21 41 61 81

Polymer%

Polymer % of PG 70 Samples

1

2

3

4

5


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Future Research

0.00%

1.00%

2.00%

3.00%

4.00%

5.00%

6.00%

1 21 41 61 81 101

Polymer%

Polymer % of PG 76 Samples

1

2

3

4

5


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Future Research

Asphaltene:Maltene

Polymer Differences

Performance based on type of polymer

Pass/Fail test


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Conclusions

This procedure is still being researched at

LTRC/LSU in order to determine more ways it

can be utilized

A potentially fast screening test for the large

number of samples


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Questions?

Documents

S28 Asphalt GPC Testing LTC2013