Asphalt Characterization Utilizing Gel Permeation ... William.pdf · Asphalt Characterization...

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Asphalt Characterization Utilizing Gel Permeation Chromatography (GPC) 1 William Daly , 1 Ionela Glover, 1 Ioan Negulescu, 2 Christopher Abadie, 1,2 Louay Mohammad, and 1 Rafael Cueto 1 Louisiana State University and 2 Louisiana Transportation Research Center Baton Rouge, LA

Transcript of Asphalt Characterization Utilizing Gel Permeation ... William.pdf · Asphalt Characterization...

Asphalt Characterization

Utilizing Gel Permeation Chromatography (GPC)

1William Daly, 1Ionela Glover, 1Ioan Negulescu, 2Christopher Abadie,1,2Louay Mohammad, and

1Rafael Cueto1 Louisiana State University and

2Louisiana Transportation Research CenterBaton Rouge, LA

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The Co-authors

Ionela Glover

Louay Mohammad Rafael Cueto

Chris AbadieIoan Negulescu

Down the Road, Asphalt Cement Preparation

Sequence of Binder Samples Studied

1.BinderRefinery

2.Binder Hot Mix Asphalt

Plant (tank)

3.Binder Extracted from

HMA Plant : Mixture

Binder+Agg.+RAP

4.Binder Extracted from

HMA (after transport)

5.Binder Extracted from

Fresh Road Cores

6.Binder Extracted from

Road Cores after 6 months

7.After 12 months

8.After 18 months

RAP, ultimate aged binder

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Asphalt Binder Extraction

6”

Residue dried in vacuo at staged temperatures

GPC Sample Preparation

2% concentrationin THF

3-5 mLsyringe

PTFE 45µmFilter Removes insolubles

1.5 mL vial

~ 0.2 g Sample

Principle of Gel Permeation Chromatography (GPC) Separation and Data Analysis

A mechanical pump provides an eluting solvent from reservoir to push the injected sample along in columns at constant rate. The individual molecules wander around, and sometimes enter the pores of the column packing material (a gel).

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GPC

• GPC separates molecules on the basis of size (like sieving!).

• When a mixture of molecules dissolved in a solvent is applied to the top of the column, the smaller molecules are distributed through a larger volume of gel than is available to the large molecules. Consequently, the large molecules move more rapidly through the column, and in this way the mixture can be separated (fractionated) into its components.

*http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/ExclusionChrom.html

Calibration of GPC Columns with Polystyrene Standards

1000

10000

100000

Y =658.32034-1428.41445 X+1045.39085 X2-256.47616 X3

log M

w

log Ve

polystyrene standards Data1A

12 14 16 18 20 22 24 26 28 30 32 34-1

0

1

2

3

4

5

6

7

8

MW=1,940 D

MW=9,920 D

MW=218,800 D

MW=52,400 D

MW=19,980 D

MW=523,000 D

17.16ml17.84ml18.52ml19.14ml19.78ml

23.51ml21.91ml

25.30ml27.48ml

∆RI (

rel)

Elution Volume, ml

MW=1,060D MW=1,940D MW=4,920D MW=9,920D MW=19,980D MW=52,400D MW=66,350D MW=96,000D MW=218,800D MW=523,000D

28.94ml

MW=1,060 D

Decreasing MW

Log Mw

Typical PMAC GPC Chromatogram

20 25 30 35 400.0

5.0x10-6

1.0x10-5

1.5x10-5

2.0x10-5

2.5x10-5

DR

I sig

nal

Time,min PMAC

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Schematic oxidative aging representation

of polymer

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

0.0

0.5

1.0

1.5

~650K

HMW 17.7 - 20 mL SPECIES 100 - 50 K

LMW 26 - 31 mL SPECIES 3 - 0.4 K

MMW 20 - 26 mL SPECIES 50 - 3 K

VHMW 16 - 17.7 mL SPECIES 650 - 100 K

~50K~70K ~20K

DRI

Ve, mL

Polymer (original) Polymer (TFOT) Polymer (PAV)

Insoluble gel forms

During Aging Displacement of Maltenes Leads to Asphaltene aggregation

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Separation of PMAC Components by Molecular Weight

H2C C

H

H2C

HC

x

HC

H2CC

H

H2C

y x

Low Molecular

WeightMaltenes3-0.2 kDa

MediumMolecular

Weight45-19kDa

High Molecular

WeightSBS Polymer

800-45kDa

Asphaltenes19-3 kDa

Division of PMAC Components by Molecular Weight

DRI s

ignal

Mw kDa PMAC

VHMw

800-300

HMw

300-45

MMw

45-19

Asphaltenes19-3

Maltenes3-0.2

Sum

Relative concentration reported as % fraction from integrated area

Project from Supplier A

19-3K 3-0.2K

Sum Asphaltenes Maltenes

3.1%

17%

80%

3.4%

23%

74%

2.8%

20%

78%

A refinery 76-22 A core new road A core after 6 months service

Plant Mixture

RAP

Insolubility THF

2-7%

Project from Supplier A

19-3K 3-0.2K

Sum Asphaltenes Maltenes

3.1%

17%

80%

3.4%

23%

74%

2.8%

20%

78%

A refinery 76-22

A core new road

A core after 6 months service

Corrected Data

27%25%

71%72%

78%

RAP data not available

19%

Project from Supplier B

1000-19kDa 19-3kDa 3-0.2kDa

Sum Mw Asphaltenes Maltenes

2.1%

16%

82%

2.4%

16%

82%

1.7%

25%

73%

3.4%

20%

77%

3.4%

19%

77%

3.2%

20%

77%

B refinery 76-22

B plant 76-22

RAP

B mix plant

B mix road

B cores new road

17%

81%

74%

24%Corrected Data

6 month data comparable to fresh road data

Project from Supplier C

1000-19kDa 19-3kDa 3-0.2kDa

Sum Mw Asphaltenes Maltenes

2.9%

14%

83%

2.1%

14%

84%

1.4%

23%

76%

2.3%

19%

79%

2.2%

17%

81%

2.4%

18%

80%

C refinery 76-22

C plant 76-22

RAP

C mix plant

C mix road

C cores new road

78%

21%

21%

16%Corrected Data

6 month data comparable to fresh road data

Project from Supplier D

1000-19kDa 19-3kDa 3-0.2kDa

Sum Mw Asphaltenes Maltenes

1.7% 15%

83%

3.9%

16%

80%

2.8%

27%

70%

4.2%

23%

73%

4.6%

23%

72%

4.1%

23%

73%

D refinery wrong label 76-22

D plant 76-22

RAP

D mix plant

D mix road

D cores new road

70-22

28%

78%

66%

18%

Corrected Data

PMAC 76-22

1000-19kDa 19-3kDa 3-0.2kDa

Sum Mw Asphaltenes Maltenes

3.1%

17%

80%

2.1%

16%

82%

2.9%

14%

83%

3.9%

16%

80%

supplier A

supplier B

supplier C

supplier D

Conclusions

• GPC is a simple quantitative method for asphalt characterization• Processing has less impact on properties than RTFO predicts• Significant changes in composition were not observed during the

processing sequence unless RAP is added• RAP can be considered a long-term-field-aged sample• RAP varies significant depending on source• Some RAP may still contain polymer• RAP might have significant impact on field properties because of

enhanced asphaltene content• Preliminary 6 month data does not show significant aging in terms

of composition

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Thank You ,Any Questions?

30 25 20 15 10 5 0-0.02

0.00

0.02

0.04

0.06

0.08

0 5 10 15 20 25 30

-1

0

1

2

3

4

5

6

7

8

9

10

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Log

MW

∆RI

Flowing (Elution) Time (or Volume), min (ml)

AC30 +3% SBS TFOT

MW 120,000

MW 750MW 9,000

Decreasing MW

The large difference (ca. two orders of magnitude) between the molecular mass of polymer molecules and the mass of asphalt components allows the visualization of the polymer through a size exclusion analysis, such as gel permeation chromatography (GPC).

LTRC

General scheme for a GPC experiment

Principle of GPC Separation and Data Analysis

A mechanical pump provides an eluting solvent from reservoir to push the injected sample along in columns. The individual molecules wander around, and sometimes enter the pores of the column packing material (a gel).

•6 month data comparable to fresh road data