Solvent Extraction-Recovery Procedures and their Effect on ... 2019_Final_rev04-29-19.pdfSolvent Extraction-Recovery Procedures and their Effect on Recovered Asphalt Properties Presenter(s):

Solvent Extraction-Recovery Procedures and their Effect on Recovered Asphalt Properties

Amma Wakefield, MASc, PEng.Canadian Regional Engineer

Asphalt Institute

Prof. Susan Tighe, CPATT/UW – Research Supervisor

April, 2019

Solvent Extraction-Recovery Procedures and their Effect on Recovered Asphalt Properties

Presenter(s):London, April 9th: Mike Aurilio, Snr. QC & Product Development Coordinator – Yellowline Asphalt Products Ltd.

GTA, April 11th: Amma Wakefield, MASc, PEng. – Canadian Regional Engineer – Asphalt InstituteSudbury, April 16th: Doubra Ambaiowei, Ph.D. – Technical Director, ORBA/OAPC

Ottawa, April 18th: Steve Goodman, Ph.D., PEng. – Gemtec Consulting Engineers and Scientists

Introduction

Asphalt binders specified based on their properties in an original state

• Performance Graded by AASHTO or ASTM

What about properties of in-situ asphalt mixtures?

• Research

• Forensic investigation

• Correct asphalt used in production

• Evaluate properties of blended asphalt binder (RAP or RAS) 3

Introduction

What options do we have to determine in-situ asphalt properties?

• Performance testing of asphalt mixture

• Physical properties of recovered asphalt• Since early 1900’s

4

Current known challenges with recovered asphalt testing:

1. Physical properties test results of recovered binders have much higher variability compared to unrecovered binders

2. The choice of procedure and solvent can have an impact on the resulting physical properties of the recovered asphalt binder

3. The effect of solvent extraction on polymer modified binders and impact on physical properties is still being investigated 5

Single lab repeatability

(d2s%) of G*/sinδ

0.0

20.0

40.0

60.0

80.0

100.0

120.0

2002 2004 2006 2008 2010 2012 2014 2016 2018

d2

s%

Year

Abson

Rotavapor

RTFO

6

NCHRP Project 09-12: RAP in Superpave System

Project Goal:

To develop guidelines for incorporating RAP in the Superpave System.

Part of research evaluated effect of different extraction-recovery procedures and solvents on high temperature properties of recovered asphalt binders

7


0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

Procedure-Solvent

G*/s

in δ

at

64 C

, k

Pa

Centrifuge

Abson

TCE

Centrifuge

Rotovapor

Toluene

SHRP

Rotovapor

TCE

SHRP

Rotovapor

Toluene

Kentucky RAP

8

Why does it matter?

Most specifications don’t identify one extraction-recovery method.

It makes a difference in acceptance/rejection of material.

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

Procedure-Solvent

G*/s

in δ

at

64 C

, k

Pa

Centrifuge

Abson

TCE

Centrifuge

Rotovapor

Toluene

SHRP

Rotovapor

TCE

SHRP

Rotovapor

Toluene

9

Research Objectives

1. Compare physical properties and testing variability of original (tank) asphalt to recovered asphalt

2. Compare laboratory aging and field aging through chemical analysis of functional groups of asphalt

10

Sample A - Terminal

Sample B – Tank Asphalt

Sample C – Plant Mix (Performance Testing)

Sample D – Job Site (Recovered)Sampling Plan

11

Asphalt Materials Collected

12

Research Objectives



13

Standard Deviation

Tank = 0.7 to 1.7

Recovered = 1.7 to 9.4

5 8 -3 4

0 R

5 8 -3 4

0 R

5 8 -3 4

1 5 R

5 8 -2 8

0 R

6 4 -2 8

0 R

7 0 -2 8

0 R

7 0 -2 8

1 5 R

4 8

5 4

6 0

6 6

7 2

7 8

8 4

9 0

9 6

1 0 2

T a n k A s p h a lt a n d R e c o v e r e d A s p h a lt

P G H ig h T e m p

P G G ra d e , T a n k S a m p le s

PG

Hig

h

Te

mp

(o

C)

T a n k A s p h a lt

R e c o v e r e d P la n t M ix

y = xR² = 1

y = 1.2027x - 7.6234R² = 0.5761

52

58

64

70

76

82

88

94

52 58 64 70 76 82 88 94

PG

Hig

h T

em

p (

Re

cove

red

)

PG High Temp (Tank)

PG High Temperature (Tank vs Recovered Asphalt)

y = xR² = 1

y = 1.2027x - 7.6234R² = 0.5761

52

58

64

70

76

82

88

94

52 58 64 70 76 82 88 94

PG

Hig

h T

em

p (

Re

cove

red

)

PG High Temp (Tank)

PG High Temperature (Tank vs Recovered Asphalt)

• HMA with 15% RAP

Standard Deviation

Tank = 0.3 to 2.4


5 8 -3 4

0 R

5 8 -3 4

0 R

5 8 -3 4

1 5 R

5 8 -2 8

0 R

6 4 -2 8

0 R

7 0 -2 8

0 R

7 0 -2 8

1 5 R

-4 6

-4 0

-3 4

-2 8

-2 2

-1 6

-1 0


P G L o w T e m p

P G G ra d e , T a n k S a m p le s

PG

Lo

w T

em

po

C


R e c o v e r e d P la n t M ix

y = xR² = 1y = 0.3517x - 20.693

R² = 0.0075

-46

-40

-34

-28

-22

-16

-10

-46 -40 -34 -28 -22 -16 -10

PG

Lo

w T

em

p (

Re

cove

red

)

PG Low Temp (Tank)

PG Low Temperature (Tank vs Recovered Asphalt)

y = xR² = 1y = 0.3517x - 20.693

R² = 0.0075

-46

-40

-34

-28

-22

-16

-10

-46 -40 -34 -28 -22 -16 -10

PG

Lo

w T

em

p (

Re

cove

red

)

PG Low Temp (Tank)

PG Low Temperature (Tank vs Recovered Asphalt)


Standard Deviation

Tank = 0.04 to 0.17


5 8 -3 4

0 R

5 8 -3 4

0 R

5 8 -3 4

1 5 R

5 8 -2 8

0 R

6 4 -2 8

0 R

7 0 -2 8

0 R

7 0 -2 8

1 5 R

0 .0 1

0 .1

1

1 0

T a n k A s p h a lt a n d R e c o v e r e d A s p h la t

N o n r e c o v e r a b le C o m p la in c e

P G G ra d e s a n d R A P C o n te n t

No

n

Re

co

ve

rab

le

Co

mp

(J

nr

3.2

)

(kP

a-1

)


R e c o v e r e d A s p h a lt

y = xR² = 1

y = 2.2203x - 0.3535R² = 0.5895

0

0.5

1

1.5

2

0 0.5 1 1.5 2

Jnr

3.2

kPa-

1 (

Re

cove

red

)

Jnr 3.2kPa-1 (Tank)

Non Recoverable Compliance(Tank vs Recovered Asphalt)

y = xR² = 1

y = 2.2203x - 0.3535R² = 0.5895

0

0.5

1

1.5

2

0 0.5 1 1.5 2

Jnr

3.2

kPa-

1 (

Re

cove

red

)

Jnr 3.2kPa-1 (Tank)

Non Recoverable Compliance(Tank vs Recovered Asphalt)


Ash Content

• Test established in Ontario to determine inorganic content in asphalt cement

• Implemented by MTO “to prevent over-modification of AC with Re-Refined/Recycled Engine Oil Bottoms (REOB).”1

• What about inorganic aggregate fines in recovered asphalt from plant produced mix?

1Modi et al. Innovative Testing of Ontario’s Asphalt Materials. CTAA 201623

Standard Deviation

Tank = 0.02 to 0.14


5 8 -3 4

0 R

8 -1 0 3 1

5 8 -3 4

0 R

4 -1 0 0 3

5 8 -3 4

1 5 R

3 -0 9 1 5

5 8 -2 8

0 R

6 -1 0 0 6

6 4 -2 8

0 R

7 -1 0 1 0

7 0 -2 8

0 R

1 -0 7 0 8

7 0 -2 8

1 5 R

2 -0 8 0 9

0

2

4

6

8

1 0


A s h C o n t e n t

P G G ra d e s a n d R A P C o n te n t

As

h

Co

nte

nt

(%)


R e c o v e r e d A s p h a lt

- - S p e c if ic a t io n 0 .6

25

y = -1.6882x + 3.379R² = 0.0285

y = xR² = 1

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6 7 8

Ash

Co

nte

nt

(Re

cove

red

)

Ash Content (Tank)

Ash Content (Tank vs Recovered Asphalt)



0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

Procedure-Solvent

G*/s

in δ

at

64 C

, k

Pa

Centrifuge

Abson

TCE

Centrifuge

Rotovapor

Toluene

SHRP

Rotovapor

TCE

SHRP

Rotovapor

Toluene

Kentucky RAP

26

The removal of mineral fines during the recovery procedure is critical to obtaining valid test results.

SHRP rotavapor procedure has a cartridge filter that helps remove more fine aggregate from effluent.

Research Objectives



27

Review: Asphalt Cement Properties

Asphalt is composed of extremely large number of organic molecules

Can be grouped into various molecular types and fractions:

• Saturates; Aromatics; Resins; Asphaltenes

Reacts with oxygen from environment

Oxidation/aging process changes the concentrations of these fractions

Aging Index

Absorbance AI =Toluene Soluble Asphaltenes

Resins

Aging index calculated using data from SAR-AD® on asphalt binders collected after various stages of aging in lab and field:

• RTFO lab aged binder

• 20hr PAV lab aged binder

• 40hr PAV lab aged binder

• Plant Mix (Recovered binder from mix that is field short term aged)

Lab aging getting close to field aging as difference approaches zero.

Aging Index of asphalt recovered from mix sampled from job site (field short term aged) is higher, or more oxidized than original (unaged) binder.

Aging Index of asphalt recovered from mix sampled from job site (field short term aged) is higher, or more oxidized than asphalt binder that is aged with RTFO (lab short term aged).

Aging Index of asphalt recovered from mix sampled from job site (field short term aged) is similar to, or just as oxidized as asphalt binder that is aged with RTFO+20hr PAV (lab long term aged).

Aging Index of asphalt recovered from mix sampled from job site (field short term aged) is less than, or less oxidized than asphalt binder that is aged with RTFO+40hr PAV (lab extended aging).

Summary

• The choice of procedure and solvent can have an impact on the resulting physical properties of the recovered asphalt binder

• During recovery aggregate fines remains in the recovered asphalt that will affect the physical properties

35

Summary

• Standard deviation on recovered asphalt binder are greater than the same values measured on tank asphalt binder.

• Asphalt aging in the field is more sever than what is currently done with lab aging (ie. Plant produced asphalt is not equal to RTFO aged asphalt)

36

Recommendations

• SHRP rotavapor method for recovery uses lower temperature and higher vacuum which could help minimize hardening during the recovery process

• Cartridge filter in SHRP rotavapor toluene procedure may remove more fine aggregate from the effluent

• Toluene solvent has least interference with polymers in asphalt

• Investigate performance testing for accessing asphalt mix quality

37

38

Documents

Solvent Extraction-Recovery Procedures and their Effect on ... 2019_Final_rev04-29-19.pdfSolvent Extraction-Recovery Procedures and their Effect on Recovered Asphalt Properties Presenter(s):