Characterization of EvothermCharacterization of EvothermWarm Mix BinderWarm Mix Binder

Koichi Takamura, Ph.D.

BASF CorporationCharlotte, NC USA

koichi.takamura@basf.com

22

Plant Mixing Temperature

Harder the asphalt, higherthe mixing temperature withHot Mix

Independent on the asphalthardiness with Evotherm

The thin water film actsas the lubricant, as thecurling stone slides onthe ice

100

110

120

130

140

150

160

170

58 64 70 76 82

PG grading

Pla

nt

Mix

ing

Te

mp

era

ture

,°C

Hot Mix

Evotherm

3

Emulsion based Warm Mix

Significant reduction in CO, NOx and SO2 emissionsfrom stack

McAsphalt Trial in Oct. 4-5, 2005

Plant ProductionAggregate Asphalt Compaction

Hot Mix 155oC 155

oC 145

oC

Warm Mix 125oC *95

oC 85

oC

* Emulsion temp.Av. Stack Gas Temperature

Hot Mix 162oC

Warm Mix 121oC

Fuel Oil ConsumptionLitres/Tonne

Hot Mix 11.4Warm Mix 5.2

0

20

40

60

80

CO2 x10, % CO, ppm NOx, ppm SO2, ppm

Emissions from Stack

Warm Mix Hot Mix

46%

63%

58%

81%

4

Emulsion based Warm Mix

CO Emission

0

20

40

60

80

100

120

8:40 8:50 9:00 9:10 9:20 9:30

Time, minute

Co

ncen

trati

on

,p

pm

Hot mix (10/04/2005)

Warm Mix(10/05/2005)

SO2 Emission

0

2

4

6

8

10

12

14

16

18

8:40 8:50 9:00 9:10 9:20 9:30

Time, minute

Co

ncen

trati

on

,p

pm

Hot mix (10/04/2005)

Warm Mix(10/05/2005)

NOx Emission

0

10

20

30

40

50

60

70

80

8:40 8:50 9:00 9:10 9:20 9:30

Time, minute

Co

ncen

trati

on

,p

pm

Hot mix (10/04/2005)

Warm Mix(10/05/2005)

Residue RecoveryProcedure for Warm MixAsphalt Emulsion

6

Temperature profile of emulsionbased Warm Mix

Recovery Procedure for Asphalt Emulsion Residue Need to represent the mixing and paving

conditions

Location Temp., °C

Mixing temperature 130Discharge temperature 100In hopper of paver 97Just behind the screed of paver 92

at edge of mat 87at center of mat 92

After pneumatic roller 73Pavement 4 hrs after lay down* 52

*25mm below the surface

77

Evotherm trial by McAsphalt

Base asphalt had apenetration of 124dmm at25°C, 5s.

Asphalt cement recoveredfrom field core samples

Recovered AC from HotMix asphalt = 81dmm(63% of original value)

Recovered AC fromWarm Mix asphalt =107dmm (86% of originalvalue)

Less heat aging ofasphalt cement at themix plant

40

60

80

100

120

Pe

ne

tra

tio

na

t2

5°C

,d

mm

Base

AC

Rec

'dAC

from

HM

A

Rec

'dAC

from

WM

A

63% of

original

86%

8

Residue recovery procedure

Dry the emulsion at 80°C for 20 hours

80g emulsion in a PAV pan (~ 50gresidue)

Maintain stable polymer network

Recovered residue = Equivalent ofRTFOT sample of the hot mix AC

RTFOT simulate heat oxidation of AC at thehot mix plant

SHRP and other bindercharacterizations of recoveredresidue

Emulsion Residuewith 3% SBR Latex

100m

99

Residue recovery procedure

The new procedure closely simulate heat hardening ofEvotherm warm AC as penetration values

40

60

80

100

120

Pen

etr

ati

on

at

25°C

,d

mm

Base AC Rec'd AC from

HMA

Rec'd AC from

WMA

Ramada trial

63% of

Base AC

86%

0

20

40

60

80

100

Pe

ne

trati

on

at

25°C

,d

mm

Base AC Base after

RTFOT

Rec'd WM

residue

Binder characterization

56% of

Base AC

89%

10

Residue recovery procedure

Asphalt binder becomes brittleupon oxidation in the field Reduce fatigue and cold fracture

resistance of pavement

PAV: Laboratory simulation ofoxidative aging of asphalt binder 100°C at 2.1MPa pressure for 20

hours

Stable polymer network even afterthe PAV-aging

Residue after PAV

100m

Recovered residue

Emulsion Residue with 3% SBR Latex

11

Before and After PAV (FTIR)

Polymer modification does not prevent asphalt oxidation

Unmodified

0

0.01

0.02

0.03

0.04

0.05

0.06

900100011001200130014001500160017001800

Wavenumber, cm-1

Ab

so

rpti

on

After PAV

R-SO-R'COOH

R-CO-R'

R-CHO

3% SBR polymer modified0

0.01

0.02

0.03

0.04

0.05

0.06

900100011001200130014001500160017001800

Wavenumber, cm-1

Ab

so

rpti

on

After PAV

BdR-SO-R'COOH

R-CO-R'

R-CHO

12

Oxidative Hardening (Base asphalt/Unmodified residue)

Base asphalt shows sharp increase in complex modulus, G*, after PAV

Less significant hardening with Evotherm warm mix

Base asphalt after RTFOT Evotherm warm mix after PAV

Base asphalt

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

-30 -15 0 15 30 45 60 75

Temperature, °C

Co

mp

lex

mo

du

lus

,M

Pa

After PAV

after

RTFOT

Neat asphalt

Unmodified Residue

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

-30 -15 0 15 30 45 60 75

Temperature, °C

Co

mp

lex

mo

du

lus,

MP

a

after PAV

Rec'd residue

Unmodified Residue

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

-30 -15 0 15 30 45 60 75

Temperature, °C

Co

mp

lex

mo

du

lus

,M

Pa

Base asphalt

after RTFOT

Rec'd residue

after PAV

13

Before and After PAV (Physics)

Modification with SBR latex-polymer reduces negativeeffects of hardened asphalt at wide temperature range

Unmodified residue

0.0001

0.001

0.01

0.1

1

10

100

1000

-30 -15 0 15 30 45 60 75 90

Temperature, °C

Co

mp

lex

Mo

du

lus

[G*]

,M

Pa

After PAV

Before PAV

Oxidative hardening

(a) SBR latex modified

0.0001

0.001

0.01

0.1

1

10

100

1000

-30 -15 0 15 30 45 60 75 90

Temperature, °C

Co

mp

lex

Mo

du

lus

[G*]

,M

Pa

After PAV

Before PAV

(b)

0.4 Hz

14

Before and After PAV

7°C reduction in Tg with 3% SBR latex polymer

5°C increase in Tg after PAV, both unmodified and modified residues

Unmodified

10

100

-30 -25 -20 -15 -10 -5 0 5

Temperature, °C

Lo

ss

Mo

ulu

s(G

"),

MP

a

Tg=-16°C Tg=-11°C

After

PAV

(a) 3% SBR Latex

10

100

-30 -25 -20 -15 -10 -5 0 5

Temperature, °C

Lo

ss

Mo

du

lus

(G")

,M

Pa

After PAV

Tg=-23°C

Tg=-18°C

(b)

0.4 Hz

15

Cold Fracture Resistance: Stiffness with BBR

Improved Cold Fracture Resistance with Evotherm warm mix

Base asphalt after RTFOT Evotherm warm mix after PAV

100

1000

1 10 100 1000

Time, s

Cre

ep

Sti

ffin

ess,

MP

a

-18°C

Base Asphalt after

PAV: m-value = 0.31

Base Asphalt after

RTFOT: m-value = 0.38

Rec'd Residue after PAV:

m-value = 0.35

16

Bending Beam Rheometer

All binder samples are afterthe PAV-aging

Even unmodified residue islower creep stiffness than thebase asphalt used to makethe emulsion

SBR latex polymer furtherreduce the stiffness, thusmaintain low temp. flexibility100

1000

1 10 100 1000

Time, s

Cre

ep

Sti

ffn

es

s,

MP

a

Unmodified

residue

3% SBR

modified

residue

-18°C

Base Asphalt

1717

Fatigue Resistance under Repeated StressesUnmodified Binders

Base asphalt after RTFOT Evotherm warm mix after PAV

Unmodified Residue

0.01

0.1

1

10

100

0 30 60 90 120

Cumulative time, minutes

Co

mp

lex

mo

du

lus

,M

Pa

10%strain

5%strain

1%strain

0.1% strain

Unmod. Res., after PAV

0.01

0.1

1

10

100

0 30 60 90 120

Cumulative time, minutes

Co

mp

lex

mo

du

lus,

MP

a

7°C

Base AC, after RTFOT

0.01

0.1

1

10

100

0 30 60 90 120

Cumulative time, minutes

Co

mp

lex

mo

du

lus,

MP

a

1% strain

5%strain

10%strain

0.1% strain

1818

SBR Polymer Modified Residue

Evotherm with 3.0% SBR latex maintains excellent fatigue resistance

even after PAV --- Extended service life with >2% latex

1.5% SBR, After PAV

0.01

0.1

1

10

100

0 30 60 90 120

Cumulative time, min.

Co

mp

lex

mo

du

lus,M

Pa

1% strain

5% strain

10%

strain

1.5% SBR modified

0.01

0.1

1

10

100

0 30 60 90 120

Cumulative time, min.

Co

mp

lex

mo

du

lus,

MP

a

3.0% SBR, After PAV

0.001

0.01

0.1

1

10

100

0 30 60 90 120 150 180

Cumulative time, min.

Co

mp

lex

mo

du

lus,

MP

a

7°C

20%strain

19

Pavement Longevity

4, 20, 44 and 94 hours PAV-aging

FTIR for Chemistry

DSR for rheological measurements

– Binder samples were too brittle to do theBBR measurements after 44 hrs PAV-aging

20

Accelerated oxidative aging test (PAV)

SBR polymers remain even after 94 hrs PAV

McAsphalt PG58-28, 3% SBR Latex Modified Residue

0

0.1

0.2

0.3

900100011001200130014001500160017001800

Wave number, cm-1

Ab

so

rpti

on

6hr PAV

44hr

94hr

Butadiene

Neat asphalt

McAsphalt PG58-28, Unmodified Evotherm Residue

0

0.1

0.2

0.3

900100011001200130014001500160017001800

Wave number, cm-1

Ab

so

rpti

on

Neat asphalt

24 hr PAV

44 hr

94 hr R-SO-R'

R-COOH

R-CO-R'

R-CHO

2121

Accelerated oxidative aging test (PAV)

SBR polymers remain even after 94 hrs PAV-aging

McAsphalt PG58-28, 3% SBR Latex Modified Residue

0

0.1

0.2

0.3

900100011001200130014001500160017001800

Wave number, cm-1

Ab

so

rpti

on

6hr PAV

44hr

94hr

Butadiene

Neat asphalt

McAsphalt PG58-28, Unmodified Evotherm Residue

0

0.1

0.2

0.3

900100011001200130014001500160017001800

Wave number, cm-1

Ab

so

rpti

on

Neat asphalt

24 hr PAV

44 hr

94 hr R-SO-R'

R-COOH

R-CO-R'

R-CHO

50m

After 94hrs PAV-aging

22

Pavement Longevity: Ergon/Valero in Texas

Reduced Oxidative hardening of SBR latex modified residue.

0

3

6

9

12

1 10 100

Hours in PAV-aging

Co

mp

lex

Mo

du

lus

[G*]

at

25°C

,M

Pa

Base Asphalt

Unmod. Residue

3% SBR Mod. Residue

SHRP Procedure

25

35

45

55

65

1 10 100

Hours in PAV-aging

Ph

as

eA

ng

le,

deg

ree

Valero PG64-22

2323

Pavement Longevity: McAsphalt in Canada

Reduced Oxidative hardening of SBR latex modified residue,even after >20 years of service

25

35

45

55

65

1 10 100

Hours in PAV-aging

Ph

ase

an

gle

,d

eg

ree

McAsphalt PG58-280

5

10

15

20

1 10 100

Hours in PAV-aging

Co

mp

lex

Mo

du

lus

at

19

°C,

MP

a Base asphalt

Unmod. Residie

3% SBR Mod. Residue

24

Pavement Longevity: Shell China

Reduced Oxidative hardening of SBR latex modified residue

Consistent conclusion with 3 widely different asphalt

0

5

10

15

20

1 10 100

Hours in PAV-aging

Co

mp

lex

Mo

du

lus

at

13

°C,

MP

a

Base Asphalt

Unmodified Residue

3% SBR Mod. Residue

25

35

45

55

65

1 10 100

Hours in PAV-aging

Ph

ase

An

gle

at

13°C

,d

eg

ree

Shell China PG64*-22

25

Conclusions

Potential Pavement Longevity with WarmMix System Reduced oxidative hardening of asphalt binder during

the mixing and paving processes

D. Newcomb, the Vice President-Research & Technology,National Asphalt Pavement Association, states “Binder aging is directly related to the production temperature of the

mixture. The majority of binder hardening due to aging takes place inthe hot-mix plant. If the plant temperature is reduced, the oxidativehardening of the binder will be reduced. Less hardening of the binderduring construction could mean more flexibility and resistance tocracking in service. ---”

26

Reference

Davidson, J.K., Lubbers, C., Takamura, K., Proc.Canadian Technical Asphalt Assoc. 52, 297-324(2007)

Takamura, K., Road Materials and PavementDesign 9, 87-102 (2008)

2727