use of rejuvenators (recycling agents) with …...shingles (ras) •workability •compaction...

Transportation Short CourseOctober 10, 2017

USE OF REJUVENATORS (RECYCLING AGENTS)

WITH RECYCLED MATERIALS

MOTIVATION

• Reclaimed Asphalt Pavement (RAP)

• Recycled Asphalt Shingles (RAS)

• Workability

• Compaction

• Performance(cracking, raveling)

College Station, TX Transportation Short Course October 10, 2017

HOW DO WE EXPRESS RAP AND RAS CONTENT?

• Traditionally, by % of total mix (10% RAP & 5% RAS)

• Recently, Recycled Binder Ratio or RBR (decimal)

𝑅𝐵𝑅 = 𝑅𝐴𝑃𝐵𝑅 + 𝑅𝐴𝑆𝐵𝑅 = 𝑃𝑏𝑅𝐴𝑃 × 𝑃𝑅𝐴𝑃

𝑃𝑏𝑡𝑜𝑡𝑎𝑙+

𝑃𝑏𝑅𝐴𝑆 × 𝑃𝑅𝐴𝑆𝑃𝑏𝑡𝑜𝑡𝑎𝑙

https://eng.auburn.edu/research/centers/ncat/info-pubs/newsletters/atnfall2014.pdf


TxDOT ITEMS 340, 341, 344

RECYCLED BINDER RATIO (RBR)

• Advantages:

– RAPB & RASBR

– Weighted average of multiple components

• Disadvantages:

– Assumes 100% blending

Proposed shorthand notation

A/B|D/E

– A = RAP % of total mix

– B = RAS % of total mix

– C = RAPBR (decimal)

– D = RASBR (decimal)


HOW CAN MORE RAP AND RAS BE USED IN SURFACE MIXTURES?

RAP

RAS

Rejuvenated

Blend

Rejuvenated

Mixture

Recycling

Agents

Virgin

Binder

Virgin

Aggregates


WHAT ARE RECYCLING AGENTS?

Chemical products added to recycled asphalt mixtures

– To reduce mixture stiffness(asphaltene to maltene ratio)

– To improve the low-temperature and high-temperature PG

– Other benefits: better workability, better compaction, etc.


WHAT TYPES OF RECYCLING AGENTS ARE AVAILABLE?


HOW TO SELECT A RECYCLING AGENT?

Chemistry (FT-IR) Rheology (DSR)

0

10

20

30

40

50

60

T1 T2 A1 V2 V1 B

S│

DA

rea│

(a.

u.)

RTFO PAV 20 PAV 40

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

T1 A1 V2 B

h*

at1

5ᵒC

an

d 1

0 r

ad/s

(Pa.

s)

Original RTFO PAV 20 PAV 40

RA with smallest D FT-IR registered minimal D in rheologyT1 w/ greatest D in rheology & among highest D FT-IR


HOW TO SELECT A RECYCLING AGENT?

RA with smallest D FT-IR registered minimal D in rheologyT1 w/ greatest D in rheology & among highest D FT-IR


HOW MUCH RECYCLING AGENT SHOULD I ADD TO THE MIXTURE?

• High-Temp PG (DSR)

– Unaged

– RTFO aged

• Low-Temp PG (BBR)

20-hour PAV aged

𝚫𝑻𝒄 = (𝑻𝑺 − 𝑻𝒎)


RECYCLING AGENT DOSAGE SELECTIONDETAILED METHOD

y = -1.8x + 81.8

y = -1.7x + 85.1

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12

Hig

h T

emp

. P

G G

rad

e (

C)

Dosage (%)

0.3 RBR (PG 64-22 | 0.1 TxRAP | 0.2 TxMWAS | T1)

Original G*/sin(d) RTFO G*/sin(d)

y = -1.8x + 81.8

y = -1.7x + 85.1

y = -1.3x - 16.0

y = -0.7x - 28.5

-40

-35

-30

-25

-20

-15

-10

-5

0

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12

Lo

w T

emp

. P

G G

ra

de ( C

)

Hig

h T

emp

. P

G G

rad

e (

C)

Dosage (%)

0.3 RBR (PG 64-22 | 0.1 TxRAP | 0.2 TxMWAS | T1)

Original G*/sin(d) RTFO G*/sin(d) PAV m-controlled PAV S-controlled

y = -1.8x + 81.8

y = -1.7x + 85.1

y = -1.3x - 16.0

y = -0.7x - 28.5

-40

-35

-30

-25

-20

-15

-10

-5

0

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12

Lo

w T

emp

. P

G G

rad

e (

C)

Hig

h T

emp

. P

G G

rad

e (

C)

Dosage (%)

0.28 RBR (Tx PG 64-22 | 0.1 TxRAP | 0.18 TxMWAS | T)


A (6.0,70)

Target Grade: 70-22

y = -1.8x + 81.8

y = -1.7x + 85.1

y = -1.3x - 16.0

y = -0.7x - 28.5

-40

-35

-30

-25

-20

-15

-10

-5

0

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12

Low

Tem

p. P

G G

rad

e (

C)

Hig

h T

emp

. P

G G

rad

e (

C)

Dosage (%)

0.28 RBR (Tx PG 64-22 | 0.1 TxRAP | 0.18 TxMWAS | T)


B (6.0,-23)

A (6.0,70)

Target Grade: 70-22

Blend Grade: 70-23

DTc = -9.0 C

Selected Dosage: 6.0%

RECYCLED BLENDS:

– Virgin binder +

– Recycled binder(extracted & recovered) +

a) No recycling agent

b) Low dosage(2% or 5%)

c) Higher dosage(~10%)


RECYCLING AGENT DOSAGE SELECTIONQUICK METHOD

• RECYCLED MATERIALS:

– Virgin binder

– Recycled binder(extracted & recovered)

• No recycled blends

• High-Temp PG only

• Unaged only

67.772.5

59.4

83.5

-44

-32

-20

-8

4

16

28

40

52

64

76

88

100

112

-44

-32

-20

-8

4

16

28

40

52

64

76

88

100

112

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

RA

P B

ind

er C

on

tin

uou

s P

G (⁰C

)

Vir

gin

Bin

der

Con

tin

uou

s P

G (⁰C

)

RBR

WI PG 58-28 + 0.31 WI RAP and WI PG 58-28 + 0.5 WI RAP

Measured Continuous PGH 0.31 RBR Measured Continuous PGH 0.5 RBR


RECYCLING AGENT DOSAGE SELECTIONQUICK METHOD


• Estimate the High-Temp PG of the blend

• Estimate the recycling agent dosage

𝑹𝒆𝒄𝒚𝒄𝒍𝒊𝒏𝒈 𝑨𝒈𝒆𝒏𝒕 (%) = 𝑷𝑮𝑯𝑩𝒍𝒆𝒏𝒅 − 𝑷𝑮𝑯𝑻𝒂𝒓𝒈𝒆𝒕 / 𝟏.𝟕𝟐

𝑹𝒆𝒄𝒚𝒄𝒍𝒊𝒏𝒈 𝑨𝒈𝒆𝒏𝒕 (%) = 𝑷𝑮𝑯𝑩𝒍𝒆𝒏𝒅 −𝑷𝑮𝑯𝑻𝒂𝒓𝒈𝒆𝒕 / 𝐬𝐥𝐨𝐩𝐞 𝐫𝐚𝐭𝐞

𝑷𝑮𝑯𝑩𝒍𝒆𝒏𝒅 = 𝑹𝑨𝑷𝑩𝑹 × 𝑷𝑮𝑯𝑹𝑨𝑷 + (𝑹𝑨𝑺𝑩𝑹 × 𝑷𝑮𝑯𝑹𝑨𝑺) + (𝑩𝑩𝑹 × 𝑷𝑮𝑯𝑩𝒂𝒔𝒆)

WHAT ABOUT BLENDING?

• Most DOTs assume 100% RAP/RAS binder blending

• In reality…

100% BlendingPerfect Blending

0% BlendingBlack Rock

PARTIAL BLENDING


WHAT FACTORS AFFECT BLENDING?

93.0%86.1%

67.5%

40.1%

0%

20%

40%

60%

80%

100%

RAP 1 RAP 2 RAP 3 RAP 4

Bin

der

Ble

nd

ing

RAP aging

4.27% 4.50%

5.11%

6.01%

2%

3%

4%

5%

6%

7%

8%


RA

P b

ind

er c

on

ten

t af

ter

mix

ing

wit

h v

irgi

n b

ind

er

Artificial RAP

0% Blending

100% Blending

40.8%

73.4%

43.7%

75.6%

53.0%

86.9%

0%

20%

40%

60%

80%

100%

TX RAP NH RAP

Bin

de

r B

len

din

g

RAPRAP+RA (added to the binder)RAP+RA (added to the RAP)

107.6 90.0High Temp PG

Stiffer RAP yielded lower binder

blending



93.0%86.1%

67.5%

40.1%

0%

20%

40%

60%

80%

100%


Bin

der

Ble

nd

ing

RAP aging

4.27% 4.50%

5.11%

6.01%

2%

3%

4%

5%

6%

7%

8%


RA

P b

ind

er c

on

ten

t af

ter

mix

ing

wit

h v

irgi

n b

ind

er

Artificial RAP

0% Blending

100% Blending

40.8%

73.4%

43.7%

75.6%

53.0%

86.9%

0%

20%

40%

60%

80%

100%

TX RAP NH RAP

Bin

de

r B

len

din

g



Marginal increase when the recycling agent was added to

the binder



93.0%86.1%

67.5%

40.1%

0%

20%

40%

60%

80%

100%


Bin

der

Ble

nd

ing

RAP aging

4.27% 4.50%

5.11%

6.01%

2%

3%

4%

5%

6%

7%

8%


RA

P b

ind

er c

on

ten

t af

ter

mix

ing

wit

h v

irgi

n b

ind

er

Artificial RAP

0% Blending

100% Blending

40.8%

73.4%

43.7%

75.6%

53.0%

86.9%

0%

20%

40%

60%

80%

100%

TX RAP NH RAP

Bin

de

r B

len

din

g



Higher blending when recycling

agent was added to the RAP


RAP CHARACTERISTICS

Source PGContinuous

High-Temp PG (°C)Continuous

Low-Temp PG (°C)ΔTc (°C)

Texas — 106.6 -2.4 -9.8

Indiana 88-10 90.4 -13.7 -6.2

Nevada 82-16 84.4 -20.4 -3.4

New Hampshire

88-16 90.2 -20.6 -2.1

Wisconsin 82-10 83.5 -10.9 -7.3

Delaware 82-10 86.2 -13.8 -4.4

TAKEAWAYS

• There is a push to increase the amount of recycled materials in asphalt mixtures.

• But, construction and performance issues still exist.

• It is possible to increase the amount of recycled materials by incorporating recycling agents.

• There are many recycling agents currently available and not a standard way of selecting the “right one”.


TAKEAWAYS

• There are ways of estimating the recycling agent dosage with minimal testing.

• Partial blending occurs between the recycled materials binder and the virgin binder in the mixture.

• Degree of blending depends on the characteristics of the recycled materials (aging) and how the recycling agent is added to the mixture.


THANK YOU!

Edith Arámbula Mercado(979) 458-0209

[email protected]

Amy Epps Martin(979) 862.1750

[email protected]

use of rejuvenators (recycling agents) with …...shingles (ras) •workability •compaction...

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