Design Consideration of Asphalt Mixtures Containing RAS ......Sam Cooper, Jr. Department of Civil...

Design Consideration of Asphalt Mixtures Containing RAS: Impact of Recycling Agents

Louay N. Mohammad Sam Cooper, Jr. Department of Civil and Environmental Engineering LA Transportation Research Center Louisiana State University

Asphalt Binder Expert Task Group

Baton Rouge, Louisiana September 16-17, 2014

William H. Daly Ioan Negulescu Sreelatha Balamurugan Department of Chemistry Louisiana State University

Presentation Outline • Background • Objective/Scope • Methodology

• Mix experiment • Binder Experiment

• Results • Summary/Conclusions

Sustainability in Flexible Pavement • Conventional materials

• Asphalt Treated Mixtures • Recycled materials

• RAP, CRM, RAS • Industrial waste extender

• Sulfur • Plant-based

• Bio-binder • Bio-rejuvenator

• Pavement construction practice • Warm Mix Asphalt

• Air-pollution reduction • photocatalytic pavements

Recycles Asphalt Shingles • Asphalt binder

– Post Consumer: 25 – 30% – Manufacture waste: 18 – 22%

• Mineral matter – 40 to 60% – granules and fillers

• Fibers – 8 to 12%

• Supply (US) • 10M: Post Consumer • 01M: Manufactures Waste

• Benefits • Sustainability • Partial aggregate and binder replacement • Prevent landfilling of valuable resource • Improved rut resistance

• Concerns • Consistency of asphalt content • Availability vs Credit of the asphalt binder • Quantity vs Quality of the asphalt binder • Performance

• Intermediate and low temperature

http://www.solidwasteagency.org/#/business/drop-off/shingle/

http://www.disastersafety.org/hail/shingle-roofs/attachment/asphalt-shingles/

Recycles Asphalt Shingles

Typical Asphalt Mixture Design • Volumetrics

– Voids in the Total Mix, VTM – Voids in the Mineral Aggregate, VMA – Voids Filled with Asphalt, VFA

• Densification – Stages during lab compaction

process

VOLUME MASS

air

asphalt

aggregate

Total Mass

Total Volume

aggregate

Use of RAS in HMA/WMA? • AASHTO MP 15-09 AASHTO MP 23-14

– Use of RAS as an Additive in Hot Mix Asphalt (Asphalt) • Provides Standard definitions for RAS • Process RAS

– 100% passing 12.5-mm sieve – Allows blending of RAS with fine aggregate

• Prevent agglomeration – Addresses deleterious materials

How to incorporate RAS in HMA/WMA? • AASHTO PP53 AASHTO PP 78-14

– Standard Practice for Design Considerations When Using RAS in Asphalt Mixtures

• Provides guidance on design considerations – RAS size can affect the fraction of RAS binder that contribute to the final

blended binder – fibers in RAS may require additional – virgin asphalt binder

• RAS asphalt availability factor is 0.70 - 1.0

Our Experiment • Design mixture with no shingles

– Calculate OAC • VMA, VTM

• Add shingles – Calculate OAC – VMA and VTM similar to mix with no shingles – Binder credit

• Add shingles + Recycling Agents – Calculate OAC – VMA and VTM similar to mix with no shingles – Binder credit

Objective / Scope – Mixture Experiment • Evaluate the intermediate and low temperatures laboratory performance

– conventional asphalt mixtures – mixtures containing RAS – Effect of recycling agents (RAs)

• Three 12.5mm Mixtures - RAs – Mix 4: 52PG5P-RA 1-B

• RAS = 5% PCWS • RA 1: PG 52-28

– Mix 5: 70PG5P-RA 2-B • RAS = 5% PCWS • RA 2 = 5%

– Mix 6: 70PG5P-RA 3-B • RAS = 5% PCWS • RA 3 = 12%

• Three 12.5mm Mixtures - NRA – Mix 1: 70CO

• RAS = 0% • PG 70-22M

– Mix 2: 70PG5M-B • RAS = 5% • Type: manufacturer waste

shingles (MWS) • PG 70-22M

– Mix 3: 70PG5P-B • RAS = 5% • Type: post-consumer

waste shingles (PCWS) • PG 70-22M

Objective / Scope – Binder Experiment

• Correlate the molecular structure of asphalt binders to fracture property of asphalt mixtures – Asphalt mixtures: Conventional – Asphalt mixtures: RAS with and without RAs

• Gel Permeation Chromatography (GPC) • Fourier Transform Infrared Spectroscopy (FTIR)

Design Consideration – OAC=5.3% No Recycling Agent

5.3

46% 100% 43% 100%

0.0

1.0

2.0

3.0

4.0

5.0

6.0

70CO (No RAS)Mix 1

Asph

alt B

inde

r Con

tent

, %

Mixture Type

RAS Binder Virgin Binder

Available RAS Binder = 26 * 5% RAS = 1.3

5.3

46% 100% 43% 100%

0.0

1.0

2.0

3.0

4.0

5.0

6.0

70CO (No RAS)Mix 1

70PG5M-BMix 2

70PG5M-AMix 2

Asph

alt B

inde

r Con

tent

, %

Mixture Type

RAS BinderVirgin Binder

4.7

Available MWS RAS Binder = 26 * 0.05 = 1.3 Available Binder Factor = (0.6/1.3)*100 ≈ 46%

0.6

4.0

1.3

Design Consideration – OAC=5.3% No Recycling Agent

5.3

5.3

46% 100% 36%

0.0

1.0

2.0

3.0

4.0

5.0

6.0

70CO (No RAS)Mix 1

70PG5M-BMix 2

70PG5M-AMix 2

70PG5P-BMix 3

70PG5P-AMix 3

Asph

alt B

inde

r Con

tent

, %

Mixture Type

RAS Binder Virgin Binder

4.7

100%

0.6 1.3

4.0

1.4 0.5

3.9

4.8

Available PCWS RAS Binder = 28% * 0.05 = 1.4% Available Binder Factor = (0.5/1.4)*100 ≈ 36%

Design Consideration – OAC=5.3% No Recycling Agent Virgin Binder ~ 90%

Mixture Design Concerns • Recycled binder Ratio (RBR) Recycled binder content / total binder content

• Design binder content – Mix with No RAS 5.3% binder

• Scenario 1 (100% availability -- P) RBR = 1.40 / 5.3 = 0.26

• Scenario 2 (< 100% availability -- P) RBR = 0.50 / 5.3 = 0.09

• Increase the RBR Recycling Agents

• Softening • Rejuvenators

• RBR = 0.30 – 0.50 Ensuring structural performance + volumetrics

• high temperature • intermediate temperature • low temperature performance • moisture damage resistance

RAS Type

%RAS Total AC Content

%RAS in Mix Design

%RAS AC Binder

Available PCWS 28.6 5.0 1.4

Mixture Design Concerns • Classes of Recycling Agents

• Purpose of Recycling Agents – Softening Agents

• lower the viscosity of the aged binder

– Rejuvenators • help restore physical and chemical properties of aged binder • contain a high proportion of maltene constituents

RAS Type


%RAS in Mix Design

%RAS AC Binder


REJUVENATING AGENTS SOFTENING AGENTS

Lube Extracts Lube Stock

Extender Oils (aromatic oils) Lubricating or Crankcase Oil Anti-Stripping Agent Slurry Oil

Naphthenic Oil Asphalt Flux Oils

Vegetable Derived Oils Soft Asphalt Binders

Mixture Design Concerns • Classes of Recycling Agents

• Purpose of Recycling Agents – Softening Agents

• lower the viscosity of the aged binder

– Rejuvenators • help restore physical and chemical properties of aged binder • contain a high proportion of maltene constituents

RAS Type


%RAS in Mix Design

%RAS AC Binder


REJUVENATING AGENTS SOFTENING AGENTS

Lube Extracts Lube Stock

Extender Oils (aromatic oils) Lubricating or Crankcase Oil Anti-Stripping Agent Slurry Oil

Naphthenic Oil – RA 3 Asphalt Flux Oils

Vegetable Derived Oils – RA 2 Soft Asphalt Binders -- RA 1

5.3

0.0

1.0

2.0

3.0

4.0

5.0

6.0

70CO (No RAS)Mix 1

Asph

alt B

inde

r Con

tent

, %

Mixture Type

Available RAS Binder = 28 * 5% RAS = 1.4%

0.5

Design Consideration – OAC=5.3% Recycling Agent (RA)

5.3

50% 100%

0.0

1.0

2.0

3.0

4.0

5.0

6.0

70CO (No RAS)Mix 1

52PG5P-RA 1-BMix 4

52PG5P-RA 1-AMix 4

Asph

alt B

inde

r Con

tent

, %

Mixture Type RAS Binder Virgin Binder

4.6 0.5

Available PCWS RAS Binder = 28 * 0.05 = 1.4 Available Binder Factor = (1.4/1.4)*100 = 100%

0.7

3.9

1.4

Design Consideration – OAC=5.3% Recycling Agent

RA 1

5.3

50% 100% 100%

0.0

1.0

2.0

3.0

4.0

5.0

6.0

70CO (No RAS)Mix 1

52PG5P-RA 1-BMix 4

52PG5P-RA 1-AMix 4

70PG5P-RA 2-BMix 5

70PG5P-RA 2-AMix 5

Asph

alt B

inde

r Con

tent

, %

Mixture Type

4.6

100%

0.7 1.4

3.9

1.4 1.4

3.9 3.9



RA 1 RA 2

5.3

50% 100% 100% 86% 100%

0.0

1.0

2.0

3.0

4.0

5.0

6.0

70CO (No RAS)Mix 1

52PG5P-RA 1-BMix 4

52PG5P-RA 1-AMix 4

70PG5P-RA 2-BMix 5

70PG5P-RA 2-AMix 5

70PG5P-RA 3-BMix 6

70PG5P-RA 3-AMix 6

Asph

alt B

inde

r Con

tent

, %

Mixture Type

4.6

100%

1.2 1.4

RA 3

3.9 4.1

0.7

1.4

3.9

1.4 1.4

3.9 3.9



RA 1 RA 2

Virgin Binder: 87%, 74%, 77%

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.09 0.11

0.13

0.26

0.23 Re

cycl

e Bi

nder

Rat

io

Mixture type

Recycled Binder Ratio

No Recycling Agents Recycling Agents

Laboratory Performance Tests Quality vs Quantity • Intermediate temperature Performance

– semi-circular bending test • Low temperature performance

– Thermal Stress Restrained Specimen Test

• Triplicates – VTM: 7 ± 0.5%

l Fracture mechanics– used for evaluating fracture resistance in rock mechanics

l Temperature: 25°Cl Half-circular Specimen

– Laboratory prepared– Field core– 150mm diameter X 57mm thickness– simply-supported and loaded at mid-point

l Notch controls path of crack propagation – 25.4-, 31.8-, and 38.0-mm

l Loading type– Monotonic– 0.5 mm/min – To failure

l Aging: 5 days, 85°Cl Record Load and Vertical Deformationl Compute Critical Strain Energy: Jc

Semi Circular Bend (SCB) Test

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0.0 0.5 1.0 1.5 2.0 2.5

Load

(kN

)

Deflection (mm)

Peak Load

notch a1

U1

Thermal Stress Restrained Specimen Test • AASHTO TP10-93 • Apply thermal loading

– -10 ± 1 °C per hour until specimen fracture • Continuously record

– Load, displacement, temperature • Determine the low-temperature cracking

susceptibility of asphalt concrete – Determine temperature and tensile strength at

fracture

http://www.cooper.co.uk/info/index.asp?page=asphalt_pavement_thermal_testing_system_307

Results

0.00

0.10

0.20

0.30

0.40

0.50

0.60

Jc, K

J/m

2

Mixture type

Virgin AC = 4.7-4.8% RAS AC = 0.5 – 0.6%

Semi-Circular Bend Test Results, 25°C

No Recycling Agents

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Jc, K

J/m

2

Mixture type

Virgin AC = 4.7-4.8% RAS AC = 0.5 – 0.6%

Virgin AC = 4.6 RAS AC = 0.7%

Virgin AC = 3.9% RAS AC = 1.4 – 1.2

Recycling Agents

Semi-Circular Bend Test Results, 25°C

No Recycling Agents

-50.0

-45.0

-40.0

-35.0

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

Frac

ture

Tem

pera

ture

, °C

Mixture type

Virgin AC = 4.7-4.8% RAS AC = 0.5 – 0.6%

Virgin AC = 4.6 RAS AC = 0.7%

Virgin AC = 3.9% RAS AC = 1.4 – 1.2

Recycling Agents

Thermal Stress Restrained Specimen Test

No Recycling Agents

Binder Experiment: Investigation of the Impact of Recycling Agent • Concern with mixture performance

– NRA vs RA • Chemical analysis

– Gel Permeation Chromatography, FTIR • Binder extracted from aged HMA mixtures

– 5 days, 85°C

Oxidation of Asphalt Matrix

Dispersed asphaltenes

COOH

HOOC

COOH

Asphaltene aggregation

Oxidative agingPolar groups stabilize aggregation

Polar groups may enhance adhesion to binder

Asphalt aggregates reinforce matrix

Typical GPC Chromatogram

34

Asphalt Characterization Utilizing Gel Permeation Chromatography (GPC) William Daly, Ionela Glover, Ioan Negulescu, Christopher Abadie, Louay Mohammad,Rafael Cueto

0

10

20

30

40

50

60

70. 0% MW 870

7.5% MW 3,200

21.5 % MW 8,600

∆RI (R

elativ

e Unit

s)

MW (Daltons x 10-3)

1.0% POLYMER MW 50,000

ASPHALTENESMALTENES

PG 70-22M

0.20.51251020501001000

0.211001000 50 20 10 5 2 0.5

Jc = 0.5 kJ/m2

MW distribution of molecular species of extracted binder: HMA mixture containing 0% RAS and PG70-22M binder

10 12 14 16 18 20 22 24

0

10

20

30

40

50

MW < 3000

MW 2000-300

MW 50K-3K200-50K

MaltenesMW zone

AssociatedAsphaltenesMW zone

∆RI (

Rela

tive

Units

)

TIME (min)

PMAC PG 76-22 RAS P

RAS P

PMAC

PolymerMW zone

Low-end MW Asphaltenes

1000000 100000 10000 1000

∆RI (

rela

tive

Units

)

Molecular weight (MW, dalton)

RAS M RAP

RAP

RAS M

MW 30,000MW 110,000

Associated Asphaltenes Maltenes

Typical MW Distributions of PMAC’s Modified with RAS

RAS M contributes higher conc. of associated asphaltenes with very high molecular weights than RAP

Associated asphaltenes overlap polymer molecular weights

GPC data of Air Blown shingle coating asphalt and MWS (RAS M) extracted binders

0

5

10

15

20

BLOWN ASPHALT

∆RI (

Rela

tive

Units

)

MW (Daltons x 10-3)

53K1.15%

28K6.5%

14K17.5%

3K45.0%

0.8K29.85%

MWS

0.20.51251020501001000

0.211001000 50 20 10 5 2 0.5

Binder of RAS M is practically identical to blown asphalt

MW distribution of molecular species of extracted binder: HMA mixture containing 5% RAS-M and PG70-22M binder

0

10

20

30

70PG5M

66.0 % MW 940

31.0% MW 6,400

3.0 % MW 24,000∆R

I (Rela

tive U

nits)

MW (Daltons x 10-3)

ASPHALTENES

MALTENES

0.20.51251020501001000

0.211001000 50 20 10 5 2 0.5

Jc = 0.5 kJ/m2

0

10

20

30

40

50

60

70

80

70PG5P 61.0 % MW 930

5.7 % MW 33,000

21.0% MW 4,300 12.6 %

MW 12,000

∆RI (

Relat

ive U

nits)

MW (Daltons x 10-3)

ASPHALTENES

MALTENES

0.20.51251020501001000

0.211001000 50 20 10 5 2 0.5

Jc = 0.5 kJ/m2

MW distribution of molecular species of extracted binder: HMA mixture containing 5% RAS-P and PG70-22M binder

0

10

20

30

40

50

60

70

80

1.50% RAS-P Asphaltenes?

76PG5P

∆RI (

Rela

tive

Units

)

MW (Daltons x 10-3)

MALTENES

0.50% SBR ASPHALTENES

36%MW 5,140

62%MW 900

0.20.51251020501001000

0.211001000 50 20 10 5 2 0.5

Jc = 0.7 kJ/m2

MW distribution of molecular species of extracted binder: HMA mixture containing 5% RAS-P and PG76-22M binder

Highest molecular weight component only 1,500 daltons

17 18 19 20 21 22

0

40

80

120

160

35.4% MW <200

39.0% MW 400

13.3% MW 1,500 12.3%

MW 1,040

∆RI (

Rela

tive

Units

)

TIME(min)

GREEN REJUVENATOR

MW distribution of molecular species: Recycling Agent 2 – RA 2

Impact of Recycling Agent 2

1k10k100k

1k10k100k

0.0

50.0k

100.0k

150.0k

200.0k

250.0k

∆RI

(Rel

ative

Uni

ts)

MW (Daltons)

70PG5PNHG SCB AGED 70PG5P5HG SCB AGED

MW 1100With HG

MW 850

NHG

70PG5P RA-2

70PG5P NRA-2

Jc = 0.2 kJ/m2 Jc = 0.4 kJ/m2

RAS = 5% PCWS RA 2 = 5% PG 70-22M

RAS = 5% PCWS No RA PG 70-22M

1001k10k100k1M

1001k10k100k1M

MW 850Aged

∆RI (

Relat

ive U

nits)

MW (Daltons)

70PG5P12CYCLO NOT AGED 70PG5P12CYCLO SCB AGED

MW 1090Not Aged

MW 26,000

Jc-aged = 0.3 kJ/m2 Jc-unaged = 0.3 kJ/m2

Impact of Recycling Agent 3

RAS = 5% PCWS RA 3 = 12% PG 70-22M

=

4000 3500 3000 2500 2000 1500 1000 500

}

r(C

ν CH aro

ν S=O

ν CH3

δasCH2,CH3

ν C=CνasCH3X, CH3 aryl

νaCH

νsCH2,CH3

νasCH2,CH3

C=O

Wavenumber cm-1

Abso

rban

ce

FTIR spectra of the aged samples show a peak around 1700 cm-1, characteristic of C=O species. The carbonyl index was calculated from the band areas measured from valley to valley as shown above*: Area of the carbonyl centered around 1700 cm-1 Carbonyl index = Σ Area of the spectral bands between 3500 and 500 cm-1

*J. Lamontagne et al., FUEL, 80(4), 483-48 (2001)

Wavenumber, cm-1

Estimation of Extent of Aging by FTIR

Mixture Type

Total VHMW % Polymer & Highly

Associated Asphaltenes >20K

C=O Index x103

Jc

KJ/m2

70CO 1.0 6.8 0.5

76CO 1.3 10.2 0.6

70PG5P 5.7 21.2 0.5

52PG5P-RA 1-B 5.7 11.7 0.2

70PG5P-RA 2-B 11.5 17.1 0.2

70PG5P-RA 3-B 8.8 13.0 0.3

Correlation of VHMW, Carbonyl Index , and Jc

Summary / Conclusions • Laboratory performance evaluation of asphalt mixtures

containing RAS – Design / Durability

• Design of Asphalt Mixtures – Availability of binder from RAS – AASHTO PP78 over-estimates the actual shingle asphalt

binder availability factor • 36% - 46% -- W/O RA • 86% - 100% -- RAs

• Volumetric-based design – Not sufficient

• Compliment with mechanistic tests – Performance related – Criteria

• Intermediate Temperature (SCB) – No adverse effects Mixes 1 – 3 (NRAs) – Lower Jc values Mixes 4 – 6 (RAs)

Summary / Conclusions • Effect of Recycling Agents

– Use of soft binder (RA 1) did not improve fracture properties. – RA 3 performed better than RA 2 at intermediate temp. – RA 2 enhanced the extraction of the asphaltenes from the

RAS. – Molecular fractionation through GPC of RAS samples

confirmed the presence of associated asphaltenes in great concentrations.

• High concentrations of HMW asphaltenes decrease the fracture resistance of the asphalt mixtures

• Presence of SBS additives enhances the compatibility with the HMW asphaltenes.

– C=O is not reliable indicator of intermediate fracture resistance performance.

– Use of RAs evaluated in this study did not reduce the concentration of the highly associated asphaltenes

• Did not improve the cracking resistance

Thoughts! • Is 100% blending of available RAS

binder desired? • Consideration of Addition of

additives that enhances the compatibility with the HMW asphaltenes

T H A N K

Y O U

Design Consideration of Asphalt Mixtures Containing RAS ......Sam Cooper, Jr. Department of Civil...

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Transcript of Design Consideration of Asphalt Mixtures Containing RAS ......Sam Cooper, Jr. Department of Civil...