Introducing High Modulus Asphalt (HiMA) · Introducing High Modulus Asphalt (HiMA) Prepared for...

Introducing High Modulus Asphalt(HiMA)

Prepared for presentation at the JD Roberts Award functionCSIR Pretoria, 27 September 2011 CSIR Pretoria, 27 September 2011

Erik Denneman

1

� The need for innovative asphalt technology,

� Background to the HiMA T2 project,

� Benefits of HiMA technology,

� Designing for performance,

� Implementation of the technology,

� Way forward,

Outline of presentation2-27

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� Way forward,

� Conclusions.

© CSIR 2011

The need for innovation3-27

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- Economic growth,Economic growth,

-- Higher traffic volumes,Higher traffic volumes,

-- Higher axle loads,Higher axle loads,

-- Higher tyre pressures,Higher tyre pressures,

-- Need for sustainable use of resources,Need for sustainable use of resources,

-- Design concepts from 1950s still suitable?Design concepts from 1950s still suitable?

Background: What is High Modulus Asphalt ?4-27

Origin: France early 90s

“Enrobés à Module Elevé” (EME)

Typical characteristics:

• High binder content ≈ 6% by mass of aggregate,

• Hard binder: Pen 10-25,

• Low air voids content,

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• Low air voids content,

• High Modulus > 14 GPa at 15°C, 10 Hz,

• High resistance against permanent deformation,

• Good fatigue resistance,

• Impermeable,

• Increased mixing temperature.

Background: The greater scheme of things5-27

SAPDM

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SA asphalt design manual

HiMAT2

Background: Structure of SABITA T2 project6-27

Phase IIPreliminary mix and structural design guidelines

Phase IFeasibility study

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Phase IVFinal guidelines and specifications

Phase IIIImplementation: APT,LTPP and lab study

Background: The properties of HiMA7-27

1000

10000

100000

Dy

na

mic

Mo

du

lus

(M

Pa

)

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1

10

100

0.00001 0.001 0.1 10 1000 100000

Dy

na

mic

Mo

du

lus

(M

Pa

)

Reduced frequency (Hz)

BTB Mix

Coarse/SBS

Medium/SBS

HiMA

Background: The properties of HiMA8-27

2.5%

3.0%

3.5%

4.0%

4.5%

5.0%

Pe

rma

ne

nt

stra

in [

%]

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0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

0 5 000 10 000 15 000 20 000 25 000 30 000

Pe

rma

ne

nt

stra

in [

%]

Load repetitions

BTB 1 55°C Coarse AE2 55°C Medium AE2 55°C

HiMA 55°C Medium 60/70 55°C BRASO 55°C

Rutting9-27

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Background: The properties of HiMA10-27

1000

10000

ST

RA

IN (M

icro

str

ain

)

Strain-fatigue relationship at test temperatures at 70% initial stiffness reduction

Mix 1 (BTB)

Mix 3

Mix 4 (HiMA)

All at 10 Degrees C

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10

100

1000 10000 100000 1000000 10000000 100000000

ST

RA

IN (M

icro

str

ain

)

Number of load cycles

Fatigue11-27

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The benefits of HiMA: Thickness reduction12-27

180mm BTB

450mm C3

50mm HMA

100mm HiMA

450mm C3

50mm HMA�

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450mm C3

Subgrade

� Average base layer thickness reduction of 30% �

450mm C3

Subgrade

The benefits of HiMA: Long life pavements13-27

180mm BTB

450mm C3

50mm HMA�

180mm HiMA

������

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450mm C3

Subgrade

� Less maintenance = less road user delays, less

emissions & less us of non-renewable materials �

Performance related mix design14-27

Select components

Formulate design grading

Select binder content

Compact gyratory specimens

Workability criteria met?

Yes

No

� First implementation of performance related mix design method in SA,

� Direct link between mix design and pavement performance,

� Requirements set for SA test methods:

� Workability,

Durability,

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Durability criteria met?

Dynamic modulus criteria met?

Compact slab

Rut resistance criteria met?

Fatigue criteria met?

Implement!

YesNo

Yes

Yes

Yes

Yes

No

No

No

� Durability,

� Stiffness,

� Rut resistance,

� Fatigue.

Implementation15-27

� Mix designs prepared for Cape Town international airport and OR Tambo

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� South coast road Durban

Implementation16-27

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Implementation17-27

� Road owned by eThekwini municipality,

� Major access road for DBN harbour,

� Frequent maintenance to pavements required (six months life span not uncommon),

� Road too busy to use concrete,

Estimated number of standard axels: 8000

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� Estimated number of standard axels: 8000 per lane per day (60 Million E80s in 20 years),

� CSIR tasked by SABITA to provide implementation advice.

Implementation18-27

� Mix Design:

� Interim design guide used to develop mix,

� Mix includes 20% Reclaimed Asphalt Pavement (RAP),

� 10-20 penetration grade binder,

Aggregate packing optimized,

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� Aggregate packing optimized,

� Several iterations to optimise design,

� Relatively low binder content to optimise permanent deformation resistance.

Implementation19-27

� Mix Design:

� Interim design guide used to develop mix,

� Mix includes 20% Reclaimed Asphalt Pavement (RAP),

� 10-20 penetration grade binder,

5.2% binder content selected to optimise

4.0%

5.0%

6.0%

7.0%

8.0%

Pe

rma

ne

nt

stra

in [

%]

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� 5.2% binder content selected to optimise permanent deformation resistance

0.0%

1.0%

2.0%

3.0%

0 1 000 2 000 3 000 4 000 5 000

Pe

rma

ne

nt

stra

in [

%]

Load repetitions

BTB 1 55°C Coarse AE2 55°C Medium AE2 55°C

HiMA reference Medium 60/70 55°C BRASO 55°C

Design 5.7 Design 5.2

Implementation20-27

� Innovations in the structural design process:

� CSIR Pavement temperature prediction software used,

� Use of new SAPDM models for rutting prediction,

� Use of new SAPDM approach to determine stiffness of HiMA at

Vertical plane parallel to Y-Z at X = 0

Shear Strain YZ

-0.000018

-0.000081

-0.000144

-0.000208

-0.000271

-0.000334

-0.000397

-0.000461

-0.000524

-0.000587

-0.000650

-0.000714

-0.000777

-0.000840

-0.000903

-0.000966

-0.001030

-0.001093

-0.001156

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determine stiffness of HiMA atcombination of loading speed and temperature,

� Preferred option: Two 80 mm HiMA layers, with 30 mm Stone Mastic Asphalt (SMA) surfacing,

� Predicted life of HiMA base layers >100 Million standard axels.

0

5000

10000

15000

20000

25000

30000

35000

-10 0 10 20 30 40 50 60

Mo

du

lus

(Mp

a)

Temperature (°C)

HiMA stiffness

-0.001156

Implementation21-27

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Implementation22-27

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Implementation23-27

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Implementation24-27

� Paving of HiMA layers South Coast road completed 6 September 2011,

� Many challenges overcome and lessons learned during construction,

� Performance of section over time to be monitored by CSIR.

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Way forward25-27

� HiMA mix designs developed for two major asphalt producers,

� The use of HiMA being investigated for various road construction projects,

� Laboratory trials with warm mixed HiMAunderway,

CSIR and Much Asphalt collaborate on

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� CSIR and Much Asphalt collaborate on innovative labour intensive HiMA application,

� The experience gained with performance related mix design will be used in the development of the South African Asphalt Mix Design Manual.

Conclusions

� HiMA technology successfully transferred,

� Performance related mix design guidelines available to industry,

� Benefits of HiMA:� Reduction in life cycle costs,� Improved durability,

� Reduction in road user delay costs,

Increased sustainability of pavement

26-27

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� Increased sustainability of pavement structure.

� Link between mix design and pavement performance made,

� HiMA set for large scale implementation,

� HiMA is a cost effective, innovative solution to help meet the increased demands placed on the SA road infrastructure.

Acknowledgements

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