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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
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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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