Use of Public Roads New perspectives in mixture designing Role of the state in Technological Developments

1
Use of Public Roads New perspectives in mixture
designingRole of the state in Technological
Developments

• Chantal de La ROCHE
• LCPC - France
• Head of Road and binders materials section

Performance-based Road Construction
Technology Terms of Reference, Contract,
Conditions Conference of Hungarian Road Society -
16-17 Nov 2005
2
Outlines

• French road networks some figures
• An example of performance based mix design
  methodology
• Trends in bituminous mixture evolution
• Role of the state in technological development
• Conclusion and future prospects.

3
Overview of the French Road Natwork
Superficies 550 000 km² Population 63
Millions 1 million kms of roads
Notional Roads 20 000 km Toll
Motorways 8 000 km Free motorways
3 000 km Routes de liaisons 8 800
km Departments 380 000 km Cities
600 000 km
4
French Roads some figures
Transfer to local authorities 1/1/2006 RN 12
000 kms
Average traffic 20 à 60 000 v/j
Temperate climate ? ? surface -15C, 60C,
average 15C
5
French Roads some figures
Remark legal axle load 130 kN
6
An example of performance based
methodologyFrench Bituminous Mix Design
Methodology
7
One material type for each needOptimized with
performance based criteriaIn relation with its
use on the road
Principle
8
Mix design and Composition

• Standard Performances
  Lab study
• Gradation Binder content
  designers choice

100
Formulation tool Gyratory Compactor (PCG)
90
ECF
80
BBSG
70
60
BBM
Paasing
50
BBTM
40
BBUM
30
BBDr
20
10
Sieve mm
0
0.1
1
10
Typical grading curves
9
Mix design Formulation method

• Components selection(aggregates, filler, binder,
  additives)
• Check of their properties
• performance class
• Minimum binder content defined by standard
• K Richness modulus (linked to the binder film
  thickness)
• Level of mix design study
• defined in contract
• Check of the performance versus the selected
  class of the product standard

10
Performances tested

• One test per property
• Gyratory compactor (PCG)
• workability and compactability assessment
• Immersion compression (Duriez) test
• Water sensitivity
• Wheel tracking test
• Rutting resistance
• Direct tensile or 2 point bending test
• Stiffness
• 2 points bending test
• Fatigue resistance

11
Design steps
Selection and identification of components
Choice gradation binder content
Compactability test (gyratory)
Compaction Water sensitivity
Level 1
Duriez test
Rutting test
Level 2
Rutting
Level 3
Stiffness
Modulus test
Fatigue test
Level 4
Fatigue
Formulation selected
12
Level 1 and 2 tests

• Components selection(aggregates, filler, binder,
  additives)
• Check of their properties
• performance class
• Manufacturing and control of samples
• Gyratory compaction test
• Water sensitivity
• Wheel tracking rutting test
• Marshall

13
Preparation of samples in laboratory

• Good control quality of mix composition,
  voids,..
• Homogeneity
• Accurate and Relevant Tests
• Relevant comparison with in situ materials

14
Plate compactor 400600150 or 18050025 à 100
Manufactoring voids
EN 12697-33 ex NFP 98-250-2
Mixer BBMAX 80
Vertical gamma Bench
EN 12697-35 ex NFP 98-250-1)
(EN 12697-7 ex NFP 98-250-5)
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Compactability characterisation

• Gyratory compactor
• Standard (NF 12697-31 ex NFP 98-252)
• Characterisation of void reduction under axial
  force gyratory shear
• Mix design by adjustment of void content
  according to product standards
• Estimation of site void content Vsite V(Ne)
• Ne nbr of cycle as thickness mm
• r 0,95 R 1,38 ( voids 60 g)

MLPC Gyratory shear compactor
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Typical result
Void content ()
Repetability 0,95 Reproducibility 1,34
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Interpretationof gyratory compaction test

• Conformity study of a mix in relation to product
  standard specification for each material type (
  NFP 98-130 to 141)

Void content
Pass
Failed
Failed
18
Void content versus layer thicknessIn site
compaction process
voids
12 cm
5
8
6
10
4
20
26
16
2
8
Number of passes
19
Gyratory compactor test specifications
20
Water sensitivity Duriez test

• Standard NFP 98-251-1
• Two compaction efforts
• Dlt 14 mm H 190 mm, 60 kN, 5 min
• Dgt14 mm H 270 mm, 180 kN, 5 min
• Stored at 18 C, 7 days
• in air (50 moisture)
• in water
• Vertical compression (1 mm/s )
• Ratio r/R (and voids)
• Repeatability and reproducibility
• r 0,08
• R 0,13 (ratio of 0,73)

? Decision to use of an adhesion agent ? European
standard indirect tensile test (EN 12697-12)
21
Level 2 rutting resistance test
22
LPC Wheel tracking test
23
LPC Wheel tracking test

• Standard (EN 12697-22 ex NFP 98-253-1
• Influence of heavy, slow, channelled traffic
  under high temperature
• relevant correlation with site, repeatability (r
  1,2 et R 1,3)
• Test conditions
• Smooth tire, pressure 0.6 MPa
• Load 5 kN, speed 1 cycle/s
• Controlled temperature 60C

24
Typical results with the LCPC wheel tracking
Rutting
Average
Regression
Number of cycles
25
Influence of binder content
26
Influence of binder type
27
Influence of sand nature
28
Influence of aggregates shape
29
Influence of void content
30
Rutting resistance -specifications

• Test _at_ 60 C

Base
Surface
20
Out of spec
16
12
Rut depth
8
On spec
4
0
BBA
BBA
BBA
BBME
BBME
BBME
GB 2
EME
1
2
3
1
2
3
to 4
1-2
Number of cycles
10 000
30 000
10 000
30 000
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Level 3 and 4

• Mechanical tests
• stiffness measurement (direct tensile test or 2
  points bending on trapezoidal samples)
• Fatigue resistance test

32
Determination of bituminous mixes mechanical
characteristics for pavement structural design
Need for stiffness characteristics and fatigue
resistance admissible strain for 1 million
cycles

33
Direct tensile test

• EN 12697-26 ex NFP 98 260-1
• Direct tension on cylindrical specimen
• Master curve (rheological behavior)
• Modulus for pavement design (specification)
  15C, 0,02s

34
Complex modulus test
r 335 MPa , R 2750 MPa (E 15300 MPa)

• EN 12697-26 ex NFP 98 260-2
• 2 points bending on trapezoidal samples, 4
  repetitions
• E pavement design 15C, 10 Hz
• Master curve (rheological behavior)

35
Stiffness

• Modulus _at_ 15C complex (10 Hz) or tensile (0,02
  s)

20000
18000
16000
On spec
14000
12000
Modulus MPa
10000
8000
6000
4000
Out of spec
2000
0
BBA
BBA
BBME
BBME
GB 2-
GB 4
EME
1-2
3
1
2-3
3
1-2
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Fatigue test

• Standard EN 12697-24 ex NF P 98-261-1
• 2 points Bending beam on trapezoidal samples
• B56, b25, t2, h250 mm
• 3 strain levels with 6 specimens each, 10C and
  25 Hz
• Strain calculated for 1 million of cycles ?6
• (better behavior for high ?6)
• r 4,2 µstrain R 8,3 µstrain

?6
37
Fatigue test

• Admissible strain _at_ 10 C and 25 Hz µstrain

150
140
130
On spec
e6 µstrain
120
110
100
90
Out of spec
80
70
BBA 1
BBA 2
BBA 3
BBME
BBME
GB 2
GB 3
GB 4
EME
EME
1
2-3
1
2
38
Summary of the French mix design methodology
Level 4
Fatigue
Level 3
Stiffness
Level 2
Permanent deformation
level1
Giratory, water sensitivity
39
Trends in bituminous mixtures evolutionsDissocia
tion of layer functions
base structure wearing course surface
caracteristics.
40
Base materials evolution

• Higher and higher binder contents
• Smaller aggregate maximum size
• 31 ? 20 ? 14 ? 10 mm
• Increase of bitumen hardness
• 50 ? 35 ? 20 ? 10 pen
• Additives to increase hardness
• Performances improvement
• GB 3 then GB 4
• EME 2
• Reduction of thicknesses

41
Base and foundation materials evolution
42
Base Hot Mix Asphalt main performances
43
surface materials evolution

• Thinner and thinner layers ? 1 to 2cm
• Gap graded curves
• ? Increase of porosity
• ? Need for water proofing tack coat
• More and more use of modified and special binders
• Standardized products ? performance
  characteristics

44
Role of the state in Technological Developments
45
Existing tools

• Common researches between French administration
  and road contractors
• ? development of products, methodologies,
  laboratory devices, techniques, technical guides
• Standardization
• French since 1992 ? 10 product standards
• European with typical French products such
  as BBTM taken into account
• Innovation policy of the French administration ?
  example innovation protocol (charte de
  linnovation)

46
Innovation policy

• For more than 25 years
• Strong input of French administration
• Innovative Techniques Concourse
• Technical advices (avis techniques)
• Innovation protocol (charte de linnovation)

47
Innovation policy - examples

• Innovation protocols
• (chartes de linnovation)
• French Road administration/road contractors
• French Road administration/toll motorway
  companies
• Technical conventions SETRA / Departments

48
Innovation protocol mean features

• Focus on some priority subjects
• Partnership
• Sharing of observation data
• Financial risk acceptation French Road
  administration pays for over cost and possible
  repairs
• Common conclusion
• Leading committee
• Technical validation Certificate

49
Innovation protocol Organisation
SUBJECTS PROPOSALS SELECTION
AGREMENT PROTOCOL
EXPERIMENTATIONS SURVEYS CONCLUSIONS -
DECISION CERTIFICATE
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Some studied subjects among the various
innovation protocols

• Preventing permanent deformation
• Preventing reflective cracking
• Bituminous mixtures recycling
• Improvement of surface characteristics
• Recycling porous asphalts
• Cleanliness of tack coats
• ..

51
Conclusion after 10 years (French Road
administration - road contractors)

• 79 agreement protocols
• 189 innovative sites
• 60 French departments
• All the French road contactors
• 24 certificates
• 10 Millions uros (over costs)
• Survey by the Regional Laboratories of Ponts et
  Chaussées

52
Conclusions

• French mix design methodology is based on the
  following performances
• Workability assessment (Giratory, central tool)
• Water sensitivity
• Resistance to permanent deformation
• Stiffness
• Fatigue
• depending on the mix design study level asked in
  contractual documents
• Performances based mix design methodology allows
• Optimization of mix design to the expected use of
  the material
• Evolution of techniques
• Innovation

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Conclusions

• Technological development requires
• Strong administration policy
• Partnership of all the road community

54
I whish you a very fruitful meeting on
performance based Road construction
technologyThank you for your attention !

• Kõszõnõm a figyelmúket !