1. Use of Public Roads New perspectives in mixture designing Role 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 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 km²
Population : 63 Millions
1 million kms of roads
Notional Roads km
Toll Motorways km
Free motorways km
Routes de liaisons km
Departments km
Cities km

4. French Roads : some figures
Transfer to local authorities 1/1/2006
: RN kms
Average traffic: 20 à v/j
Temperate climate  θ surface -15°C, + 60°C, average 15°C

5. French Roads : some figures
Remark: legal axle load 130 kN

6. An example of performance based methodology French Bituminous Mix Design Methodology

7. Principle
One material type for each need Optimized with performance based criteria In relation with its use on the road

8. Mix design and Composition
Standard Performances Lab study
Gradation & Binder content designer’s choice
100
Formulation tool: Gyratory Compactor
(PCG) 90 80
ECF 70
BBSG 60
BBM
Paasing [%] 50
BBTM 40
BBUM 30
BBDr 20 10
Sieve [mm]
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 Compaction Water sensitivity Level 1 Level 2 Rutting
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
Modulus test
Stiffness
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
Marshall test

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. Manufactoring % voids Plate compactor: 400*600*150 or 180*500*25 à 100EN
ex NFP
Mixer BBMAX 80
Vertical gamma Bench
EN ex NFP )
(EN ex NFP )

15. Compactability characterisation
Gyratory compactor
Standard (NF ex NFP )
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, R = 1,38 (% voids 60 g)
MLPC Gyratory shear compactor

16. Typical result
Void content (%)
Repetability 0,95
Reproducibility 1,34

17. Interpretation of gyratory compaction test
Conformity study of a mix in relation to product standard specification for each material type ( NFP to 141)
Void content
Pass
Failed
Failed

18. Void content versus layer thickness In site compaction process
% voids
12 cm 5 8 6 10 4 20 2 8 16 26
Number of passes

19. Gyratory compactor test: specifications2 4 6 8 10 12 14
BBAC
(binder)
BBAGG
BBME
GB 2
GB 3
EME 1
EME 2
Voids %
On spec
Out of spec

20. Water sensitivity : Duriez test
Standard NFP
Two compaction efforts:
D< 14 mm H 190 mm, 60 kN, 5 min
D>14 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 )

21. Level 2 : rutting resistance test

22. LPC Wheel tracking test

23. LPC Wheel tracking test
Standard (EN ex NFP
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 60°C
Rut depth measurement

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
60 °C
Surface
Base 20
Out of spec 16 12
Rut depth [%] 8
On spec 4
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

31. Fatigue resistance test
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
Traffic direction
Wearing course
Base
Sub-base
Natural soil
Bituminous
Layers
Thickness t
Stiffness E
e, s
(tension)
Non treated
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) 15°C, 0,02s

34. Complex modulus test E pavement design 15°C, 10 Hz
r = 335 MPa , R = 2750 MPa
(E = MPa)
EN ex NFP
2 points bending on trapezoidal samples, 4 repetitions
E pavement design 15°C, 10 Hz
Master curve (rheological behavior)

35. Stiffness Modulus @ 15°C: complex (10 Hz) or tensile (0,02 s) 20000
18000
16000
14000
On spec
12000
Modulus [MPa]
10000
8000
6000
4000
Out of spec
2000
BBA
BBA
BBME
BBME
GB 2-
GB 4
EME
1-2 3 1
2-3 3
1-2

36. Fatigue test 6 Standard EN 12697-24 ex NF P 98-261-1
2 points Bending beam on trapezoidal samples
B=56, b=25, t=2, h=250 mm
3 strain levels with 6 specimens each, 10°C 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 @ 10 °C and 25 Hz [µstrain]
150
140
130
e6 [µstrain]
120
On spec
110
100 90 80
Out of spec 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
Spécifier par les classes et par niveau
level1
Giratory, water sensitivity

39. Trends in bituminous mixtures evolutions Dissociation 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 l’innovation)

46. Innovation policy For more than 25 years
Strong input of French administration:
Innovative Techniques Concourse
Technical advices (avis techniques)
Innovation protocol (charte de l’innovation)

47. Innovation policy - examples
Innovation protocols
(chartes de l’innovation)
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

50. 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

53. Conclusions Technological development requires
Strong administration policy
Partnership of all the road community

54. Kõszõnõm a figyelmúket !
I whish you a very fruitful meeting on performance based Road construction technology Thank you for your attention !
Kõszõnõm a figyelmúket !