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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.

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Presentation on theme: "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."— Presentation transcript:

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 100
EN 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: specifications
2 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

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 !

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