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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 - 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 Superficies 550 000 km² Population : 63 Millions 1 million kms of roads Overview of the French Road Natwork 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 Temperate climate  θ surface -15°C, + 60°C, average 15°C Average traffic: 20 à 60 000 v/j

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

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

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

8  Standard Performances Lab study  Gradation & Binder content designer’s choice Typical grading curves 0 10 20 30 40 50 60 70 80 90 100 0.1110 Sieve [mm] Paasing [%] ECF BBSG BBM BBTM BBUM BBDr Formulation tool: Gyratory Compactor (PCG) Mix design and Composition

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) Duriez test Rutting test Modulus test Fatigue test Formulation selected Level 1 Level 2 Level 3 Level 4 Compaction Water sensitivity Rutting Stiffness Fatigue

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 Mixer BBMAX 80 Plate compactor: 400*600*150 or 180*500*25 à 100 Vertical gamma Bench EN 12697-33 ex NFP 98-250-2 EN 12697-35 ex NFP 98-250-1) (EN 12697-7 ex NFP 98-250-5)

15 MLPC Gyratory shear compactor  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(N e )  N e nbr of cycle as thickness [mm]  r = 0,95 R = 1,38 (% voids 60 g) Compactability characterisation

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

17 Void content Failed Interpretation of gyratory compaction test  Conformity study of a mix in relation to product standard specification for each material type ( NFP 98- 130 to 141) Pass

18 % voids Number of passes 2 2616 8 20 10 5 4 6 8 12 cm Void content versus layer thickness In site compaction process

19 0 2 4 6 8 10 12 14 BBAC (binder) BBAGG BBME GB 2GB 3 EME 1EME 2 Voids % On spec Out of spec Gyratory compactor test: specifications

20 Water sensitivity : Duriez test  Standard NFP 98-251-1  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 12697-12)

21 Level 2 : rutting resistance test

22 LPC Wheel tracking test

23 Wheel Rut depth measurement  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 60°C LPC Wheel tracking test

24 Rutting Number of cycles Average Regression Typical results with the LCPC wheel tracking

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 @ 60 °C 0 4 8 12 16 20 BBA 1 2 3 BBME 1 2 3 GB 2 to 4 EME 1-2 Rut depth [%] Surface Base Number of cycles 10 000 30 000 10 000 30 000 Out of spec On spec

31 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 Traffic direction Wearing course Base Sub-base Natural soil Bituminous Layers Thickness t Stiffness E  (tension) Non treated 

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  EN 12697-26 ex NFP 98 260-2  2 points bending on trapezoidal samples, 4 repetitions  E pavement design 15°C, 10 Hz  Master curve (rheological behavior) r = 335 MPa, R = 2750 MPa (E = 15300 MPa)

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

36 Fatigue test  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6

37 Fatigue test  Admissible strain @ 10 °C and 25 Hz [µstrain] 70 80 90 100 110 120 130 140 150 BBA 1BBA 2BBA 3BBME 1 2-3 GB 2GB 3GB 4EME 1 2    [µstrain] Out of spec On spec

38 level1 Giratory, water sensitivity Level 2 Level 3 Level 4 Permanent deformation Stiffness Fatigue Summary of the French mix design methodology

39 Trends in bituminous mixtures evolutions Dissociation of layer functions : base = structure wearing course = surface caracteristics. 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 EXPERIMENTATIONS SURVEYS CONCLUSIONS - DECISION CERTIFICATE AGREMENT PROTOCOL

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 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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