25 - Understanding design of flexible pavements and types of aggregates

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En provenance du cours de École des Ponts ParisTech

Mastering bitumen for better roads and innovative applications

91 notes

École des Ponts ParisTech

Mastering bitumen for better roads and innovative applications

91 notes

During the four coming weeks, best experts in bitumen will bring you their knowledge and experience to build a strong understanding of today’s realities and new perspectives on the future of bitumen. Total is the European leader on bitumen markets. Innovation has always been the key to sustainability and durability in the products they develop. Their main objective here is to share technical knowledge and experience to insure bitumen are being used in the most effective and efficient ways for their different applications in road works. Ecole des Ponts, France oldest engineering school, remains very much in the present, as it has always been, in training engineers in order to meet the needs of our society and citizens in key areas such as transport housing and urban services, but also in fields like energy, environment, climate sciences, land-use planning and sustainable development. Nineteen world recognized experts on bitumen are contributing to this MOOC. The idea is to provide the broadest prism on this topic area with speakers coming from research, industry and end users.

À partir de la leçon

Modifications of bitumen and applications (roads, roofing,…)

Modifications using polymers. Performance of PmB. Elastic recovery test. | of types of modifications of bitumen: CRMB, warm mix asphalt, temperature reduction | Bitumen emulsions, their components, manufacture, storage, handling, properties, classification, uses | surface treatments | design of pavements and types of aggregates | fundamental tests, the simulative tests (fatigue test, rutting test, giratory compactor,…) | interest of full scale testing of asphalt mix: example of IFSTTAR carousel | Hot mix plants, transport, laying and compaction of asphalt mix | physical characteristics and industrial applications for sealing.

21 - Polymer modified bitumens8:00

22 - Other types of modifications of bitumen: CRMB, temperature reduction6:15

23 - Bitumen emulsions9:45

24 - Surface treatments7:44

25 - Understanding design of flexible pavements and types of aggregates7:59

26 - Laboratory testing of asphalt mix9:06

27 - Full scale testing of asphalt mix: IFSTTAR carousel6:44

28 - Hot mix plants, transport, laying and compaction of asphalt mix6:52

29 - Roofing applications of bitumen - other binders and uses (clear binders,...)5:23

Rencontrer les enseignants

Eric GOSSE
Vice Président
TOTAL MARKETING SERVICES
Armel de la BOURDONNAYE
Directeur
ECOLE DES PONTS PARISTECH
Sophie LIMBORG
Mission Head
TOTAL MARKETING SERVICES
Mike SOUTHERN
Director
Bituconsult LTD
Clémence QUEFFELEC
Assistant professor
CEISAM laboratory, University of Nantes, France
Gilles GAUTHIER
Technical and Product development manager
TOTAL BITUMEN
Olivier GAMET
Production Pilot
Supply department / TOTAL
John D'ANGELO
Chief Operating Officer
D’Angelo Consulting, LLC.
Gary SCHOFIELD
Technical Manager
Total Bitumen (UK)
Nicolas HAUTIERE
Project Director
IFSTTAR / COSYS Department
Frédéric ANDRZEJEWSKI
Expert bitumen industrial roofing activity
Jean Pascla PLANCHE
Vice President
Asphalt and Petroleum Technologies / Western Research Institute
Virginie MOUILLET
PhD, Senior Researcher, deputy head of chemical Unit
Regional Laboratory of Aix-en-Provence / Cerema Méditerranée
Hélène AZOULAY
Deputy Managing Director
PFC/Ecole des Ponts
Nadège VO VINH
Bitumen Shipping Manager
Supply International Bitumen / TOTAL MARKETING SERVICES
Cécile GIACOBI
Pavement expert
Vinci Autoroutes
Laurence LAPALU
Bitumen Group Manager
TOTAL MARKETING SERVICES - Research Division
Yves BROSSEAUD
senior researcher - road materials expert - materials and Structures Department
IFSTTAR - Nantes - France
Emmanuel CHAILLEUX
Research Director
IFSTTAR
Jean-François CORTE
Member of the Council of Environment and Sustainable Development
French Ministry of Environment, Energy and Sea

[MUSIC]

Hello I am Pierre Hornych from IFSTTAR.

I'm head of the laboratory In charged of research activities on pavement testing,

design and modeling.

The objective of this video is to present the principles

of the design of bituminous pavement.

The video will first present the characteristics

of bituminous pavements structures and mechanical behavior and failure modes.

Then it will explain the principles of the French pavement layout.

The pavement structure consists of three main layers.

The sub grade, the road base and the surface course.

The sub grade is the natural soil It is often covered with a copping layer,

consisting of granular material, or cement treated soil.

The role of the copping layer, is to protect the natural soil and

improve its the bearing capacity.

The tension of the road base, is to support the traffic loads, and

to spread the loads in the sub-grade.

The world base can be divided in two layers, the base layer and the sub base.

The surface course has two functions.

To protect the road base and to ensure good surface characteristics,

evenness, skid resistance, evacuation of water.

On heavy traffic pavements it can consist of two layers.

The wearing course and the binder course.

Bituminous pavements can be divided into two groups.

Low traffic pavements which consist of a single bituminous wearing course

generally less than 12 cm thick and a granual base.

These pavements are limited in France to traffic slower than 150 heavy

vehicles per day.

Thick bituminous pavements which have a bituminous wearing course and

a bituminous road base with a thickness varying generally between 15 and 40 cm.

Each type of pavement layer presents different failure mechanisms.

Surface courses can present different modes of deterioration, rutting,

wear, stripping, cracking, due in particular to aging or thermal fatigue.

The deterioration of surface course is considered as a maintenance problem and

it is generally not taken in to account in design.

Bituminous base layers present mainly fatigue cracking

due to repeated tensile stresses in use by the traffic loads

at the bottom of bituminous layers and also layer the bonding.

Unbound layers and soils present mainly permanent deformations

rutting due to the vertical stresses applied by the traffic.

The objective of pavement design is to define the pavement structure materials,

layer thicknesses, satisfying the constraints of the project.

Type of road, traffic level, design life, and budget.

At first I will present some general principles of pavement design,

then I will focus on the example of the French pavement design method.

Most recent pavement design methods can be defined as mechanistic empirical methods.

Because they are based on the mechanical pavement model

adjusted by the introduction of empirical calibration coefficients

Determined by comparison with performance of real pavements.

Mechanistic-empirical pavements design methods

are generally based on the following principles.

A multi-layer linear elastic model

is used to calculate the critical strengths in the pavement structure.

And given standard equivalent single axle load or easel.

The material properties used in the model, the modulus, and

the fatigue strength of each material are determined from laboratory tests.

Each calculated critical strain is compared with the limit value or

design criterium.

The figure on the right presents the results of the review

of 17 different design methods, used for bituminous pavements.

Two design criteria are almost universally used.

Fatigue criteria for bituminous layers.

And permanent deformation criterium for

the sub-grade, and for unbound granular layers.

However, some methods also introduce additional design criteria

based on other failure mechanisms.

Rutting of bituminous layers, top down cracking or thermal cracking.

The French pavement design method considers only the two most

common design criteria, fatigue and permanent deformations.

The pavement model is used to calculate two critical strains.

The maximum tensile strain at the bottom of the bituminous layers.

This tensile strain is compared with limit value to avoid fatigue failure.

The maximum vertical strain at the top of the sub-grade.

This vertical strain is compared again

With a limit value to avoid excessive permanent deformations.

This slide presents the fatigue design criteria

used in the French pavement design method.

This criterion is based on the fatigue load determined from laboratory fatigue

tests which defines the number of load cycles leading to fatigue failure.

This fatigue law is then adjusted by several coefficients.

This slide presents the permanent deformation criterion for the sub-grade.

This criterion is empirical and defines the limit vertical strain, epsilon lim.

In function of the number of load cycles,

this criterion can also be applied to unbound granual layers.

The french pavement design method is described in the french standard

NF-P-98086 Road Pavement Structural Design.

This method is also implemented in the design software ALIZE- LCPC.

Reminder of the key points.

Pavements structures consist of 3 main layers, the subgrade,

the road base which is the main structure of element and

the surface course which determines the surface characteristics.

Bituminous pavements present two main structural failure modes.

The fatigue of bituminous layers and

the permanent deformation of the sub grade and unbound general layers.

The French pavement design method is based on linear elastic pavement model and

defines the fatigue criterion to calculate the design life of

the bituminous layers, and permanent deformation criterion

to calculate the design life of the sub-grade.

Thanks for your attention.

[MUSIC]

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