PAVES THE WAY. BITUMEN. Tar Natural Asphalt / Rock Asphalt / Lake Asphalt Bitumen. Types of Binders. Produced from Wood or Coal by destructive distillation process Coke Oven Tar Produced at temperatures above 1200 O C during manufacturing of coke. High aromatic content.
Coke Oven Tar
Produced at temperatures above 1200OC during manufacturing of coke.
High aromatic content.
Pitch content - 50 %.
Low Aromatic Tar
Produced at temperatures 600OC to 700OC.
Paraffinic in nature.
Pitch content - 35 %.Tar
A VISCO - ELASTIC MATERIAL
At higher temperature &/or longer loading time
Behave as viscous liquids
At low temperature &/or short loading time
Behave as elastic solids
The intermediate range of temperatures, more typical of the conditions in service, result in visco-elastic behaviour.Engineering Properties of Bitumen
B I T U M E N
Increases Softening Point, reduces Penetration Index, increases Viscosity
Reduces Shear Susceptibility
Bitumen performs the desired function on the road
Does not fail under predictable loads
Resists deterioration of road with time
Is able to withstand expected climatic conditions
Mix easily and form strong bond with a wide variety of aggregates
Is safe to handle
Modified Bitumen and Bitumen Emulsions should be a stable mixture in storage and handlingWhat is expected from Bitumen?
Withstand high temperatures – Softening Point
Withstand repetitive loading/unloading – Ductility
Withstand low temperatures – Fraass breaking point
Ease of mixing with aggregate – Viscosity at 135OC
Safety in handling - Flash point
Purity – Solubility in Trichloroethylene
Weight to volume conversion – Specific gravity
Deterioration of properties w.r.t. time and temperature – Thin Film Oven TestWhat properties need to be tested?
Fraass Breaking Pt
Higher softening point.
Suited for traffic intensity > 1500 cv/day.
Can withstand heavier axle loads.
Better suited for highways, expressways & urban roads.
Suited for areas where difference between min. & max. temp. is > 25oC.
Reduced stripping in presence of water.Applications of 60/70 Grade
Suited for traffic intensity > 1500 cv/ day
Used in metropolitan areas.
Used in airport runways.Applications of 30/40 Grade
Use of OGFC reduces Tyre Spray, Hydroplaning and Improves Visibility
Better contrast with pavement markingsSafe
Pave during off peak hours and open to traffic as soon as it cools down
Reduces work zone accident
Can result in 80% reduction in user delay costs
24-hour closure will have 3 to 10 times more vehicles pass through the work zoneSpeed of Construction
3 dB(A) corresponds to
Doubling the distance in the line of source
Reducing traffic volume by 50%
Reducing traffic speed by 25%
Open graded Friction Course
Reduces noise further
Costs 1/8th of noise barrier on side of the road
Aesthetically superiorQuiet Pavements
Very low level of leachable compounds
Most recycled product in the world
Second highest - Aluminium cans – 60%
Can use waste material from other fields also like worn out PCCEnvironment Friendly
New tests being developed
New plants providing high quality materials
Pavers with laser controlled screeds for even smoother pavements
Better material transfer vehicles for uniformity and rollers with increased compactive effort.
The ultimate result of this new technology will be: smoother, more durable, longer lasting asphalt pavementsState-of-the-Art
Also snow and ice melt quickly from bituminous pavementsDe-icing Materials
Can be easily trenched, patched and quickly opened to traffic when underground utilities need to be repaired.Serviceability
Binder of the future
Increasing Number of Vehicles
Increasing Axle Load
Desire to maintain higher serviceability level
Higher fatigue resistance
Higher resistance to weathering
Higher stiffness modulus
Lesser cracking, ravelling, deformation & creep failure
Reduce number of overlays
Reduction in vehicle operation costWhy Modified Bitumen?
Ethylene-prppylene-diene terpolymer (EPDM)
Isobutene-isoprene copolymer (IIR)
Ethylene vinyl acetate (EVA)
Ethylene methyl acrylate (EMA)
Ethylene butyl acrylate (EBA)
Atactic polypropylene (APP)
Polyvinyl chloride (PVC)
Trinidad lake Asphalt (TLA)
Fly ashTypes of Modifiers
SBS, SBR etc.
LDPE, EVA, EBA
UK Environmentalist’s want use of CRMB to be encouraged on roads. Govts. especially are considering making the use mandatory.
Belgian Road Research Center is encouraging the use of CRMB on Freeways
South African companies are increasingly using Rubber Modified mixes
International Use of Crumb Rubber Modified Bitumen
Voluntary activity driven by individual companies or by the national asphalt industry.
To obtain management and marketing tools.
In several countries certification is becoming a regulatory requirement, usually by mutual agreement between suppliers and clients.
Effective quality schedules can be produced only by joint action of supplier and client side of road sector.
If the positive aspects of certification are not taken into account in contract arrangements its introduction will increase the overall cost of asphalt roadsISO Certification of Roads
Fresh project proposals
Existing network of roads
Specific existing project
Auditors should be completely independent of the organization involved in development of project.
The audit team comprising of 4-5 people inspect the roads during daytime and also at night.
The team identifies aspects that the road controlling authority does well, as well as the aspects that could be improved.Road Safety Audit
Most tests are empirical tests and are not directly related to performance on the road
Tests are conducted at one standard temp.
Performance under climatic condition prevailing throughout the year are not evaluated
Only short term ageing is evaluated, that too only in a few cases
Performance grade tests simulate the actual field conditions in a more realistic wayPerformance Grade Specifications
Even surface gives better riding comfort.
Texture gives good skid resistance & relatively low traffic noise.
Strong aggregate structure provided by the coarse aggregate particles gives excellent resistance to permanent deformation.
Rich mastic, which fills the voids, makes SMA highly durable.
Modified bitumen & Fibres can be used to further enhance the mechanical properties.
Allows thin layer application.Stone Mastic Asphalt
When hot bitumen (160 to 200OC) comes in contact with cold water (15 to 25OC)
Mixture expands more than 10 times
Forms a fine mist or foam
Foamed bitumen is sprayed on fine aggregate in mixing drums to get a strong flexible pavement material
Used for durable, fast and low cost rehabilitation of existing pavementsFoamed Bitumen
Is added to the hot mix
Melts and disperses easily
Acts as binder extender and asphalt mix modifier
Reduces Bitumen requirement by 30%
Mixing temperature is reduced by 10OC
Higher resistance to rutting, fatigue failure and low temperature cracking
Suitable for perpetual pavementsSulphur Extended Asphalt Modifier