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VALUE ADDED BITUMEN. Mankind is driven forward by dim apprehensions of things too obscure for it’s existing language. Zen and the Art of Motorcycle Maintenance, Robert M. Pirsig .
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Mankind is driven forward by dim apprehensions of things too obscure for it’s existing language. Zen and the Art of Motorcycle Maintenance, Robert M. Pirsig
What is Bitumen? A viscous liquid or a solid, consisting essentially of Hydrocarbons and their derivatives, which is soluble in Trichloroethylene and is substantially non-volatile and softens gradually when heated. It is Black or Brown in colour and posses water proofing & adhesive properties. It is obtained by refining processes from Crude Petroleum.
B I T U M E N A VISCO - ELASTIC MATERIAL
Engineering Properties of Bitumen • Bitumen is a visco-elastic material & it’s deformation under stress is a function of both temperature & loading time • 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.
The Stiffness Concept In solids : E = s e where E = Elastic modulus s = Stress e = Strain
The Stiffness Concept St,T = s et,T Where St,T = Stiffness modulus at specific time t & Temp. T. s = Stress et,T= Strain at specific time t & temp. T.
COMPOSITION B I T U M E N
Elemental Analysis Carbon 82 - 88 % Hydrogen 8 - 11 % Sulphur 0 - 6 % Oxygen 0 - 1.5 % Nitrogen 0 - 1 %
Chemical Composition • Bitumen • Asphaltenes(5 to 25 % wt.) • Maltenes • Saturates(5 to 20 % wt.) • Aromatics(40 to 65 % wt.) • Resins(10 to 20 % wt.)
Elemental Analysis • Elemental composition depends on • origin of crude • processes used in refinery • Elemental composition • Extremely complex with the number of molecules with different chemical structures being very large • Not feasible to attempt a complete analysis • Elemental composition provides little information of the types of molecular structure
Properties of BITUMEN
Properties of Bitumen Characteristics 80/100 60/70 30/40 Specific gravity at 27OC 0.99 0.99 0.99 Softening Point OC 35 to 50 40 to 55 50 to 65 Penetration at 25OC, 100gm, 80 to 100 60 to 70 30 to 40 5 secs., 1/10 mm Ductility at 27OC, in cm min. 75 75 50
SIGNIFICANCE OF TESTS • Penetration Test • Indicates consistence • Softening Point • Indicates melting temperature • Loss on heating / thin film oven test • Hardening on road • Ductility Test • Affinity for aggregates • Solubility in Trichloroethelene • Indicates purity of Bitumen
Penetration • Travel in dmm of a specified needle under 100 g wt. for 5 secs into Bitumen at 25OC • Denotes consistency
Softening Point • 3.5 g steel ball placed on Bitumen sample in Brass ring • Bath temp. raised at 5OC per minute
DUCTILITY • Indicates the extent to which a sample can be stretched before breaking. • Length in cm. at breaking point is ductility
FLASH POINT • Used to measure temperature to which a sample bitumen may be safely heated • The flash point is the temperature reached when the vapour causes an instantaneous flash
Value Added Bitumen • Cutback • Bitumen Emulsions • Modified Bitumen • Modified Bitumen Emulsions • Multigrade Bitumen
CUTBACK BITUMEN
CUTBACK BITUMEN • Manufactured by blending solvents like Kerosene with Bitumen • Free flowing liquid at ambient temperature • Used for tack coat and prime coat applications.
Types of Cutbacks • Rapid Curing (RC 70, 250, 800, 3000) • For aggregate passing 2.36 mm sieve • Medium Curing (MC 70, 250, 800, 3000) • For less than 20% aggregate passing 2.36 sieve • Slow Curing (SC 70, 250, 800, 3000) • For more than 20% aggregate passing 2.36 sieve
BITUMEN EMULSIONS
Bitumen Emulsion • Chocolate brown free flowing liquid at ambient temperature • Stable dispersion of fine globules of bitumen in continuous water phase • Dispersion is obtained by processing bitumen and water under controlled conditions through a colloidal mill with selected additives.
Types of Bitumen Emulsion • Cationic Bitumen Emulsion & Anionic Bitumen Emulsion. • Anionic not used for road work as aggregates are generally siliceous. • Cationic Bitumen Emulsions used in roadwork worldwide.
Emulsion Ingredients • Bitumen (80/100) • Emulsifier • Chemicals / additives • Water
Emulsification • Bitumen milled into fine particles & held in molecular spaces of water • Use of correct emulsifier / chemicals facilitate proper emulsification
Breaking • Electrostatic attraction causes breaking of emulsion • Bitumen +ve charge • Aggregate -ve charge • Result : excellent bonding / antistripping between bitumen & aggregate
Types of Cationic Emulsions • Slow Setting • Medium Setting • Rapid Setting
MODIFIED BITUMEN Binder of the future
Why Modified Bitumen? Demands on Road increasing every year • Increasing Number of Vehicles • Increasing Axle Load • Desire to maintain higher serviceability level • Higher fatigue resistance • Higher resistance to weathering • Better adhesion • Higher stiffness modulus • Lesser cracking, ravelling, deformation & creepfailure • Reduce number of overlays • Reduction in vehicle operation cost
Types of Modifiers Synthetic Elastomers SBS, SBR etc. Polymers Plastics Rubbers Crumb Rubber Natural Rubber (Latex) Thermoset Epoxy Resins Plain Thermoplastic LDPE, EVA, EBA Chemically Treated
Properties of Modifier • Be compatible with Bitumen • Blend with Bitumen properly & thoroughly • Improve temperature resistance of Bitumen • Resist degradation of Bituminous mix • Be capable of being processed by conventional mixing plants and laying machinery • Produce coating viscosity at application temp. • Maintain premium properties during storage,application and in service. • Be cost-effective considering life cycle cost
MODIFIED BITUMEN EMULSIONS
MODIFIED BITUMEN EMULSIONS • It is an Emulsion of Modified Bitumen • Has the advantages of Modified Bitumen & Emulsions both • Natural Rubber Modified Bitumen Emulsions • Polymer Modified Bitumen Emulsions
MULTIGRADE BITUMENS
MULTIGRADE BITUMEN • Resists cracking at low temperature • Resists deformation at high temperature • Reduced rutting at heavy traffic loads • Reduced cracking due to high traffic frequencies • Resists Aging • Optimize adhesion • Optimize emulsability