Asphalt Binders

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Asphalt Binders
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Introduction

• Terminology / Uses
• Sources / Manufacturing
• Composition / Product Types
• Temperature Susceptibility
• Specifications / Testing
• Modifiers / Additives

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Terminology

• Asphalt/Bitumen
• A mixture of heavy carbon-based compounds
  containing a high percentage of multiple-ring
  aromatics, many involving sulfur, nitrogen and
  oxygen atoms
• hydrocarbons soluble in CS2
• Brown-Black semi-solid material which is solid at
  room temp but softens and flows when heated
• Asphalt Cement - binder - oil
• Asphalt Concrete - Pavement
• Asphalt Cement plus Aggregate

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Asphalt Uses

• Paving Material
• Preservative / Protection
• Waterproofing / Roofing
• Insulator / Adhesive / Lubricant
• Industrial Building Material
• Fuel oil - Bunker, LIFO, MIFO
• Conversion Feedstock
• produce lighter petroleum products - gasoline,
  diesel etc

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Asphalt Uses
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Asphalt Uses
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Asphalt Uses
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Asphalt Uses
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Asphalt Uses
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Asphalt Uses
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Asphalt Sources

• Native or Natural Asphalts
• bitumens with inorganic impurities
• Trinidad lake has 25-50 insolubles
• Asphaltites - no impurities, high asphaltene
  content
• Gilsonite - Eastern Utah
• Rock Asphalts -- asphalt in rock
• impregnated sandstones - Oklahoma
• tar sands - Alberta
• oil shales - Colorado

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Asphalt Sources

• Tars - distillation of coal
• Pitch is distillation residue of tar
• Petroleum asphalts from crude oil

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Manufacturing

• Asphalts produced from crude oil
• Crude Oil Taxonomy - 18 Classes
• Light, Intermediate, heavy
• Sweet, Intermediate, Sour
• Paraffinic, Napthenic
• Best crudes for paving asphalts are heavy
  napthenic crudes

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Crude Oil

• Crude oil is found as a natural deposit on the
  earths surface or buried up to 18,000 ft deep
• First oil wells were drilled in China in 347 AD
  using bits attached to bamboo poles and achieved
  depths up to 800 ft
• Modern oil era was originally driven by kerosene
  oil for lamps
• Edisons light bulb reduced demand but was offset
  by internal combustion engine gasoline

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Petroleum Deposit of Western Canada

• Western Canada has the complete spectrum of
  hydrocarbons from light sweet crude to tar sands
• Generally oil is heavier towards the northeast.
  That is the closer to the Rockies, the lighter
  the crude.
• Lloydminister heavy oil can be produced by
  conventional means while Cold Lake can only be
  recovered by thermal stimulation
• The tar sands must be physically mined

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Refining Crude

• Most impact on the asphalt properties is from the
  crude source but the manufacturing process can
  also have an effect
• There are 80 refineries in North America
  producing asphalt - 5 in Western Canada
• Typically integrated refineries produce asphalt
  as a by-product, but there are dedicated asphalt
  refineries as well.
• Primary asphalt manufacturing is by fractional
  distillation

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Refining Crude
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Cracked Asphalts

• Very poor paving materials
• breaking down large hydrocarbons into smaller
  molecules through the application of temperature
  pressure and use of catalysts
• Thermal crackers
• Cokers
• Catalytic Cracking
• Hydrocracking

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Constitution of Asphalt

• Asphalt - colloid multiphase mixture of millions
  of different components

Identification by groups of components
Asphalt
heptane
methanol toluene
asphaltenes
TCE
toluene
polar aromatics
naphthene aromatics
saturates
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Asphaltenes

• Dark brown or black solids insoluble in nonpolar
  solvents
• Elemental composition varies only over narrow
  range

Carbon 82 ? 3 Hydrogen 8.1 ? 0.7

• General belief that unaltered asphaltenes have a
  definite composition
• Notable variation in the proportion of
  heteroatoms
• Oxygen 0.3 -4.9
• Sulphur 0.3 - 10.3
• Nitrogen 0.6 - 3.3

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Asphaltenes
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Resins

• Dark semisolid or solid, very adhesive fractions
• Soluble in liquids that precipitate asphaltenes
• C/H ratio 7.5 9.1
• Hydrogen 9.5 11
• Polycyclic structures with 56 rings (23
  aromatic on which there are aliphatic substituents

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Oils

• Lowest molecular weight hydrocarbons in asphalt
• Similar to lubricating oils - highest boiling
  fraction of lubricants
• Control the harness of asphalt
• Single or condensed naphthene and aromatic rings
  with side chains of varying length

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Oils

• mono-, di-, polynuclear aromatics
• C/H ratio 6.8 8
• molecular weight 240 800, most 360 500

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Structure and Colloidal Properties of Asphalts

• Physical properties of asphalt f (dispersion of
  asphatenes in maltenes)
• Peptizing effect of aromatic and resin portions
  of maltenes keep the colloidal structure of
  asphalt
• Prime consideration - rate of absorption of
  higher MW maltenes on the asphaltene particles
  f(time, temperature)

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Structure and Colloidal Properties of Asphalts
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Asphalt Products

• Asphalt Cements
• reduce viscosity by heating
• Cutback Asphalts
• reduce viscosity by blending with a solvent
• RC, MC, SC
• Asphalt Emulsions
• Asphalt in water - or inverted
• Anionic or Cationic - charge of particles
• RS, MS, SS

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Asphalt Testing

• Penetration
• Viscosity (shear rate)
• Softening Point (R B)
• Ductility
• Flashpoint (COC, PM)
• Solubility (TCE)
• TFOT, RTFOT
• Mass Loss, Aging Index

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Specifications

• Classical Specifications were designed to
  describe the material not its performance
• Recent specifications (CGSB ) have incorporated
  some performance criteria
• Superpave specifications are used to define
  performance using new methods of measuring
  properties

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