Asphalt Binders ENCI 579
Introduction Terminology / Uses Sources / Manufacturing Composition / Product Types Temperature Susceptibility Specifications / Testing Modifiers / Additives ENCI 579
Terminology Asphalt/Bitumen Asphalt Concrete - Pavement 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 ENCI 579
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 ENCI 579
Asphalt Uses ENCI 579
Asphalt Uses ENCI 579
Asphalt Uses ENCI 579
Asphalt Uses ENCI 579
Asphalt Uses ENCI 579
Asphalt Uses ENCI 579
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 ENCI 579
Asphalt Sources Tars - distillation of coal Pitch is distillation residue of tar Petroleum asphalts from crude oil ENCI 579
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 ENCI 579
Crude Oil Crude oil is found as a natural deposit on the earth’s 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 Edison’s light bulb reduced demand but was offset by internal combustion engine gasoline ENCI 579
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 ENCI 579
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 ENCI 579
Refining Crude ENCI 579
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 ENCI 579
Constitution of Asphalt Asphalt - colloid multiphase mixture of millions of different components Identification by groups of components Asphalt heptane methanol + toluene asphaltenes TCE toluene naphthene aromatics polar aromatics saturates ENCI 579
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% ENCI 579
Asphaltenes ENCI 579
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 5~6 rings (2~3 aromatic on which there are aliphatic substituents ENCI 579
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 ENCI 579
Oils mono-, di-, polynuclear aromatics C/H ratio : 6.8 ~ 8 molecular weight : 240 ~ 800, most 360 ~ 500 ENCI 579
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) ENCI 579
Structure and Colloidal Properties of Asphalts ENCI 579
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Asphalt Products Asphalt Cements Cutback Asphalts Asphalt Emulsions 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 ENCI 579
ENCI 579
Asphalt Testing Penetration Viscosity (shear rate) Softening Point (R & B) Ductility Flashpoint (COC, PM) Solubility (TCE) TFOT, RTFOT Mass Loss, Aging Index ENCI 579
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 ENCI 579
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ENCI 579