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• Asphalt


  A dark brown to black cementitious material, solid or semisolid in consistency, in which the predominant constituents are bitumens which occur in nature as such or are obtained as residue in refining petroleum
• Asphalt was used as far back as

  6000 BC
• Uses of asphalt in ancient times


  • Adhesives in boat building
  • Waterproofing in pools and baths
  • Paving streets and palace floors
  • Mummification process
  • Building material
• Natural asphalt


  Formed when crude petroleum oils rose to the earth's surface and formed pools, with the lighter oils and gases driven off by the sun and wind, leaving a heavy residue
• Locations of natural asphalt deposits

  • Bermudez Deposits in Venezuela
  • Asphalt lake on the Island of Trinidad
  • LaBrea Pits in Los Angeles, California
• Rock asphalt


  Asphalt impregnated in porous rock, with low asphalt content
• Gilsonite


  A hard, brittle, and relatively pure asphalt which can be economically extracted from the earth for commercial purposes
• Today the majority of asphalt used in construction is obtained from petroleum crude
• Bitumen


  A mixture of hydrocarbons of natural or pyrogenous origin or combination of both, accompanied by their nonmetallic derivatives, which may be gaseous, liquid, semisolid, or solid, and which are completely soluble in carbon disulfide
• Asphalt


  A dark brown to black cementitious material, solid or semisolid in consistency, in which the predominant constituents are bitumens
• Tar


  A brown or black bituminous material, liquid or semisolid in consistency, in which the predominant constituents are bitumens obtained as condensates in the destructive distillation of coal, petroleum, oil shale, wood, or other organic materials, and which yields substantial quantities of pitch when distilled
• Tar


  Resistant to petroleum-based solvents
• Asphalt


  Readily soluble in most petroleum products
• Tar is generally produced as a byproduct during the production of coal</b>
• Coal tars generally have high specific gravities, viscosities, and good adhesive properties
• Asphaltic base crude


  Crude oil that is almost entirely asphalt
• Paraffin base crude


  Crude oil that contains paraffin but no asphalt
• Mixed base crude


  Crude oil that contains both paraffin and asphalt
• API gravity


  The basis for the amount of asphalt obtained from a crude oil, with higher gravity indicating lower asphalt content and lower gravity indicating higher asphalt content
• Fractional distillation


  Crude oil is heated and the lighter oils vaporize and are drawn off at their condensation temperature, leaving a residual material - asphalt cement
• Destructive distillation


  Crude oil is heated under pressure to higher temperatures than used for fractional distillation, resulting in cracked asphalt which is durable and weather resistant but not used in highway surface construction
• Residual oil


  The material produced when the distillation is stopped while the residue is still liquid or semisolid
• Asphalt cement


  The material produced when the resulting product from distillation is solid or semisolid
• Blown asphalts


  Asphalts produced by blowing air through the residual oil at an elevated temperature, which oxidizes the asphalt and raises its softening point
• Cutback liquid asphalts


  Produced by cutting the asphalt cement with a petroleum solvent, classified as rapid-curing (RC), medium-curing (MC), or slow-curing (SC) based on the volatility of the solvent
• Asphalt emulsions


  Produced by separating the hot asphalt cement into minute globules and submersing them in water that has been treated with an emulsifying agent, with the asphalt as the discontinuous phase and the water as the continuous phase
• Anionic emulsion


  Asphalt emulsion where the asphalt globule has a negative charge
• Cationic emulsion


  Asphalt emulsion where the asphalt globule has a positive charge
• identification quizz