6506-1 - BITUMINOUS MATERIALS BITUMEN - Black or dark brown...

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1 BITUMINOUS MATERIALS BITUMEN - Black or dark brown sticky substance composed principally of high- molecular-weight hydrocarbons soluble in Carbon Disulfide (CS 2 ). Carbon Disulfide is now replaced by Trichloroethylene (CHCl:Cl 2 ) in the solubility test. BITUMINOUS MATERIALS - substance in which Bitumen is present. For engineering purposes, Bituminous materials include mainly: (1) asphalt, (2) tar. Pitch - residue of tar after the volatile constituents are distilled off. COMPARISON BETWEEN ASPHALT AND TAR SIMILARITIES: (1) Composed principally of Bitumen. (2) Black or dark brown in color. (3) Cementitious. (4) Water repellent.
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2 DIFFERENCES: (1) Distinguished by odor (tar has an aromatic odor). (2) The insoluble portion in natural asphalt is mineral matter, while the insoluble in tar is free carbon. (3) Tar molecules tend to be aromatic (ring or cyclic), while asphalt molecules tend to be aliphatic (straight chain) C C H H C C H C C H H H Basic Benzene Aromatic H C H H C H H C H H C H H C H H C H Straight Chain (4) Tar is more temperature susceptible (5) Tar can coat aggregates better and is more water resistant. (6) Asphalt is more weather resistant
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3 (7) Asphalt can occur in natural form or come as a by-product of petroleum refinery. Tar does not occur in natural form, but comes as a by-product in the manufacture of coke or water-gas. (8) Fumes from heated tar cause health hazards such as severe eye and skin irritation. MAIN USAGES OF BITUMINOUS MATERIALS TODAY: (1) Road construction (2) Roofing (3) Water proofing material HISTORICAL BACKGROUND USES OF ASPHALT: (1) As adhesive and waterproofing materials: Ship building in Sumeria (6000 B.C.) Noah's Ark Basket which held Moses (2) Preservative: Mummification in Egypt (2600 B.C.) (3) Paving Material: Roads in the Inca Empire (A.D. 1300)
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4 TWO CATEGORIES OF ASPHALT (1) Natural Asphalt -Lake Asphalt -Rock Asphalt -Gilsonite (2) Petroleum Asphalt -from residuum of petroleum refinery NATURAL ASPHALTS 1. LAKE ASPHALT - occurs in form of a lake (A) Bermudez Asphalt - comes from Bermudez 'Pitch' Lake, Northern Coast of Venezuela - asphalt crude is dug out from the lake (B) Trinidad Asphalt - from Trinidad Asphalt Lake
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5 Bermudez 2. ROCK ASPHALT - found impregnated in Sandstone or Limestone. e.g. Kentucky Rock Asphalt - occurs in Sandstone impregnated with asphalt.
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This note was uploaded on 05/26/2011 for the course CGN 6505 taught by Professor Mang during the Spring '11 term at University of Florida.

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6506-1 - BITUMINOUS MATERIALS BITUMEN - Black or dark brown...

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