Modern Road Construction; A Practical Treatise for the Use of Engineers, Students, Members of Local Authorities, Etc

Modern Road Construction; A Practical Treatise for the Use of Engineers, Students, Members of Local Authorities, Etc

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 edition. Excerpt: ...good sign if the bitumen required more than 25 to 30 per cent. of the oil to bring it to a soft or pliable condition. The flux may in itself be unsuitable, or the bitumen may have a high melting-point. The oil that is sought for in those classes of bitumens that come within the conditions before mentioned will have a specific gravity between 0-92 and 0-94. The loss on heating for seven hours at 325 F. must not exceed 5 per cent. It should be soluble in 88 naphtha to an extent of 95 per cent. There must not be more than 10 per cent. left when testing for paraffin scale, and not more than 5 per cent. fixed carbon. Penetration or Viscosity.--In order to judge whether the consistency of a mixture is precisely the same as that of a sample, the prepared bitumen is poured into a fairly deep tin and allowed to cool to a temperature of 60 or 78 F., and is then submitted to a penetration test, which is performed by what is known as a penetrometer. Penetration Machines.--There are various machines which are used for the purpose--one is known as the Bowen penetrometer, another as the Dow penetrometer, and yet another as the New York testing penetrometer. Each of these machines consists of a needle, properly weighted, which is attached to a dial. The needle is brought to the surface of the bitumen, which has been maintained for some time in hot water at the desired temperature. It is then released by means of a spring for a period of 1 or 2 seconds, generally 1 second, and the reading of the penetration is taken from the dial. The Dow and the New York testing laboratory machines Fig. 18.--To make a test. The tar or bitumen to be tested is placed in a small tin under the needle, so that it just touches the surface, the pneumatic ball is pressed, and more

Product details

  • Paperback | 50 pages
  • 189 x 246 x 3mm | 109g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236562275
  • 9781236562272