The need for reduction for negative skin friction is discussed and the recommendation is made that the better knowledge of the soil conditions which in the first place made the engineer aware of the negative skin friction (and at the same time, of other factors influencing the piles) should be used to evaluate the pile capacity from a soil mechanical point of view. One such method of design evaluation is discussed in which the maximum allowable load on the pile from the superstructure is stipulated by the existing practice and the pertinent building code, and measures to reduce or counteract the negative skin friction will be necessary only if a thorough soil mechaincal study and structure analysis show that the otherwise allowed maximum load is too large. With regard to the thickness of the bitumen, the discusser states that unless the soil settlement conditions are extreme, there is no need for the thick coat recommended in the paper, particularly if a bitumen softer than the one (penetration 40/50) recommended by them is used. The use is recommended of bitumen of type penetration 85/100 specified by ASTM D-946 to be applied to a thickness of 1 mm to 2 mm. The bitumen may by applied by brushing or sprinkling after being heated. A primer may by needed to achieve adhesion in the case of precast piles. On occasions it may be necessary to mix the bitumen with a solvent, softening the bitumen enough to limit the necessary heating to approximately 170 deg F.

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Filing Info

  • Accession Number: 00096256
  • Record Type: Publication
  • Report/Paper Numbers: Discussion
  • Files: TRIS
  • Created Date: Jul 15 1975 12:00AM