THE SURFACE TENSION OF ASPHALTIC BITUMENS AND ALLIED SUBSTANCES AT VARIOUS TEMPERATURES

METHODS ARE DISCUSSED FOR THE DETERMINATION OF THE SURFACE TENSION OF ASPHALTIC BITUMENS. THE METHOD OF THE ADHESION RINGS (DU NOUY APPARATUS) SEEMS TO GIVE FAIRLY GOOD RESULTS BUT CANNOT BE CONSIDERED RELIABLE AND ACCURATE. IT IS CONTENDED THAT THE BEST METHOD SEEMS TO BE THAT OF THE AIR- BUBBLE PRESSURE. A STREAM OF PURE NITROGEN IS PRESSED THROUGH A CAPILLARY TUBE, THEN DIPPED INTO THE MOLTEN BITUMEN. FOR ASPHALTIC BITUMENS THE SURFACE TENSION COULD BE DETERMINED WITHIN A RATHER WIDE TEMPERATURE RANGE. DETERMINATION OF THE OILY CONSTITUENTS IN WHICH THE ASPHALTIC BITUMEN MICELLES ARE DISSOLVED IS DISCUSSED. EXTRACTION OF THE OILY CONSTITUENTS IS OUTLINED. THE FOLLOWING SUBSTANCES WERE ANALYZED: OXIDIZED VENEZUELAN ASPHALTIC BITUMEN, SPRAMEX (ROYAL DUTCH-SHELL), SHELFALT (ROYAL DUTCH-SHELL), 50-60, SHELFALT (ID.), 40-50, ASPHALTIC BITUMEN FROM TRINIDAD EPURE, AND COAL TAR PITCH. RESULTS SHOW THAT ALL CURVES HAVE A DEFLECTION POINT. BELOW A CERTAIN TEMPERATURE THE VALUES OBTAINED FOR THE SURFACE TENSION INCREASE RAPIDLY WITH DECREASING TEMPERATURE. IT IS CONCLUDED THAT, WHEN HEATING AN ASPHALTIC BITUMEN OR A PITCH, A SUDDEN DECREASE IN THE COHESION OF THE COLLOIDAL LIQUID OFTEN OCCURS. ABOVE THIS TEMPERATURE, THE ASPHALTIC BITUMEN AND THE PITCH BEHAVE LIKE AN ORDINARY HEAVY MINERAL OIL. DEFLECTION POINTS ARE GIVEN FOR THE DIFFERENT SUBSTANCES. THESE FIGURES SHOW THAT A LOWER PENETRATION OF THE ASPHALTIC BITUMEN DOES NOT ALWAYS CORRESPOND WITH A HIGHER DEFLECTION POINT. CURVES FOR THE OILY CONSTITUENTS SHOW A DEFLECTION POINT BUT AT A MUCH LOWER TEMPERATURE. THE TEMPERATURE DIFFERENCE BETWEEN THE DEFLECTION POINT OF THE ASPHALTIC BITUMENS AND THAT OF THE OILY CONSTITUENTS SHOWS WIDE VARIATIONS. REFERENCES; F. J. NELLERSTEYN, N. M. ROODENBURG, KOLLOID-CHEMISCHE BEIHEFTE, VOL. 31, P. 434, 1930.

  • Supplemental Notes:
    • Vol 9, pp 127-128, 2 FIG
  • Authors:
    • Nellensteyn, F J
  • Publication Date: 0

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  • Accession Number: 00210923
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 21 1994 12:00AM