THE ADHESION OF BITUMINOUS BINDERS TO ROAD AGGREGATES

AN EXTENDED SERIES OF TESTS WAS CONDUCTED ON ADHESION OF BITUMINOUS BINDERS, USING THE RIEDEL AND WEBER METHOD ON FINE MATERIAL, 1/2-IN. CHIPPINGS, AND TRACING THE CONNECTION BETWEEN THE RESULTS OBTAINED AND THE MINERAL COMPOSITION, GRAIN-SIZE AND SURFACE TEXTURE OF THE AGGREGATES. NINE DIFFERENT KINDS OF BINDERS WERE USED, AND THE ADHESION OF THESE TO EACH OF 16 DIFFERENT AGGREGATES WAS STUDIED. SOME OF THESE BINDERS AND AGGREGATES WERE FURTHER TESTED BY MEANS OF THE GERMAN U.37 TEST AND ALSO BY MEANS OF THE MODIFIED OBERBACH TEST. THESE TESTS AND THE PROCEDURES ARE DESCRIBED. IT IS CONCLUDED THAT THE ADDITION OF MINERAL FILLER TO THE BINDER INCREASES ITS VISCOSITY AND SO HELPS TO REDUCE THE TENDENCY OF THE LATTER TO BE DISPLACED BY WATER. DIFFERENCES IN ADHESION ARE DUE MORE TO VARYING DEGREES OF ROUGHNESS OF THE AGGREGATE RATHER THAN TO DIFFERENCES IN ITS COMPOSITION. THE MINERAL COMPOSITION OF THE AGGREGATE IS OF IMPORTANCE ONLY INSOFAR AS IT AFFECTS SURFACE TEXTURE. THE GRAIN SIZE OF THE CONSTITUENT MINERAL IS A FACTOR EXCEPT FOR SLAGS. ADHERENT COATINGS SUCH AS LIMONITE IMPROVE THE ADHESION. NO SIMPLE MATHEMATICAL METHOD OF MEASURING THE DEGREE OF RUGOSITY OF THE EXTERIOR OF AN AGGREGATE HAS BEEN DEDUCED, BUT A MICROGRAPHIC PROJECTION GIVING A MAGNIFICATION 50 TIMES (LINEAR) OF THE EDGE OF THE AGGREGATE ENABLES THE TEXTURE OF A STONE TO BE COMPARED WITH ONE OF A SERIES SHOWN IN THE TABLE. THE REIDEL AND WEBER TEST IS EXTREMELY USEFUL FOR PRELIMINARY PURPOSES, BUT THE FAILURE OF A STONE UNDER THIS TEST DOES NOT NECESSARILY MEAN THAT IT IS INCAPABLE OF BEING BOUND. IF BAD RESULTS ARE OBTAINED IT CAN BE TESTED BY THE MODIFIED OBERBACH TEST, THE GERMAN U.37 TEST NOT BEING RECOMMENDED.

  • Supplemental Notes:
    • Vol 93, No 2400, PP 77-80, 15 FIG, 2 TAB
  • Authors:
    • Knight, B H
  • Publication Date: 1938-1-21

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  • Accession Number: 00210927
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 21 1994 12:00AM