FUNCTIONS OF FILLERS IN BITUMINOUS MIXES

A FILLER DEFINED AS THAT FRACTION OF AN INERT MINERAL DUST PASSING THE 200-MESH SIEVE IN A BITUMINOUS MIXTURE CAN PERFORM SEVERAL FUNCTIONS. ONE FUNCTION IS THAT OF FILLING VOIDS IN COARSER AGGREGATES, WHICH INCREASES THE DENSITY, STABILITY, AND TOUGHNESS OF A CONVENTIONAL BITUMINOUS PAVING MIXTURE. ANOTHER, IS THE CREATION OF A FILLER-ASPHALT MASTIC IN WHICH THE PARTICLES OF DUST EITHER MAY BE INDIVIDUALLY COATED WITH ASPHALT OR ARE INCORPORATED INTO THE ASPHALT IN MECHANICAL AND COLLOIDAL SUSPENSION. THESE FORMS OF MASTIC ARE PRODUCED BY SPECIAL PROCESSES, SUCH AS COOKING, ATOMIZED ASPHALT, AND FOAMED ASPHALT. IN PAVING MIXTURES THE MASTIC SERVES AS THE CEMENTING AGENT. THE EFFECT OF FILLERS IN CONVENTIONAL-TYPE MIXES IS PRONOUNCED. EXCESS QUANTITY OF FILLER TENDS TO INCREASE STABILITY, BRITTLENESS, AND PROCLIVITY TO CRACKING. DEFICIENCY OF FILLER TENDS TO INCREASE VOID CONTENT, LOWER STABILITY, AND SOFTEN THE MIX. IN MASTIC MIXES THE QUANTITY OF FILLER USED IS NOT CRITICAL. WHEN FILLER PARTICLES ARE INDIVIDUALLY COATED WITH THIN FILMS OF ASPHALT, STRONG, STABLE, TOUGH MIXES MAY BE PREPARED COMPOSED OF 100 PERCENT FILLER WITH 20 TO 25 PERCENT OF ASPHALT. IN MIXES WHEREIN THE FILLER IS IN SUSPENSION IN THE ASPHALT (SUCH AS THE HOT LIQUID ASPHALT MASTIC MIXES, GUSSASPHALT, ROOFING, AND WATERPROOFING COMPOUNDS) THE FILLER-ASPHALT MASTIC IS THE CEMENTING AGENT. THE PROPERTIES OF THE FILLER-ASPHALT MASTIC ARE INFLUENCED BY THE QUANTITY OF FILLER IN SUSPENSION. AN ASPHALT CEMENT OF 200 PLUS PENETRATION CONTAINING 30 TO 40 PERCENT OF FILLER WILL FORM A CEMENTING AGENT OR BINDER HAVING A PENETRATION OF ABOUT 10. HOWEVER, THE ASPHALT CEMENT ITSELF STILL RETAINS ITS ORIGINAL PENETRATION. THIS PHENOMENON HAS BEEN OBSERVED IN RELATION WITH NATURAL ASPHALTS (SUCH AS TRINIDAD), WHICH CONTAIN MINERAL DUSTS IN SUSPENSION. THE USE OF SUCH MASTICS IN PAVING MIXTURES PERMITS USE OF HIGHER DUST QUANTITIES AND HIGHER MIXING TEMPERATURES, YIELDING TOUGHER DENSER MIXES. SPECIAL MIXING PROCESSES (SUCH AS COOKING, ATOMIZED ASPHALT, OR FOAMED ASPHALT) ARE REQUIRED TO PRODUCE SUCH MIXES. /AUTHOR/

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  • Authors:
    • Csanyi, Ladis H
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  • Publication Date: 1962

Media Info

  • Media Type: Print
  • Features: References;
  • Pagination: pp 1-5
  • Monograph Title: Symposium on mineral fillers for bituminous mixtures
  • Serial:

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Filing Info

  • Accession Number: 00210832
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Aug 19 1994 12:00AM