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TENSILE STRENGTH OF BITUMINOUS CONCRETE

The objective of this study was to evaluate factors that influence the tensile strength of bituminous concrete. The variables considered when making these measurements were grade of asphalt, asphalt content and testing temperature. Three grades of asphalt cement were used; AC-5, AC-20 and AC-40. The asphalt content for the specimen were varied from 5.0 to 7.0 percent of mixture. The specimens were tested at three temperatures; 140, 72 and 0 deg F. The analyses of the indirect tensile strength indicated that asphalt content had little or no influence but the asphalt viscosity grade showed some influence. As the temperature of the specimens were lowered the indirect tensile stresses increased generally in a direct logarithmic proportion. A determination of indirect tensile stiffness was evaluated relative to the three independent variables. This facet of the study indicated that the AC-20 samples had a stiffness value of 750,000 psi versus 400,000 psi for the AC-5 samples. This indicated the AC-20 had a stiffness nearly twice the value of AC-5 at the same temperature. This statement could be interpreted to mean that the AC-5 mix will be as stiff at -20 deg F as the AC-20 will be at -4 deg F using AC-20, then thermal cracking for AC-5 should not develop until -40 deg F. Based on these results the AC-5 asphalt provided the greatest resistance to tensile stresses at very cold temperatures. The results of this study indicated that while asphalt may be graded by viscosity at warm temperatures, 140 deg or 275 deg F, the properties are not predictable at cold temperatures. (Author)

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 32 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00386710
  • Record Type: Publication
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Aug 30 1984 12:00AM