BRITTLE FRACTURE OF ASPHALTIC MIXES

THE BRITTLE FRACTURE OF ASPHALTIC MIXTURES WAS INVESTIGATED BECAUSE CRACKING OF ASPHALTIC MIXTURES IS CONSIDERED TO BE A MAJOR PROBLEM FOR MOST TYPES OF ASPHALTIC SURFACES AND PAVEMENTS. A BRIEF REVIEW IS PRESENTED OF THE THEORETICAL CONCEPTS OF FRACTURE MECHANICS THAT ARE USED AS THE BASIS OF EXPLAINING AND EVALUATING THE CRACKING PHENOMENON IN ASPHALTIC CONCRETE. AN IMPACT TEST AND A NOTCH BEAM TEST WERE USED TO VERIFY THE THEORY. SEVERAL MIX PARAMETERS, SUCH AS ASPHALT CONTENT, CONSISTENCY, ETC., WERE USED TO STUDY THE BRITTLE RESISTANCE OF THE ASPHALTIC MIXTURES. THE RESULTS OF BOTH THE IMPACT TEST STUDY AND THE NOTCHED BEAM TEST STUDY INDICATE EXPERIMENTALLY A CORRELATION BETWEEN BOTH TESTS. BOTH TESTS PROVED TO BE VALUABLE TOOLS FOR STUDYING BRITTLE BEHAVIOR OF ASPHALTIC MIXTURES. THE NOTCHED BEAM TEST PROVIDES A MEANS FOR AN ACTUAL AND MORE THEORETICALLY EXPLAINED MEASURE OF THE BRITTLENESS OF THE ASPHALTIC MIXTURE. THE EASE AND SIMPLICITY OF THE IMPACT TEST AS WELL AS ITS QUALITATIVE NATURE CAN BE VERY USEFUL IN COMPARING THE RESISTANCE OF DIFFERENT MIXTURES TO BRITTLE FRACTURE. THE BRITTLE BEHAVIOR OF ASPHALTIC MIXTURES IS CONCLUDED TO BE A DIRECT FUNCTION OF THE TEST TEMPERATURE. THE BRITTLE RESISTANCE OF ASPHALTIC MIXTURES DECREASES TO A CRITICAL TEMPERATURE, AT AND BELOW WHICH MIXES BEHAVE IN A BRITTLE MANNER. THE TEMPERATURE AT WHICH THE MIXES START TO BEHAVE IN A BRITTLE MANNER APPEARS TO BE PRIMARILY A FUNCTION OF THE CONSISTENCY OF ASPHALT CEMENT. AT LOWER TEMPERATURES THE GRIFFITH THEORY OF BRITTLE FRACTURE IS APPLICABLE TO STUDY THE FRACTURE BEHAVIOR OF ASPHALTIC MIXTURES, SINCE THERE WAS NO NOTCH EFFECT INDICATED UPON THE BRITTLE RESISTANCE OF MIXES. THE PSEUDO- FRACTURE TOUGHNESS IS A MEASURE OF THE BRITTLE RESISTANCE OF ASPHALTIC MIXTURES. THE ASPHALT CEMENT CONSISTENCY, ASPHALT CONTENT AND UNIT WEIGHT OF MIXES ARE CONSIDERED TO HAVE A MAJOR EFFECT ON THE BRITTLENESS RESISTANCE OF MIXES AS MEASURED BY THEIR PSEUDO-FRACTURE TOUGHNESS. THE RATE OF DEFORMATION HAS A DIRECT EFFECT ON THE PSEUDO-FRACTURE TOUGHNESS OF THE MIXES.

• Supplemental Notes:
  • pp 1-34, 10 FIG, 4 TAB, 30 REF
• Authors:
  • BAHGAT, A G
  • Herrin, M
• Conference:
  • Assoc Asphalt Paving Technol Proc
• Publication Date: 1968-2

Subject/Index Terms

• TRT Terms: Asphalt; Asphalt cement; Asphalt pavements; Bituminous materials; Bituminous mixtures; Consistency; Crash tests; Deformation; Fracture mechanics; Notch tests; Pavement cracking; Surface treating; Temperature; Theory; Weight
• Old TRIS Terms: Bituminous surfacing; Unit weight
• Subject Areas: Highways; Materials; Research;

Filing Info

• Accession Number: 00210767
• Record Type: Publication
• Files: TRIS
• Created Date: May 21 1994 12:00AM