A DESIGN PROCEDURE FOR ASPHALTIC CONCRETE MIXTURES

A RESEARCH PROJECT IS REPORTED ON A DESIGN PROCEDURE FOR ASPHALTIC CONCRETE SURFACING MIXTURES. THE GYRATORY TESTING MACHINE WAS USED BECAUSE OF ITS POTENTIAL AS A COMPACTION AND TESTING MACHINE. THE HVEEM STABILOMETER AND COHESIOMETER WAS USED TO PROVIDE A BASIS FOR THE SELECTION OF SUITABLE GYRATORY TESTING MACHINE TESTING CONDITIONS AND DESIGN CRITERIA, AND FOR COMPARISON OF FIELD AND LABORATORY MIXTURES. THE AIR-ROLLER WAS USED TO DENSIFY SAMPLES COMPACTED WITH THE FIXED-ROLLER. DESIGN ASPHALT CONTENTS AND AIR VOID CONTENTS WERE OBTAINED FOR FIVE AGGREGATE BLENDS USING THE CALIFORNIA DESIGN PROCEDURE. THE CALIFORNIA PROCEDURE PRODUCED LOWER DESIGN ASPHALT CONTENTS THAN THE GYRATORY COMPACTION METHODS. A COMPARISON OF THE AIR VOID CONTENT VALUES SHOWS THAT THE KNEADING AND GYRATORY FIXED- ROLLER COMPACTED SPECIMENS CONTAINED CONSIDERABLY LOWER AIR VOID CONTENTS THAN DID THE AIR-ROLLERS COMPACTED SPECIMENS. THE AIR-ROLLER COMPACTION PROCEDURE DEVELOPED PROVIDES AN ESTIMATE OF THE DENSITY OBTAINED BY FIELD COMPACTION AT THE TIME OF CONSTRUCTION. THE DIFFERENT DESIGN METHODS APPEAR TO GIVE SIMILAR DESIGN ASPHALT CONTENTS EVEN THOUGH IT IS DIFFICULT TO ASSESS ALL OF THE IMPLICATIONS INHERENT IN THE RESULTS PRESENTED. A METHOD FOR ESTIMATING THE DESIGN ASPHALT CONTENT FOR A MIXTURE WAS DEVELOPED AS FOLLOWS: INITIAL HOT-MIX COMPACTION WAS PERFORMED USING 12 REVOLUTIONS OF THE GYRATORY TESTING MACHINE WITH SETTINGS OF A 3-DEGREE ANGLE OF GYRATION, 100 PSI RAM PRESSURE, AND 15 PSI AIR-ROLLER PRESSURE. AFTER INITIAL COMPACTION, THE SAMPLE WAS SUBJECTED TO FURTHER DENSIFICATION BY THE TESTING MACHINE UNDER CONDITIONS OF 140 F TEMPERATURE, 2- DEGREE ANGLE OF GYRATION, 100 PSI RAM PRESSURE, AND A 20 PSI AIR-ROLLER PRESSURE. DENSIFICATION WAS EXTENDED TO 200 REVOLUTIONS. THE DESIGN ASPHALT CONTENT WAS CHOSEN AS THAT WHICH PRODUCED A SAMPLE HAVING A GYRATORY SHEAR VALUE OF 27.0 AFTER DENSIFICATION. 12 REVOLUTIONS OF THE AIR-ROLLER FOR INITIAL COMPACTION PRODUCED DENSITIES AND HVEEM STABILITY VALUES THAT APPROXIMATED FIELD VALUES WHEREAS FIXED ROLLER AND KNEADING COMPACTION VALUES EXCEEDED THE DENSITY AND STABILITY VALUES ATTAINED IN THE FIELD. A RELATIONSHIP WAS ESTABLISHED BETWEEN THE HVEEM STABILITY AND GYRATORY SHEAR. THIS RELATIONSHIP WAS USED TO ESTABLISH THE GYRATORY SHEAR VALUE OF 23.6 OR THE LOWER LIMIT REQUIRED FOR ACCEPTABLE PERFORMANCE OF PAVING MIXTURES.

• Supplemental Notes:
  • pp 1-55, 8 FIG, 12 TAB, 6 REF, 1 APP
• Authors:
  • Ruth, B E
  • Schaub, J H
• Conference:
  • Assoc Asphalt Paving Technol Proc
• Publication Date: 1968-2

Subject/Index Terms

• TRT Terms: Air voids; Asphalt concrete; Asphalt content; Bituminous materials; Bituminous mixtures; Compaction; Design; Gyratory testing machines; Hveem cohesiometer; Hveem stabilometer; Pavement design; Rollers; Shear strength; Stability (Mechanics); Surface treating
• Uncontrolled Terms: Design criteria; Gyratory compaction
• Old TRIS Terms: Air voids content; Bituminous surfacing; Cohesiometers; Gyratory tests
• Subject Areas: Design; Highways; Materials; Pavements;

Filing Info

• Accession Number: 00210763
• Record Type: Publication
• Files: TRIS
• Created Date: May 21 1994 12:00AM