EXPERIMENTAL WORK, DESIGN AND CONSTRUCTION OF ASPHALT BASES AND MEMBRANES IN COLORADO AND WYOMING

THE PROBLEMS OF EXPANSIVE SOIL SUBGRADES, EARLY CRACKING OF THIN ASPHALT PAVEMENTS, A GROWING SHORTAGE OF HIGH QUALITY AGGREGATES, FUND LIMITATIONS, AND A SHORT CONSTRUCTION SEASON LED THE COLORADO AND WYOMING STATE HIGHWAY DEPARTMENTS TO EXPERIMENT WITH ASPHALT MEMBRANES, AND FULL DEPTH ASPHALT PAVEMENTS. BASED ON CONSIDERATION OF MOISTURE MOVEMENTS, HYDROGENESIS, AND EQUIVALENCY RATIO DETERMINATIONS, THE FOLLOWING WAS CONCLUDED: (1) ASPHALT MEMBRANES EFFECTIVELY AND ECONOMICALLY MAINTAIN MOISTURE EQUILIBRIUM IN SUBGRADES; (2) FULL DEPTH ASPHALT BASES ARE EFFECTIVE IN REDUCING MOISTURE BUILD-UP IN SUBGRADE SOILS; (3) GRANULAR UNTREATED BASES ARE GOOD WATER PRODUCTION SYSTEMS, COLLECTING MOISTURE FROM THE ATMOSPHERE, THUS ESTABLISHING HYDROGENESIS AS A MAJOR CONTRIBUTOR TO SUBGRADE SATURATION; (4) ASPHALT BASE/UNTREATED BASE EQUIVALENCY RATIOS OF 2 OR 3 TO 1 ARE REASONABLE AND UNDER SOME CIRCUMSTANCES MAY BE CONSERVATIVE; (5) SOIL SUPPORT VALUES UNDER FULL DEPTH ASPHALT BASES ARE CONSIDERABLY HIGHER THAN UNDER GRANULAR BASES WHEN COMPARED TO SIMILAR CONDITIONS DUE TO MAINTAINING A DRYER ENVIRONMENT. FULL DEPTH ASPHALT BASE IS BEING USED ROUTINELY, WHEN WARRANTED BY CONSIDERATIONS OF AGGREGATE AVAILABILITY, HAUL LENGTH, PUBLIC CONVENIENCE, LENGTH OF CONSTRUCTION SEASON, STRENGTH COEFFICIENTS OF THE BASES AND SURFACINGS. IN GENERAL, A LONGER HAUL RESULTS IN A LOWER COST FOR PLANT MIX BASE WHILE A SHORTER HAUL IS GENERALLY FAVORABLE TO UNTREATED BASE COURSES.

• Authors:
  • Brakey, B A
  • CARROLL, J A
• Conference:
  • Association of Asphalt Paving Technologists Proc
• Publication Date: 1971

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 31-63
• Serial:
  • Volume: 40

Subject/Index Terms

• TRT Terms: Asphalt pavements; Bituminous aggregates; Bituminous bases; Flexible pavements; Haul distance; Moisture barriers; Moisture content; Motion; Pavements; Soil water; Specifications; Subgrade (Pavements); Thickness
• Uncontrolled Terms: Membranes; Moisture movement
• Old TRIS Terms: Asphalt pavement specifications; Membranes (Biology); Pavement course thickness; Subgrade moisture
• Subject Areas: Construction; Highways; Pavements;

Filing Info

• Accession Number: 00206013
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 15 1972 12:00AM