THE ASPHALT INSTITUTES LAYER EQUIVALENCY PROGRAM

THE PRIMARY OBJECTIVE OF THE ASPHALT INSTITUTES LAYER EQUIVALENCY PROGRAM IS TO DEVELOP AUTHENTIC ENGINEERING DATA THAT CAN BE USED TO PROMOTE THE SUBSTITUTION OF ASPHALT PAVING MIXTURES FOR COMPETITIVE PAVING MATERIALS AND FOR PART OR ALL OF THE GRANULAR BASE AND SUBBASE REQUIRED FOR CONVENTIONAL ASPHALT PAVEMENT, THEREBY PROVIDING A DEEP STRENGTH OR FULL DEPTH ASPHALT PAVEMENT. THIS DEVELOPMENT IS OF PARTICULAR INTEREST TO PETROLEUM REFINERS BECAUSE IT WOULD INCREASE THE ASPHALT DEMAND PER MILE OF PAVEMENT FROM TWO TO FIVE TIMES OR MORE. THE TERMS PAVEMENT, CONVENTIONAL ASPHALT PAVEMENT, DEEP STRENGTH ASPHALT PAVEMENT, FULL DEPTH ASPHALT PAVEMENT, AND LAYER EQUIVALENCY ARE DEFINED. IT IS RECOGNIZED THAT DEEP STRENGTH AND FULL DEPTH ASPHALT PAVEMENTS WILL BE SUBSTITUTED FOR CONVENTIONAL ASPHALT PAVEMENT ONLY WHEN THIS CAN BE DONE AT EQUAL OR LOWER COST. THE IMPORTANT FACTORS THAT FAVOR THESE PAVEMENTS OVER CONVENTIONAL ASPHALT PAVEMENTS AND OTHER COMPETITIVE PAVEMENTS TYPES ARE CONSIDERED. THESE INCLUDE A LARGE REDUCTION IN THE QUANTITIES OF GRANULAR MATERIAL REQUIRED PER MILE OF PAVEMENT, THE RAPID LOSS OF EFFICIENCY WITH INCREASING THICKNESS IN REGARD TO LOAD CARRYING CAPACITY PER INCH OF THICKNESS, THE ABILITY OF PRONOUNCED SLAB ACTION OF A COLD ASPHALT PAVING MIXTURE TO COMPENSATE FOR LOSS OF STRENGTH BY THE UNDERLYING SUBGRADE DURING SPRING BREAK-UP, REDUCTION OF EXCAVATION AND OF PAVING MATERIALS REQUIRED. HOT-MIX ASPHALT BASE PROVIDES GREATER LOAD CARRYING CAPACITY PER INCH OF THICKNESS THAN PORTLAND CEMENT BASE. METHODS FOR REDUCING THE COST OF HOT-MIX ASPHALT BASE PER MILE OF PAVEMENT INCLUDE THE USE OF LARGER MAXIMUM SIZE AGGREGATE, COMPACTION OF THE PAVING MIXTURE TO AT LEAST 100% OF LABORATORY COMPACTED DENSITY BY ROLLING DURING CONSTRUCTION, AND CONSTRUCTION IN THICKER LAYERS TO ACHIEVE LONGER HEAT RETENTION PERMITTING THE PAVING MIXTURE TO BE ROLLED TO 100% OF LABORATORY COMPACTED DENSITY. THE PRINCIPAL AUTHORITATIVE DATA ON LAYER EQUIVALENCIES WERE PROVIDED BY THE AASHO ROAD TEST. THE ASPHALT INSTITUTE PLANS TO OBTAIN SIMILAR LAYER EQUIVALENCY VALUES FOR OTHER TYPES OF ASPHALT BASE COMPOSITIONS SUCH AS HOT-MIX SAND ASPHALT, MIXTURES OF AGGREGATES WITH ASPHALT EMULSIONS AND WITH CUTBACK ASPHALTS, PENETRATION AND MIXED MACADAM, AND SOIL-ASPHALT MIXTURES, AND TO OBTAIN FURTHER LAYER EQUIVALENCY DATA FOR HOT-MIX ASPHALT CONCRETE.

  • Supplemental Notes:
    • 52 Pp, 17 FIG, 2 TAB, 14 REF
  • Corporate Authors:

    Imperial Oil Limited

    111 St Clair Avenue West
    Toronto, ONo,   Canada 
  • Authors:
    • McLeod, N W
  • Publication Date: 1966-3

Subject/Index Terms

Filing Info

  • Accession Number: 00210563
  • Record Type: Publication
  • Source Agency: CANADIAN GOOD ROADS ASSOCIATION
  • Files: TRIS
  • Created Date: Jan 23 1994 12:00AM