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Asphalt - Definition:“A dark brown to black cementitious material
in which the predominating constituents are bitumens which occur in nature or are
obtained in petroleum processing.”
(ASTM D8 - 02 Standard Terminology Relating to Materials for Roads and
Pavements )
Asphalt Types
Natural asphalt deposits Natural evaporation of volatile portions of
petroleum leaving the asphalt fractions Lake asphalt
TrinidadBermudez
Rock asphaltNatural asphalt deposits in porous rock
Petroleum asphalt
Produced through the process of distillation of crude petroleumAccomplished by raising the temperature of the crude
in stagesDifferent fractions separate at various temperaturesLighter fractions - Simple distillationHeavy distillates - Vacuum distillation, solvent
extraction
Asphalt Types
TEMPERATURE
(F)
PERCENT DISTILLED
1000
900
800
700
600
500
400
300
200
100
00 10 20 30 40 50 60 70 80 90 100
ASPHALT
GAS OIL
DIESEL
KEROSENE
GASOLINE
GAS
Refining produces asphalt with specific characteristics for varied uses Paving asphalt Roofing asphalt Other special uses
Asphalt Types
Precautions Application temperatures are often higher
than flash point! Do not load hot AC into tanks which contain
cutback asphalt
Cutback Asphalt
Emulsified and Cutback Products
WATERAND
EMULSIFIER
GASOLINEOR
NAPHTHAKEROSENE
SLOWLY &NON-
VOLATILEOILS
ASPHALTCEMENT
ASPHALTCEMENT
ASPHALTCEMENT
ASPHALTCEMENT
SlowCuring (SC)CutbacksRoad Oils
MediumCuring (MC)
Cutbacks
RapidCuring (RC)
CutbacksAsphalt
Emulsions
Asphalt Emulsions A suspension of small globules of one liquid in a
second liquid with which the first will not mix: an emulsion of oil in vinegar
Major uses Surface treatments Patching Stabilization Slurry sealing Recycling
Factors which increased usage Energy crisis of 1970’s
Petroleum solvents not requiredUsed without additional heating
Reduced atmospheric pollution Ability to coat damp aggregates Variety of emulsion types Economical - less fuel consumption
Asphalt Emulsions
Emulsion technology Using mechanical and/or chemical processes to
combine two or more materials that would not mix under normal conditionsEmulsions used today were developed in 1920’s
Mayonnaise, paints, hair dyes, ice cream
Asphalt Emulsions
Anionic Grades RS - Rapid Setting MS - Medium Setting SS - Slow Setting
Mixing ability RS grades do not mix well with aggregates MS grades mix well with coarse but not fine aggregates SS grades mix well with fine aggregates
Cationic Grades CRS - Rapid Setting CMS - Medium Setting CSS - Slow Setting
Asphalt Emulsions
Asphalt Institute Basic Asphalt Emulsion Manual MS-19
Asphalt Emulsions
Water andEmulsifying Agent Asphalt Globules
Breaking - Separation of the water and asphalt globules
Typical Emulsion Nomenclature
CRS-2PCRS-2PCLASSIFICATION PREFIX
SUB-CLASSIFICATION
VISCOSITY SUFFIX
MODIFICATIONSUFFIX
Emulsion must be stable Asphalt particles remain in suspension
PumpingProlonged storageMixing
Emulsion should break easily Contact with aggregate in mixer Sprayed on road surface
After cure, asphalt retains original properties
Asphalt Emulsions
Classification Anionic
Negatively charged asphalt particles Cationic
Positively charged asphalt particles Dependent on type of emulsifying agent used
Asphalt Emulsions
Factors affecting breaking and curing Absorption rate of aggregates Aggregate moisture content Aggregate gradation - surface area Weather conditions - temp, humidity, wind Type and amount of emulsifying agent Intensity of aggregate charge Mechanical manipulation and rolling
Asphalt Emulsions
Storage and handling Store between 10° and 85° C (50° and 185° F) Use tall, vertical tanks for storage Do not used forced air to agitate Do not mix anionic and cationic grades Do not dilute RS grades with water MS and SS grades can be diluted
Add water to emulsion slowlyDo not add emulsion to tank of water
Do not add hot asphalt cement to emulsion tank
Asphalt Emulsions
Asphalt Plants
Stationary plants At a permanent location Often times materials are hauled to the plant from
other sources Portable plants
Moved from location to location Take advantage of aggregate sources close to the
job site
Items common to both plant types Site location Aggregate storage and cold feed system Aggregate drying and heating Dust collection system Asphalt storage tank(s) Plant control facility
Asphalt Plants