Asphalt Materials

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

Paving asphalt Asphalt cement Cutback asphalt Emulsified asphalt

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

Composition Asphalt cement Water Emulsifying agent

May contain a stabilizer

Asphalt Emulsions

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 PLANT

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

Cationic emulsions are preferred for acidic aggregates and anionic emulsions for basic aggregates