Asphalt Paving Materials

transcript

Chapter 6

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Bituminous Materials

BituminousMaterials

NaturalAsphalts

PetroleumAsphalts

Tar &Pitch

(1800s) (late 1900s)(early 1900s)

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Natural Asphalt

Rock Asphalt Native AsphaltAsphalt Sand

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Asphalt Sands

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Asphalt Sands

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Native Asphalt

La Brea Tar Pits

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Native Asphalt

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Source: Geological Society of Trinidad and Tobago (www.gstt.org)

Native Asphalt

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Native Asphalt

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http://www.flickr.com/photos/striderv/4314238332/lightbox/

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Native Asphalt

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BituminousMaterials

NaturalAsphalts

PetroleumAsphalts

Tar &Pitch

(1800s) (late 1900s)(early 1900s)

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Chickamauga Coking Ovens

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Dunlap, TN Coking Ovens

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BituminousMaterials

NaturalAsphalts

PetroleumAsphalts

Tar &Pitch

(1800s) (late 1900s)(early 1900s)

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Crude Oil ChemistryOils

Resin-coated asphaltenes

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Crude Oil

AromaticHydrocarbons (oils)

SaturatedHydrocarbons

Light Crude Heavy Crude

“oils”“oils”

“oils”

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Petroleum Distillation

TubeHeater

Bitumen Residuum38-70 Carbons

DistillationColumn

Diesel Oil15-38 Carbons

Kerosene10-14 Carbons

Naphtha5-10 Carbons

Gasoline1-4 Carbons

Butane & Propane1-4 Carbons

550ºC

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Crude Oil

BitumenResiduum

GasolineKerosene

Lt. Gas Oil

Hv. Gas Oil

BoscanVenezuela

ArabianHeavy

NigeriaLight

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Liquefying Asphalt CementAsphalt Cement

(Bitumen Residuum)

Heatit

Suspendit in water

Thin it withsolvents

Hot-MixAsphalt

EmulsifiedAsphalt

CutbackAsphalt

Temperature-Viscosity

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Peanut Butter

Ketchup

Chocolate Syrup

Tomato Juice

Vegetable Oil

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Cutback Asphalt

Rapid Curing (RC)Asphalt cement thinned with gasoline or naphthaUsed for tack and seal coats (surface applications)

Medium Curing (MC)Asphalt cement thinned with keroseneUsed for prime coats, cold-laid pavement bases

Slow Curing (SC)Asphalt cement thinned with diesel oil or gas oilsUsed for cold-laid pavement bases

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Cutback Asphalt

70-140

250-500

800-1600

3000-6000

Solvent

Asphalt

Kinematic Viscosity@ 140°F (CS)

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Emulsified AsphaltWater & emulsifying agent

5-10 micron spheres of asphalt

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Emulsified Asphalt

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Emulsified Asphalt

LIMESTO

SILICA

Anionic Emulsifier Cationic Emulsifier

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Emulsified Asphalt

Rapid Setting (RS or CRS)Used for surface coats, penetration macadam

Medium Setting (MS or CMS)Used for open-graded asphalt-treated base

Slow Setting (SS or CSS)Used for dense-graded asphalt-treated base

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Asphalt Cement Grading

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Asphalt Cement Performance

ElasticSolid

TrueLiquid

ViscoelasticSolid

ViscousLiquid

FatigueCracking

RuttingShoving

DrainDown

ThermalCracking

AverageServiceTemp

MaximumServiceTemp

MixingPlacingTemp

MinimumServiceTemp

0ºF 300ºF130-150ºF75-80ºF

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Thermal Cracking

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Fatigue Cracking

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Fatigue Cracking

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Rutting

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Rutting

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Shoving

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Shoving

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Asphalt Cement Performance

ElasticSolid

TrueLiquid

ViscoelasticSolid

ViscousLiquid

PenetrationNumber

AbsoluteViscosity

KinematicViscosity

AverageServiceTemp

MaximumServiceTemp

MixingPlacingTemp

MinimumServiceTemp

0ºF 275ºF77ºF 140ºF

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Penetration Test

0 seconds 5 seconds

Penetration

Penetration Number = Penetration in tenths of a millimeter

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Asphalt Penetrometer

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Penetration GradingBased on penetration index at 77°F:

Grade 40–50Grade 60–70Grade 85–100Grade 120–150Grade 200–300

Must also meet ductility, flashpoint, and retained penetration (aging) criteria

Penetration Grading

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Ductility

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Ductility(Taken from The Asphalt Institute Manual ES-1, Second Edition)

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Thin-Film Oven Test

5-6 rpm5 hrs

Simulates aging of asphalt cement during mixing and laydown

samplepans

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Thin-Film Oven

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Penetration Grading

PRO· Done at average service temperature· Easy test, inexpensive equipment· Test is done at room temperature

CON· Empirical test· Doesn’t specifically address aging· Doesn’t capture temperature susceptibility

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Penetration Grading

Temperature

HotSummer

AverageService

ColdWinter

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Viscosity GradingBased on the absolute viscosity at 140oF:

AC-2.5AC-5AC-10AC-20AC-30AC-40

Must also meet ductility, penetration (77oF), kinematic viscosity (275oF), and aging criteria

Numbers correspondto absolute viscosityin hundreds of poiseTDOT

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Viscosity Grading

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Absolute Viscosity

• If a fluid with a viscosity = 1 Pa·s is placed between two plates and one plate is pushed sideways with a shear stress = 1 Pa it will move a distance equal to the thickness of the layer in one second.

Absolute viscosity of water at 20ºC = 0.001 Pa·s = 0.01 poise0.01 poise ≡ 1 centipoise

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Absolute Viscosity(Taken from The Asphalt Institute Manual ES-1, Second Edition)

VACUUM VACUUM

Asphalt InstituteViscometer

Cannon ManningViscometer

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Viscosity of Common MaterialsWater 1 centipoise

Cream 20 centipoise

Vegetable Oil 100 centipoise

Tomato Juice 200 centipoise

Honey 2000 centipoise

Chocolate Syrup 10000 centipoise

Sour Cream 20000 centipoise

Ketchup 50000 centipoise

Peanut Butter 150000 centipoise

Vegetable Shortening 1000000 centipoise

AC @ 275F

AC @ 140F

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Kinematic Viscosity

Absolute ViscosityKinematic Viscosity

Fluid Density

3cmg1poise1

stoke1

Kinematic viscosity of water at 20ºC = 0.01 stoke0.01 stoke ≡ 1 centistoke

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Kinematic Viscosity(Taken from The Asphalt Institute Manual ES-1, Second Edition)

Zeitfuchs Cross-Arm Viscometer

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Viscosity Grading

Temperature

HotSummer

MixingCompacting

AverageService

ColdWinter

77oF–10oF 275oF

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Viscosity Grading

PRO· Fundamental material property· Done at maximum service temperature· Includes high & average temperature criteria

CON· Harder to run, more expensive equipment· Doesn’t specifically address long-term aging· Doesn’t consider low-temperature cracking

Asphalt Paving Materials

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