Asphalt PPT

7/24/2019 Asphalt PPT

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Asphalt


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Asphalt is one of the oldest materialsused in construction.

Asphalt binders were used in 3000B.C., preceding the use of the wheelby 1000years.

Asphalt came from various locationsaround the world.


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Trinidad lae asphalt


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Today, practically all asphalt cementis from re!ned petroleum.


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Types of asphalt products

Asphalt used in pavements is produced in 3 forms" Asphalt cement

Asphalt cutbac

Asphalt emulsion

At room temperatures, asphalt cement is a semisolidmaterial that cannot be applied readily as a binderwithout being heated.

#i$uid asphalt products, cutbacs and emulsions, havebeen developed and can be used without heating.

Although li$uid asphalt products are convenient, theycannot produce a $uality of asphalt concretecomparable to what can be produced by heating neatasphalt.


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Asphalt cement


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Asphalt cutbac A cutbac is produced by dissolving asphalt

cement in a lighter molecular weighthydrocarbon solvent.

%hen the cutbac is sprayed on a pavementor mi&ed with aggregates, the solvent

evaporates, leaving the asphalt residue asbinder.

'isadvantages" (etroleum cost have escalated and the use of

solvent is not anymore cost e)ective. Cutbacs are ha*ardous materials due to

volatility of solvents.

Application of cutbacs releases environmentally

unacceptable hydrocarbons into the atmosphere.


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Asphalt emulsion

An alternative to dissolving the asphalt in asolvent is dispersing the asphalt in water asemulsion as.

+n this process the asphalt cement is physicallybroen down into micronsi*ed globules thatare mi&ed into water containing an emulsifyingagent.

-mulsi!ed asphalt typically consist of about0/ to 0/ asphalt cement, 30/ to 0/ waterand a fraction of a percent of emulsifyingagent.


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2ses of asphalt

The main use of asphalt is inpavement construction andmaintenance. +n addition, asphalt is

used in sealing and waterproo!ngvarious structural components, suchas roofs and underground

foundations. The selection of the type and grade

of asphalt depends on the type of

construction and climate of the area.


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Asphalt cement

Also called asphalt binders, are usedtypically to mae hotmi& asphaltconcrete for the surface layer of

asphalt pavements.

+t is also used in patching andrepairing both asphalt and portland

cement concrete pavements.


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#i$uid asphalts emulsion and

cutbacs4

Are used for pavement maintenanceapplications, such as


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5og seals

A fog sealis a light application of a

diluted slowsetting asphalt emulsionto the surface of an aged pavementsurface. Fog sealsare lowcost and

are used to restore 7e&ibility to ane&isting 89A pavement


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Chip seals

Chipsealalso chip seal4 is apavement surface treatment thatcombines one or more layers4 of

asphalt with one or more layers4 of!ne aggregate.


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slurry seals A slurry sealis the application of a

mi&ture of water, asphalt emulsion,aggregate very small crushed roc4,and additives to an e&isting asphalt

pavement surface. A slurry sealissimilar to a fog seale&ceptthe slurry sealhas aggregates aspart of the mi&ture.


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9icrosurfacing A coldmi& e&pansion of slurry seal

with a higher polymer and asphaltresidual content, better $ualityaggregate and fastsetting

chemicals.

(aving applications of asphalt


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Term Description Application

8ot mi&asphalt

Carefully designed mi&ture ofasphalt cement and aggregates

(avement surface,patching

Cold mi& 9i&ture of aggregates and li$uid

asphalt

(atching, low volume road

surface, asphalt stabili*edbase

5og seal :pray of diluted asphalt emulsionon e&isting pavement surface

:eal e&isting pavementsurface

(rime coat :pray coat asphalt emulsion to

bond aggregate base and asphaltconcrete surface

Construction of 7e&ible

pavement

Tac coat :pray coat asphalt emulsionbetween lift of asphalt concrete

Construction of newpavements or between ane&isting pavement and anoverlay

Chip seal :pray coat asphalt emulsion orasphalt cement or cutbac4followed with aggregate layer

9aintenance of e&istingpavement or low volumeroad surfaces

:lurry seal 9i&ture of emulsion, wellgraded!ne aggregate and water

;esurface low volumeroads

9icrosurfacin

9i&ture of polymer modi!edemulsion well raded crushed

te&turing., sealing, crac!llin rut !llin and minor

(aving applications of asphalt


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(erformance grade binder

characteri*ation

:everal test are used in theperformance grade method tocharacteri*e the asphalt binder.

( i l


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(ressure aging vessel

+t is designed to simulate the

o&idative aging that occurs in asphaltbinders during pavement service.

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5lash point At high temperature, asphalt can 7ash or

ignite in the presence of open 7ame or

spar. The 7ash point test is a safety testthat measures the temperature at which7ashes.


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; t ti l


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;otational


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Documents

Asphalt PPT