pavement materials aggregates part 1

8/20/2019 Pavement Materials Aggregates Part 1

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Highway Materials

Aggregates

Pavement Design (CE-2209)1

Soil Defnition (Engineering)“reers to all unconsolidated

material in the earth’s crust, allmaterial above the bedrock”mineral articles (gravel, sand, silt, cla!)

organic material (to soil, marshes)

"ggregatesmineral articles o a soilsecifcall!, granular soil grougravel, sand, silt


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Highway Materials

Aggregates

Pavement Design (CE-2209)#

$ranular Soil $rou ("ggregates)%h!sical &eatheringaction o rost, &ater, &ind, glaciers, lant'animals

articles transorted b! &ind, &ater, icesoils ormed are called granular soil t!e

“grains are similar to the original bedrock”

arger grain sies than cla!s

%articles tend to be more or lesssheres'cubes

*ound &ater is small comared to overallmass


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Pavement Design (CE-2209)+


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Highway MaterialsAggregates

Pavement Design (CE-2209)

$ranular Soil $rou ("ggregates)abilit! to achieve greater densities&ell graded granular material

increased soil strengthlo&er ermeabilit!reduced uture settlement

-hese imrovements dictate the useo aggregates in avement la!ers&here &heel loads are greater


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Highway Materials

Aggregates

Pavement Design (CE-2209).

/n combination &ith ashalt cement orortland cement to orm ashalt concreteor cement concrete resectivel!

/n subbases and bases o a road&a!structure

drainage structures

concrete blocks


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Highway Materials

Aggregates


-!es o "ggregates

*asic roerties o these aggregates -ests used to evaluate these roerties


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"ggregate Sourcesnatural sand or gravel deosits 2

crushed rock 2

slag and mine reuse

rubble and reuse

artifcial and rocessed materials

ulveried concrete and ashaltavements

other rec!cled and &aste materials


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4atural sand and gravel deositssand and gravel its

sand and gravel soils that have beennaturall! sorted to eliminate most o thesilt or cla! sies then deosited in5glacier ormations (eskers, out&ash lains)

river deositsbeaches o current and revious lakes and seas


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Sand ' $ravel %it DevelomentStriing o tosoil, vegetation7 rom surace

E8cavation o material

material is loose 9 ront end loaders:rushing o the materiallarger sie aggregate is broke do&n to desired sie

crushed gravel is considered high ;ualit! aggregate

&ashing o aggregate cleans dust removes silt'cla! -!e o material deends on bedrock sourceimestone, sandstone,granite,etc<


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Pavement Design (CE-2209)1=

:rushed >ock“-!e o aggregates roduced rom

;uarries deends on the t!e o

bedrock”:lasses o >ocks/gneous rocks

Sedimentar! rocks

?etamorhic rocks


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:rushed >ock/gneous >ocks@riginal bedrock ormed rom the cooling o molten

material:oarse grained igneous rock (granite) cooled slo&l!

Aine grained igneous rocks (basalt) cooled raidl!

Sedimentar! >ocksSolidifcation o chemical or mineral sediments

deosited under ancient seasa!ered since original material &as deosited in this

manner


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Pavement Design (CE-2209)1#

:rushed >ockSedimentar! >ocksimestone :alcium :arbonate

Dolomite :alcium'?agnesium:arbonate

Shale :la!

Sandstone Buart

:hert Aine sand:onglomerate $ravel


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Pavement Design (CE-2209)1+

:rushed >ock?etamorhic >ocks

/gneous or Sedimentar! rocks that have

been metamorhosed due to intense heatand ressureSlate shale

?arble limestone

Buartite sandstone$neiss granite


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:rushed >ock

/gneous and ?etamorhic rocks are ver!

hard and make an e8cellent source or

aggregates

imestone and Dolomite are commonsedimentar! rocks, are soter than igneous

rocks but are accetable or aggregates

Shale rimaril! comosed o cla! grains is&eak and disintegrates easil!

:hert also disintegrates easil!


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Highway Materials Aggregates

Pavement Design (CE-2209)1.

Buarr! %it Develoment@ening and Striing o the ace o the

;uarr!

*lasting o rock &ith d!namite into siesthat can be transorted

:rushing o rock into the re;uiredaggregate sies


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Slag and ?ine >euseSlag is a &aste material resulting rom the

treatment o ore to roduce iron, steel, nickel, ubble and >euserec!cling o ulveried concrete rom structuresrec!cled ashalt avements in base courses

rec!cled rubber, crushed glass in base courses


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-!es o "ggregatesAine "ggregateaggregate articles mainl! bet&een the


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-!es o "ggregates:rushed $ravelit gravel (or sand) that has been ut through a

crusher either to break the rounded gravelarticles into smaller sies or to roduce rougher

suraces

:rushed >ockaggregate rom the crushing o bedrock< "ll

articles are angular and not rounded as in gravelScreeningschis, dust, o&der that are roduced rom

crushing


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-!es o "ggregates:oncrete Sandsand that has been &ashed to remove dust

and fnesAinessilt, cla!, or dust articles smaller than

.Cm usuall! the undesirable imurities in

aggregates


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Pavement Design (CE-2209)#=

-!es o "ggregates4ominal Sie4ot economical to have 1== o the

articles o an aggregate be &ithin asecifed sie range<

>educing the reection rom a it in order toeFcientl! use the material resources o ait

Gsuall! . 9 1= o the aggregate articlescan be allo&ed to be larger or smaller thansecs


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Pavement Design (CE-2209)#1

-!es o "ggregates4ominal Sie:oarse aggregates 169


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Pavement Design (CE-2209)##

"ggregate %roerties$radation (grain sie anal!sis)grain sie distribution or high&a! bases and

bituminous mi8es that &ill rovide a dense strongmi8ture

ensure that the voids bet&een the larger articlesare flled &ith medium articles< -he remaining voidsare flled &ith still smaller articles until the smallestvoids are flled &ith a small amount o fnes<

Ensure ma8imum densit! and strength using ama8imum densit! curve


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Pavement Design (CE-2209)#+

-heoretical ?a8imum Densit! :urvesAuller ?a8imum Densit! :urve

% H (d'D)=


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Highway Materials

Aggregate Gradations

Strength or resistance to shear ailurein road bases and avements is

increased greatl! i the mi8ture isdense graded


#.


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Highway Materials

Aggregate Gradations

a) larger articles are in contact &ith eachother develoing rictional resistances toshearing ailure< %articles are tightl! bondtogether due to the inter9locking eKect osmaller articles< -his eKect is higher in (a)than (b)


#0


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Highway MaterialsAggregate Gradations


b) ?ust limit the amount o fnessilt and cla! articles are relativel! &eakdust on larger aggregates &ill interace

&ith the aggregate'bituminous bondE8cessive fnes in a base or subbase ma!

lead to drainage on rost heaving roblemsE8cessive fnes (smaller aggregates) results

in &eak structures because larger articles

are not in contact &ith each other strength Sn (smaller articles) are &eaker< -hereore managing o fnes is imortant<


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Lashed Sieve "nal!sisas a result it is imortant in determining the

amount assing the .µm sieve

samle is dried and &ashed, &ash &ater ouredout over the . µm sieve

material retained is returned to the samle orsieve anal!sis

total amount assing . µm is e;ual to the amount

lost in &ashing and assing . µm sieve


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E8amle 91 ?ass o samle 0etained in


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4ote5 @nl! =


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Pavement Design (CE-2209)+1

"ggregate %roerties$radation (grain sie anal!sis)Jigh densit! mi8tures are imortant in terms o

densit! and ashalt cement re;uired< "shalt mustcoat each article and fll in most o the void sace</ !ou fll in void sace &ith cheaer material suchas aggregates !ou save ashalt


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Highway MaterialsAggregate Sampling and Testing

Pavement Design (CE-2209)+#

pavement materials aggregates part 1

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