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8/20/2019 Aggregates ENCI579 Lecture4
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ENCI 579 4 1
Highway Materials, Soils, and Concrete
Aggregates• Soil Definition (Engineering)
– “refers to all unconsolidated aterial in t!e
eart!"s crust# all aterial a$o%e t!e
$edroc&'
• ineral articles (gra%el# sand# silt# cla)
• organic aterial (to soil# ars!es)
• *ggregates – ineral articles of a soil
– secificall# granular soil grou
• gra%el# sand# silt
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Highway Materials, Soils, and Concrete
Aggregates• ,ranular Soil ,rou (*ggregates)
– -!sical .eat!ering
• action of frost# .ater# .ind# glaciers# lant/anials• articles transorted $ .ind# .ater# ice
• soils fored are called granular soil te
• “grains are siilar to t!e original $edroc&'
– 0arger grain sies t!an clas
– -articles tend to $e ore or less s!eres/cu$es
– 2ound .ater is sall coared to o%erall ass
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Highway Materials, Soils, and Concrete
Aggregates• ,ranular Soil ,rou (*ggregates)
– a$ilit to ac!ie%e greater densities
• .ell graded granular aterial
– increased soil strengt!
– lo.er erea$ilit
– reduced future settleent
• !ese iro%eents dictate t!e use of
aggregates in a%eent laers .!ere .!eel
loads are greater
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Highway Materials, Soils, and Concrete
Aggregates• In co$ination .it! as!alt ceent or
ortland ceent to for as!alt concrete or
ceent concrete resecti%el• In su$$ases and $ases of a road.a
structure
• drainage structures
• concrete $loc&s
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ENCI 579 4
Highway Materials, Soils, and Concrete
Aggregates
• es of *ggregates
• 2asic roerties of t!ese aggregates
• ests used to e%aluate t!ese roerties
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Highway Materials, Soils, and Concrete
Aggregates• *ggregate Sources
– natural sand or gra%el deosits 6
– crus!ed roc& 6
– slag and ine refuse
– ru$$le and refuse
– artificial and rocessed aterials – ul%eried concrete and as!alt a%eents
– ot!er reccled and .aste aterials
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Highway Materials, Soils, and Concrete
Aggregates
• Natural sand and gra%el deosits
– sand and gra%el its
– sand and gra%el soils t!at !a%e $een
naturall sorted to eliinate ost of t!e silt
or cla sies t!en deosited in8
• glacier forations (es&ers# out.as! lains)• ri%er deosits
• $eac!es of current and re%ious la&es and seas
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Highway Materials, Soils, and Concrete
Aggregates• Sand / ,ra%el -it De%eloent
– Striing of tosoil# %egetation fro surface
– E:ca%ation of aterial
• aterial is loose ; front end loaders
– Crus!ing of t!e aterial
• larger sie aggregate is $ro&e do.n to desired sie
• crus!ed gra%el is considered !ig!
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Highway Materials, Soils, and Concrete
Aggregates• Crus!ed ?oc&
– “e of aggregates roduced fro
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Highway Materials, Soils, and Concrete
Aggregates• Crus!ed ?oc&
– Igneous ?oc&s
• Ariginal $edroc& fored fro t!e cooling of olten
aterial
• Coarse grained igneous roc& (granite) cooled slo.l
• Bine grained igneous roc&s ($asalt) cooled raidl
– Sedientar ?oc&s
• Solidification of c!eical or ineral sedients deosited
under ancient seas
• 0aered since original aterial .as deosited in t!is
anner
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Highway Materials, Soils, and Concrete
Aggregates• Crus!ed ?oc&
– Sedientar ?oc&s
• 0iestone Calciu Car$onate• Doloite Calciu/@agnesiu Car$onate
• S!ale Cla
• Sandstone uart
• C!ert Bine sand
• Congloerate ,ra%el
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Highway Materials, Soils, and Concrete
Aggregates• Crus!ed ?oc&
– @etaor!ic ?oc&s
– Igneous or Sedientar roc&s t!at !a%e $eenetaor!osed due to intense !eat and
ressure
• Slate s!ale
• @ar$le liestone
• uartite sandstone
• ,neiss granite
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Highway Materials, Soils, and Concrete
Aggregates• Crus!ed ?oc&
– Igneous and @etaor!ic roc&s are %er !ard and
a&e an e:cellent source for aggregates
– 0iestone and Doloite are coon sedientar
roc&s# are softer t!an igneous roc&s $ut are
acceta$le for aggregates
– S!ale riaril coosed of cla grains is .ea&and disintegrates easil
– C!ert also disintegrates easil
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Highway Materials, Soils, and Concrete
Aggregates
• uarr -it De%eloent
– Aening and Striing of t!e face of t!e
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Highway Materials, Soils, and Concrete
Aggregates• Slag and @ine ?efuse
– Slag is a .aste aterial resulting fro t!e treatent
of ore to roduce iron# steel# nic&el# ==
• 2last furnace slag fro iron ills is a coonaggregate
– @ine tailings can also $e used for aggregates
• ?u$$le and ?efuse
– reccling of ul%eried concrete fro structures
– reccled as!alt a%eents in $ase courses
– reccled ru$$er# crus!ed glass in $ase courses
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Highway Materials, Soils, and Concrete
Aggregates• es of *ggregates
– Bine *ggregate
• aggregate articles ainl $et.een t!e 4=75 sie and t!e 75u sie%e=
– Coarse *ggregate
• aggregate articles ainl larger t!an 4=75
– -it ?un
• aggregate fro a sand or gra%el it .it! no
rocessing
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Highway Materials, Soils, and Concrete
Aggregates• es of *ggregates
– Crus!ed ,ra%el
• it gra%el (or sand) t!at !as $een ut t!roug! acrus!er eit!er to $rea& t!e rounded gra%el articles
into saller sies or to roduce roug!er surfaces
– Crus!ed ?oc&
• aggregate fro t!e crus!ing of $edroc&= *ll articles are angular and not rounded as in gra%el
– Screenings
• c!is# dust# o.der t!at are roduced fro crus!ing
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Highway Materials, Soils, and Concrete
Aggregates
• es of *ggregates
– Concrete Sand
• sand t!at !as $een .as!ed to reo%e dust and fines
– Bines
• silt# cla# or dust articles saller t!an 75u usuall
t!e undesira$le iurities in aggregates
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Highway Materials, Soils, and Concrete
Aggregates
• es of *ggregates
– Noinal Sie
• Not econoical to !a%e 1>> of t!e articles of anaggregate $e .it!in a secified sie range=
• ?educe as uc! reect as ossi$le fro a it in
order to efficientl use t!e aterial resources of a
it• Fsuall 5 ; 1> of t!e aggregate articles can $e
allo.ed to $e larger or saller t!an secs
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Highway Materials, Soils, and Concrete
Aggregates
• es of *ggregates
– Noinal Sie
• Coarse aggregates 19;4=75 noinal aggregate• Bine aggregate 4=75 noinal aggregate
– Clear
• a single sie coarse aggregate is called clear= @ost
of t!e articles are $et.een t!e secified a:iu
sie and a iniu sie .!ic! is defined as one;
!alf of t!e a:iu
• 19 clear aggregate
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Highway Materials, Soils, and Concrete
Aggregates• *ggregate -roerties
– ,radation (grain sie analsis)
• grain sie distri$ution for !ig!.a $ases and as!alti:es t!at .ill ro%ide a dense strong i:ture
• ensure t!at t!e %oids $et.een t!e larger articles are
filled .it! ediu articles= !e reaining %oids are
filled .it! still saller articles until t!e sallest %oids
are filled .it! a sall aount of fines=
• Ensure a:iu densit and strengt! using a
a:iu densit cur%e
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Highway Materials, Soils, and Concrete
Aggregates!eoretical @a:iu Densit Cur%es
• Buller @a:iu Densit Cur%e
- G (d/D)>=5 - G assing sie%e sie Hd" and HD" reresents
t!e a:iu sie%e sie (1>> assing)
• Bederal ig!.a *dinistration
- G (d/D)>=45
– lotted on sei;log aer .!ere sie%e sies are
raised to o.er >=45
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Highway Materials, Soils, and Concrete
Aggregates
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Highway Materials, Soils, and Concrete
Aggregate Gradations
• Strengt! or resistance to s!ear failure in road
$ases and a%eents is increased greatl if
t!e i:ture is dense graded
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Highway Materials, Soils, and Concrete
Aggregate Gradations
a) larger articles are in contact .it! eac! ot!er
de%eloing frictional resistances to s!earing failure=-articles are tig!tl $ond toget!er due to t!e inter;
loc&ing effect of saller articles= !is effect is
!ig!er in (a) t!an ($)
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Highway Materials, Soils, and Concrete
Aggregate Gradations $) @ust liit t!e aount of fines
– silt and cla articles are relati%el .ea&
– dust on larger aggregates .ill interface .it! t!e
aggregate/as!alt $ond – E:cessi%e fines in a $ase or su$$ase a lead to
drainage on frost lea%ing ro$les
– E:cessi%e fines (saller aggregates) results in .ea&
structures $ecause larger articles are not in contact
.it! eac! ot!er strengt!
– Sn (saller articles) are .ea&er= !erefore anaging
of fines is iortant=
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Highway Materials, Soils, and Concrete
AggregatesJas!ed Sie%e *nalsis• as a result it is iortant in deterining t!e aount
assing t!e 75µ sie%e
• sale is dried and .as!ed# .as! .ater oured out
o%er t!e 75 u sie%e
• aterial retained is returned to t!e sale for sie%e
analsis
• total aount assing 75 u is e
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Highway Materials, Soils, and Concrete
AggregatesE:ale 4;1@ass of sale 44=7 g
@ass after .as!ing 414=1 g
?esults of dr sie%ing8
?etained in 4=75 >=>g1=1 +>5=3g
3>> 1+7=9g
75 7=4g
-an 3=g
Bind t!e grain;sie distri$ution80ost in .as!ing o%er 75 G 44=7 g ; 414=1 gG 3+= g
-assing 75 in sie%ing 3= g
otal finer t!an 75 3=4 g
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Highway Materials, Soils, and Concrete
Aggregates
Note8 Anl >=7 g .as lost during sie%ing# .!ic! is anacceta$le loss=) If a .as!ed sie%e analsis is not
re
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Highway Materials, Soils, and Concrete
Aggregates
• *ggregate -roerties
– ,radation (grain sie analsis)• ig! densit i:tures are iortant in ters of
densit and as!alt ceent re
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Highway Materials, Soils, and Concrete
Aggregates• !e relati%e densit (secific gra%it) and
a$sortion of aggregates are iortant
roerties eseciall in as!alt ceenti:tures
– In t!e i: designs# it is iortant to easure
accuratel t!e %olues occuied $ t!e
aggregate and an .ater t!at a !a%e seeedinto t!e ores in t!e articles= !erefore %oids
ust $e considered in t!e aggregate=
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Highway Materials, Soils, and Concrete
Aggregates
• Bor aggregates
– Dr @ass G @D
– otal @ass G @SSD
• (dr ass @D K a$sor$ed .ater @J*)
– 2ul& Lolue G L2
• (includes %olue of a$sor$ed .ater) – Net Lolue G L N
• L N G L2 ; %olue of a$sor$ed .ater
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Highway Materials, Soils, and Concrete
Aggregates
• ?elati%e densit calculations are ade
as follo.s8
*arent ?D* G @D/(L N : ρJ)
2ul& ?D2 G @D/(L2 : ρJ)
Saturated# surface;dr ?DSSD G @SSD/(L2 :
ρJ)-ercentage a$sortion *$s G @J*/@D
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Highway Materials, Soils, and Concrete
Aggregates
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Highway Materials, Soils, and Concrete
Aggregates
•Saturated Surface Dr – all erea$le ores filled .it! .ater
2ul& Lolue G L NE4 K L*2SA?2ED J*4E?
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Highway Materials, Soils, and Concrete
Aggregatesis "8.4 g. $e net volume is 8!5.4 cm!. &ind te relative densit' values.
(ass o) a*sor*ed +ater "8.4 , !#.1 - #.! g
olume o) a*sor*ed +ater #.! g - #.! cm!
1 g/cm!
0ul olume 8!5.4 cm! 2 #.! cm! - 8"4.7 cm!
$ere)ore R3 - !#.1 g - ."8
8!5.4 cm! 1 g/cm!
R30 - !#.1 g - .5#
8"4.7 cm! 1 g/cm!
R3SS3 - "8.4 g - ."
8"4.7 cm! 1 g/cm!
% *s - #.! g - 1.!1%
!#.1 g
Example 4-2 $e dr' mass o) a sam6le is !#.1 g. $e mass in saturated sur)ace,
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Highway Materials, Soils, and Concrete
Aggregates
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Highway Materials, Soils, and Concrete
Aggregate Properties
• *ggregate ardness (resistant to .ear)
– It is iortant t!at aggregates for a%eent
surfaces not $ecoe rounded or olis!ed t!ere$
reducing s&id resistance
– 0oad ccles in t!e a%eent structure tend to
$rea& aggregates or fines .ill result c!anging t!e
gradation (finer) resulting in reduced strengt! oft!e a%eent structure
– 2ro&en aggregates are not ceented into t!e
structure# again reducing strengt!
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Highway Materials, Soils, and Concrete
Aggregate Properties
• *ggregate ardness (cont"d)
– ?esistance to degradation during i:ing#
transortation# lacing and coacting is iortant
as soft articles a $rea& c!anging t!e gradation
– 0os *ngeles *$rasion est easures t!e !ardness
of aggregates
– De%al *aratus – *ggregate Iact Lalue est
– -olis!ed Stone Lalue est
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Highway Materials, Soils, and Concrete
Aggregate Properties
• *ggregate Dura$ilit
– resistance to degradation due to ccles of .etting and
dring# !eating and cooling# and freeing and t!a.ing
– freeing and t!a.ing
• ore saces in t!e aggregate are often saturated and on
freeing e:ands
• reeated ccles can cause t!e aggregate to $rea&
• sedientar roc&s are %ulnera$le $ecause of lanes of
.ea&ness $et.een laers
– Soundness est Bield -erforance / *$sortion Lalue
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Highway Materials, Soils, and Concrete
Aggregate Properties
• *ggregate -article S!ae/Surface e:ture
– $onding caa$ilit .it! as!alt ceent
• articles .it! roug! fractured faces allo. a $etter $ond
.it! as!alt ceents t!an rounded soot! articles
– resistance to one article sliding o%er anot!er
– flat# t!in# long aggregate articles $rea& easier
t!an cu$ical articles
• Secifications restrict t!e ercentage of long t!in
articles and re
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Highway Materials, Soils, and Concrete
Aggregate Properties
• Deleterious Su$stances
– !arful or inurious aterials including %arious
tes of .ea& or lo.
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Highway Materials, Soils, and Concrete
Aggregate Properties
• *ggregate Crus!ing Strengt!
– crus!ing strengt! is t!e coressi%e load t!at
aggregate articles can carr $efore $rea&ing – relati%el uniortant for ost aggregates
strengt! is !ig!er t!an t!e strengt! of an as!alt
i:
• C!eical Sta$ilit
– refers to secific ro$les due to c!eical
coosition
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Highway Materials, Soils, and
Concrete Aggregate Specifications
– Secifications $ !ig!.a deartents ta&es
into account t!e aggregate roerties .e ust
discussed – ?e
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Highway Materials, Soils, and Concrete
Aggregate Properties
*$rasion test8
Ariginal ass 5>>9g 5>>9;3+7 G 34=
Binal ass 3+7 g 5>>9
Soundness test8
Ariginal ass +49g +49;+115 G +>=+
Binal ass +115 g +49
;lo.er strengt! fines content
;drainage and frost !ea%e otential
;dura$ilit
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Highway Materials, Soils, and Concrete
Aggregate Sampling and Testing
• !e c!aracteriation of an aggregate source
deends on !o. reresentati%e t!e sales are
ta&en fro t!e aggregates
– sie of sales are secified
– sales s!ould $e o$tained fro t!e final roduct
if ossi$le# after all t!e stes in rocessing andtransortation !a%e $een coleted
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Highway Materials, Soils, and Concrete
Aggregate Sampling and Testing
– Sales ta&en fro a roduction or disc!arge
s!ould $e ta&en at %arious ties and across t!e
entire cross section of disc!arge and co$ined to
for one sale
– Saling fro stoc&iles re
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Highway Materials, Soils, and Concrete
Aggregate Sampling and Testing
– Sales ta&en fro a truc& or rail.a car s!ould
$e done fro a cross sectional trenc!# t!ree
co$ined to for one sale
– Co$ined sales s!ould $e done .it! e
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Highway Materials, Soils, and Concrete
Aggregate Sampling and Testing
– Sales tested in t!e la$ ust $e reresentati%e of
t!e sales deli%ered to t!e la$
• Sale Slitting
– testing aggregates coosed of significant aounts
of $ot! coarse and fine aggregates t!e sale ust
$e slit on t!e 4=75 sie%e and t!e t.o fractions
sie%ed searatel – If not# t!e aount of sale on t!e fine sie%es a
$e too great for effecti%e sie%ing
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Highway Materials, Soils, and Concrete
Aggregate Sampling and Testing
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Highway Materials, Soils, and Concrete
Aggregate Sampling and Testing
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Highway Materials, Soils, and Concrete
Aggregate Sampling and Testing
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Highway Materials, Soils, and Concrete
Aggregate Sampling and Testing