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Asphalt Concrete Mix
DesignSuperpave
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Superpave Volumetric Mix Design
GoalsCompaction method which simulates fieldAccommodates large size aggregates
Measure of compactibilityAble to use in field labsAddress durability issues
Film thickness Environmental
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SHRP Project 1988 199!
he !utcomes of the S"#$ $ro%ect&ew Asphalt Grading system '$G(
Consensus properties of aggregates&ew Mi) *esign $rocedureMi)ture Analysis procedure 'AAMAS(
3
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Superpave Asphalt Binder
Specification
he grading system is based on Climate
$G +, - ..
$erformance
GradeAverage /-day ma)
pavement temperature
Min pavement
temperature
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$G ,+ $G 0. $G 01 $G +, $G /2 $G /+ $G 1.
'#otational 3iscosity( #3
42 42 522 522 522 '552( 522 '552( 552 '552(
'Flash $oint( F$
,+ 0. 01 +, /2 /+
,+ 0. 01 +, /2 /+
'#!667&G "7& F76M !3E&('#!667&G "7& F76M !3E&( #F!#F! Mass 6ossMass 6oss 88 5922 :5922 :
'*irect ension( *
';ending ;eam #heometer( ;;# $hysical "ardening
.1
-
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$G ,+ $G 0. $G 01 $G +, $G /2 $G /+ $G 1.
'#otational 3iscosity( #3
42 42 522 522 522 '552( 522 '552( 552 '552(
'Flash $oint( F$
,+ 0. 01 +, /2 /+
,+ 0. 01 +, /2 /+
'#!667&G "7& F76M !3E&('#!667&G "7& F76M !3E&( #F!#F! Mass 6ossMass 6oss 88 5922 :5922 :
'*irect ension( *
';ending ;eam #heometer( ;;# $hysical "ardening
.1
-
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Aggregate Properties
Coarse and fine aggregate angularity Flat and elongated particles
Sand euivalent results 'Clay content(
7
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Aggregate angularit"Aggregate angularit"
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Percent #racture$ #acesPercent #racture$ #aces
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Re%uirements #or angularit"
Coarse aggregates H based on traffic anddepth from surface
: of 5 or more fractured faces: of . or more fractured faces Fine aggregates H based on traffic and
depth from surface >n-compacted voids
10
100 sbWV G
V
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Re%uirements #or &lat an$ elongate$Re%uirements #or &lat an$ elongate$
particlesparticles
6ongest dimension'6( is compared to
the shortestdimension ';(9
7f 6D; ? 0= thenaggregate is flat or
elongated9
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San$ e%uivalent 'cla" content(San$ e%uivalent 'cla" content(
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Re%uirement #or san$ e%uivalent
raffic H ESA6 'Millions( Sand Euivalent 'Min :(
< 0.3 40
< 1 40
< 3 40
< 10 45
< 30 45
< 100 50
100 50
13
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)ther aggregate properties
6os Angeles Abrasion Sulphate soundness
Absorption
14
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Aggregate Si*e De#initions
+ominal Maximum AggregateSize
one size larger than the first sieve to
retain more than 52:
MaximumAggregate Sizeone size larger than nominal
ma)imum size
100100
1001009090
7272
6565
4848
3636
2222
1515
99
44
100100
99998989
7272
6565
4848
3636
2222
1515
99
44
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100100
00.075.075 .3.3 2.36 2.36 4.75 4.75 9.59.5 12.5 19.012.5 19.0
$ercent $assing$ercent $assing
control pointcontrol point
restricte$ *onerestricte$ *one
ma) density linema) density line
ma)ma)
sizesizenomnom
ma)ma)
sizesize
Sieve Size 'mm( #aised to 29,0 $owerSieve Size 'mm( #aised to 29,0 $ower
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Superpave Aggregate ,ra$ation
100100
00
.075.075.3.3 2.36 2.36 12.512.5 19.019.0
$ercent $assing$ercent $assing
Design Aggregate StructureDesign Aggregate Structure
Sieve Size 'mm( #aised to 29,0 $owerSieve Size 'mm( #aised to 29,0 $ower
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Superpave Mix Si*e Designations
SuperpaveSuperpave &om Ma) Size&om Ma) Size Ma) SizeMa) Size
*esignation*esignation 'mm( 'mm( 'mm( 'mm(
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Re%uirements #or Control points an$
Restricte$ -one .oun$ar" &ominal ma)imum size determines these
reuirements 'ables ,-+ to ,-52(
. H < trial gradations are used initially foran estimated optimum asphalt content9
he best blend based on min 3MA= &iand&ma)reuirements is selected for the mi)
design9
19
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Specimen Preparation
Mechanical mixer
0.170 Pa-s binder viscosity Short term oven aging
4 hours at 135!
" hours at 135! #o$tional%
&ging allo's absor$tion o(as$halt by aggregates
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.1.1
.2.2
.3.3
.5.5
11
1010
55
100100 110110 120120 130130 140140 150150 160160 170170 180180 190190 200200
)em$erature* !)em$erature* !
+iscosity* Pa s+iscosity* Pa s
Compaction Range
Mixing Range
Mixing/Compaction 0emps
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Specimen Preparation
Specimen "eight Mi) *esign - 550 mm ',/22 g(
Moisture Sens9 - 40 mm '
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Place pre-heated aggregate in bowland add hot aphalt
Mixing
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MixingPlace bo'l on mixer and mix until
aggregate is 'ell-coated
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,m$ty mix into $an and $lace in oven to
simulate short term aging
" hours (or lo' absor$tion aggregates
4 hours (or high absor$tion aggregates
Short 0erm Aging
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Short 0erm Aging mportant
Allows time for aggregate to absorb asphalt "elps minimize variability in volumetric
calculations
Most terms dependent upon volumes whichchange with changes in the amount
'volume( of absorbed asphalt
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Compaction
$lace funnel on top of mold and place mi) in mold9ake care not to allow the mi) to segregate9
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Compaction
$lace another paper on top of mi)
and place mold in compactor9
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E)ample of typical full-size compactors9
Compaction
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reaction
frame
rotating
base
loading
ram
control and data
acuisition panel
mold
height
measurement
tilt bar
2e" Components o# ,"rator" Compactor
Compaction
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Compaction
Gyratory compactor
A)ial and shearing action 502 mm diameter molds Aggregate size up to
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+um3er o# ,"rations '+(
*epends on ESA6s and Av9 *esign "igh Airemperature9
;e as &i= &dand &m9
&dis &-design and is the number of gyrations
reuired to produce density euivalent to fielddensity at ,: air voids9
32
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+um3er o# ,"rations '+(
&iis &-initial and is the number of gyrationsreuired to produce mi)tures with at least 55: air
voids9 his avoids tender mi)es9
&mis &-ma)imum and is the number of gyrationsreuired to produce mi)tures with a laboratory
density never achievable in the field '.: air voids(9
&iI '&d(29,0and &mI '&d(5952
33
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After aging= take mi) and preheated moldfrom oven9 $lace paper in bottom of mold9
Compaction
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!nce compaction is finished= e)trudesample from mold9
Compaction
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Compaction
#emove the paper and label samples9
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Densit" Determination
he bulk densities are determined at thedifferent levels of &9
hese are got both by computer'calculated( and measurement 'Actual(9 A correction factor 'CF( is then obtained I
Actual densityDcalculated density9
6oose samples of mi)tures are used todetermine the G
mm9
37
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Selection o# )ptimum AC
*etermine estimated opt AC using trialblends9
$repare specimens at 290: below !AC= at!AC= 290: and 592: above !AC9 Mi) each sample and oven age at 5
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Selection o# )ptimum AC
#emove from mold and determine Gmbat&m9
*etermine the CF and ad%ust air voids at &iand &d9
$lot $ercent Gmm I 522@'GmbDGmm(
#ecall &iI? 55: Avoids= &dI? ,: Avoidsand &
mI? .: Avoids
39
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S,C Results
mm
/og yrations
10 100 1000
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mmmm
/og yrations/og yrations
1010 100100 10001000
iniini
desdesmaxmax
0hree Points on S,CCurve
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Design Compaction
&desbased on
average design highair temp
traffic level
6og &ma)I 5952 6og &des 6og &iniI 29,0 6og &des
mm
/og yrations10 100 1000
ini
des
max
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umber o( yrationsumber o( yrations
44
22
00
""
44
22
100100
11 1010 100100 10001000
S$ecimen 1S$ecimen 1
S$ecimen "S$ecimen "
&verage&verage
mmmm
maxmax 174 174
desdes 10 10
iniini
Data Presentation
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Superpave Mix Design Anal"sis
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Superpave 0esting
Specimen heights Mi)ture volumetrics
Air voids 3oids in mineral aggregate '3MA( 3oids filled with asphalt '3FA( Mi)ture density characteristics
*ust proportion Moisture sensitivity
Superpave Mix Design
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Gmb'estimated( I m
Superpave Mix Design
!"#$
hereJ
mI mass of specimen= g3m)I volume of compaction mold 'cm
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"owever= surface irregularities cause the volume of the
specimen to be slightly less than volume of cylinder Actual bulk specific gravity measurement of compacted
sample used to determine correction factor= CJ
Superpave Mix Design
C IGmb'measured(
Gmb'estimated(
: GmmI Gmb'estimated( C D Gmm'measured(
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Superpave Mix Design
*etermine mi) properties at &*esignand compare tocriteria
Air voids ,: 'or 4+: Gmm(
3MA See table 3FA See table
:Gmmat &ini 8 14:
:Gmmat &ma) 8 41: *ust proportion 29+ to 59.
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S,C Results
: Gmm
6og Gyrations52 522 5222
ncreasing asphalt
cement content
Each line I avg9 of two samples
inides max
4+:
',: 3oids(
S Mi D i
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3MA reuirementsJ&ominal ma) agg size Min9 3MA
%490 mm 50
%5.90 mm 5,%54 mm 5