Performance Evaluation of Polymer Modified Asphalt Mix

7/25/2019 Performance Evaluation of Polymer Modified Asphalt Mix

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ABSTRACTAsphalt binder whose properties are modified by the addition of a polymer is

Polymer Modified asphalt.

Polymer is combination of a large number of similar small molecules or monomers

into large molecules. Polymers can be divided into two; Natural polymers and Synthetic

polymers. Natural polymers occur naturally in nature. Examples include hair rubber

diamonds and sulphur. Synthetic polymers are polymers that have been manufactured in a

chemical process to combine particular molecules in a way that would not occur naturally.

!he synthetic polymers are used in modifying asphalt. !he various polymers used to

modify asphalt include !hermoplastic "ubbers Styrene #utadiene Styrene Ethylene $inyl

Acetate Amorphous Polyalphaolefin %ellulose fiber Polyolefin #ituminous cellulose

fiber etc.

!he polymer additives do not chemically combine or change the chemical nature of

the asphalt being modified apart from being present in and throughout the asphalt. !he way

the additive&polymer usually influences the asphalt characteristics is by dissolving into

certain component fractions of the asphalt itself spreading out its long chain polymer

molecules to create an inter'connecting matrix of the polymer through the asphalt. (t is this

matrix of the long chain molecules of the added polymer that modifies the physical

properties of the bitumen. !he improved properties of the asphalt include lesser stiffness

greater wor)ability better strength coating capabilities etc.

!he polymers changes the physical nature of asphalt and modifies the physical

properties of the asphalt li)e softening point and brittleness of the asphalt. Elastic

recovery&ductility is also found to be improved. !his in turn will alter the properties of the

aggregate'bitumen mixture in which the modified bitumen is used. Pavement with polymer

modification exhibits greater resistance to rutting and thermal crac)ing and decreased

fatigue damage stripping and temperature susceptibility. Polymer modified binders have

been used with success at locations of high stress such as intersections of busy streets

airports vehicle weigh stations and race trac)s.

!his report aims in explaining the influence of polymer modified asphalt on rutting

and stripping of hot mix asphalt by reviewing various studies conducted in the past.

CONTENTS

*.(N!"+,-%!(+N *

*.*P+/ME" M+,(0(E, ASP1A! *

1


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*.2"-!!(N3 (N ASP1A! PA$EMEN!S 2*.4 S!"(PP(N3 (N ASP1A! PA$EMEN!S 4

2."-!!(N3 "ES(S!AN%E +0 P+/ME" M+,(0(E, ASP1A! M(5!-"ES 62.* (N!"+,-%!(+N 6

2.2 E5PE"(MEN!A S!-,/ %+N,-%!E, #/ S-"E//A !A/0-" E!. A (N 2778

8

2.2.* MA!E"(AS 8

2.2.2,E!E"M(NA!(+N +0 +P!(M-M ASP1A! %+N!EN! 9

2.2.4 PE"0+"MAN%E !ES!S :

2.2.4.* (N,("E%! !ENS(E S!"EN3!1 !ES! :

2.2.4.2 (N,("E%! !ENS(E !ES! *7

2.2.4.4 S!A!(% %"EEP !ES! *4

2.2.4.6 "EPEA!E, %"EEP !ES! *8

2.2.4.8 %P% "-!!(N3 !ES! *9

2.2.6 S-MMA"/ *

4. S!"(PP(N3 "ES(S!AN%E +0 P+/ME" M+,(0(E, ASP1A! M(5 2*4.* (N!"+,-%!(+N 2*

4.2 E5PE"(MEN!A S!-,/ %+N,-%!E, #/ %A3"( 3+"AS!M , *==6 ? "ES-!S 2

4.2.6.2 M+,(0(E, +!!MAN !ES! >AAS1!+ ! 2:4? "ES-!S 44

4.2.8 S-MMA"/ 4=

6. %+N%-S(+NS 4:

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"E0E"EN%ES 4

1. INTRODUCTION

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1.1 POLYMER MODIFIED ASPHALT

Asphalt binder whose properties are modified by the addition of a polymer is

Polymer Modified asphalt.

Polymer is combination of a large number of similar small molecules or monomers

into large molecules. !he polymer will have different properties than the monomer. !here

are a large number of naturally occurring polymers; these can be organic or mineral

substances. Such natural examples of polymers include hair rubber diamonds and sulphur.

Asphalt can also be regarded as a polymer because of the long'chain nature of some of the

organic molecules that are the constituent parts of asphalt. Synthetic polymers are polymers

that have been manufactured in a chemical process to combine particular molecules in a

way that would not occur naturally. !he synthetic polymers are used in modifying asphalt.

!he various polymers used to modify asphalt include !hermoplastic "ubbers Styrene

#utadiene Styrene Ethylene $inyl Acetate Amorphous Polyalphaolefin %ellulose fiber

Polyolefin #ituminous cellulose fiber etc.

!he polymer additives do not chemically combine or change the chemical nature of

the asphalt being modified apart from being present in and throughout the asphalt. !he way

the additive&polymer usually influences the asphalt characteristics is by dissolving into

certain component fractions of the asphalt itself spreading out its long chain polymer

molecules to create an inter'connecting matrix of the polymer through the asphalt. (t is this

matrix of the long chain molecules of the added polymer that modifies the physicalproperties of the bitumen. !he improved properties of the asphalt include lesser stiffness

greater wor)ability better strength coating capabilities etc. !he polymers changes the

physical nature of asphalt and modifies the physical properties of the asphalt li)e softening

point and brittleness of the asphalt. Elastic recovery&ductility is also found to be improved.

!his in turn will alter the properties of the aggregate'bitumen mixture in which the

modified asphalt is used. Pavement with polymer modification exhibits greater resistance to

rutting and thermal crac)ing and decreased fatigue damage stripping and temperature

susceptibility. Polymer modified binders have been used with success at locations of high

stress such as intersections of busy streets airports vehicle weigh stations and race trac)s.!his report aims in explaining the influence of polymer modified asphalt on rutting

and stripping of hot mix asphalt by reviewing various studies conducted in the past.

1.2 RUTTING IN ASPHALT PAVEMENTS

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"utting is surface depression in the wheel path. Pavement uplift >shearing? may

occur along the sides of the rut. "uts are particularly evident after a rain when they are

filled with water. !here are two basic types of rutting@ mix rutting and subgrade rutting.

Mix rutting occurs when the subgrade does not rut yet the pavement surface exhibits wheel

path depressions as a result of compaction&mix design problems. Subgrade rutting occurs

when the subgrade exhibits wheel path depressions due to loading. (n this case the

pavement settles into the subgrade ruts causing surface depressions in the wheel path. "uts

filled with water can cause vehicle hydroplaning can be haardous because ruts tend to pull

a vehicle towards the rut path as it is steered across the rut.

!he reason for rutting is permanent deformation in any of pavementBs layers or

subgrade usually caused by consolidation or lateral movement of the materials due to traffic

loading. Specific causes of rutting can be@

(nsufficient compaction of 1MA layers during construction. (f it is not

compacted enough initially 1MA pavement may continue to densify under

traffic loads.

Subgrade rutting >e.g. as a result of inadeCuate pavement structure?

(mproper mix design or manufacture >e.g. excessively high asphalt content

excessive mineral filler insufficient amount of angular aggregate particles?

Fig.1.1 Rutting in as!a"t a#$%$nts

S&u'($)***.t$!a%a(&unt+u,"i(*&'-s.(&%

1. STRIPPING IN ASPHALT PAVEMENTS

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!he loss of bond between aggregates and asphalt binder that typically begins at the

bottom of the 1MA layer and progresses upward is called stripping. Dhen stripping begins

at the surface and progresses downward it is usually called raveling.

Stripping decreases structural support and it also leads to rutting

shoving&corrugations raveling or crac)ing >alligatorand longitudinal?.#ottom'up stripping

is very difficult to recognie because it manifests itself on the pavement surface as other

forms of distress including rutting shoving&corrugations raveling or crac)ing. !ypically a

core must be ta)en to positively identify stripping as a pavement distress. !he reasons for

stripping are

Poor aggregate surface chemistry

Dater in the 1MA causingmoisture damage

+verlays over an existing open'graded surface course. !hese overlays will tend

to strip.

Fig.1.2 St'iing in as!a"t a#$%$nts

S&u'($)***.t$!a%a(&unt+u,"i(*&'-s.(&%

2.RUTTING RESISTANCE OF POLYMER MODIFIED ASPHALT MI/TURES

6
http://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#ravelinghttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#ruttinghttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#corrugationhttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#ravelinghttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#alligator_crackinghttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#alligator_crackinghttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#longitudinal_crackinghttp://training.ce.washington.edu/wsdot/modules/03_materials/03-2_body.htm#chemical_propertieshttp://training.ce.washington.edu/wsdot/modules/03_materials/03-3_body.htm#moisture_damagehttp://training.ce.washington.edu/wsdot/modules/03_materials/03-3_body.htm#moisture_damagehttp://training.ce.washington.edu/wsdot/modules/02_pavement_types/02-3_body.htm#open-gradedhttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#ruttinghttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#corrugationhttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#ravelinghttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#alligator_crackinghttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#longitudinal_crackinghttp://training.ce.washington.edu/wsdot/modules/03_materials/03-2_body.htm#chemical_propertieshttp://training.ce.washington.edu/wsdot/modules/03_materials/03-3_body.htm#moisture_damagehttp://training.ce.washington.edu/wsdot/modules/02_pavement_types/02-3_body.htm#open-gradedhttp://training.ce.washington.edu/wsdot/modules/09_pavement_evaluation/09-7_body.htm#raveling


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2.1 Int'&0u(ti&n

+ne of the most common forms of distress of asphalt concrete pavements is rutting

>permanent deformation?. "utting is the defined as the progressive accumulation of

permanent deformation of each layer of the pavement structure under repetitive loading.

!ests used to assess the resistance of bituminous mixes to flow rutting are mainly

the Marshall !est the static creep test the dynamic creep test the wheel trac)ing test and

the indirect tensile test. !hese tests are useful to compare alternative mix compositions

from a Cualitative point of view; in addition determination tests provide access to some

intrinsic mix properties which can be used in the theoretical and semi theoretical

performance models. !he implementation of a suitable test for assessing resistance to

accumulated permanent deformation under repeated loading which leads to wheel trac)

rutting is probably the most important reCuirement for performance'based specifications.

2.2 E/PERIMENTAL STUDY CONDUCTED BY SUREYYA TAYFUR $t. a" in 2

2.2.1 Mat$'ia"s

Asphalt and five different additives were used for the study. %oarse aggregate was

basalt and fine'filler aggregate was old calcareous. Some properties of asphalt used and

coarse and fine aggregate were given in !able 2.* and !able2.2.

Ta,"$ 2.1 P'&$'ti$s &3 As!a"t

!ES! ME!1+, -N(! $A-E

Specific gravity >287%? AS!M ,'97 g&cm4 *.726

0lash point >%leveland? AS!M ,'2 7% 477

Penetration >287%? AS!M ,'8 7.* mm =6

,uctility >287%? AS!M ,'**4 cm *77F

1eating loss'*=47% G 7.78

1eating loss Pen.&original

Pen. AS!M ,'8 G 89.:

,uctility after heating loss AS!M ,'**4 cm 8*.8F

Softening point AS!M ,'4= 7% 88

Source@ Sureyya !ayfur et. al 2778

Ta,"$ 2.2 P'&$'ti$s &3 (&a's$ an0 3in$ agg'$gat$s

P"+PE"!(ES !ES! ME!1+, $A-E

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%oarse aggregate

.A abrasion >G? AS!M %'*4* *4

Soundness in NaS+6>G? AS!M %':: 6.69

0la)iness >G? #S*:2 >Part *78? *7.:

Stripping resistance >G? AS!M ,'*==6 =7'97

Dater absorption >G? AS!M %'*29 7.:=

Polishing value #S':*4 7.=

0ine aggregate

Plasticity index Non'plastic


0ive different additives were used. !hese additives are amorphous polialfaolefin

>AP? cellulosed fiber >SE? cellulosed fiber mixed with bitumen >#E? poliolefin >PE? and

stiren'butadien'stiren copolymer >S#?.

AP ta)es parts in plastomer group. (t has a granular type and directly added to the

mixture in mixer. (t is added about percent 8H9 of bitumen weight. AP was added =G of

bitumen weight. Penetration value was *=H22 while softening point was :H**77% and

viscosity was 8777H*2777 MPa. SE was added 7.6G of mineral aggregate weight. (t was

added directly mixer in plant. #E was added 7.=G of total mixture weight. i)e SE #E

was added directly mixer in plant. PE was used in the mixture between percent 7.6G and

*G. PE was used 7.=G of total aggregate weight. S# additive can be mixed between 4G

and 9G of bitumen weight. S# was added to bitumen 8G. All additives were dispersed

homogeneously in the mixture. 3radation values of the aggregate are given in !able 2.4and

gradation curve are represented in 0ig.2.*.

Ta,"$ 2. G'a0ati&n in t!is stu0+ an0 "i%itsS(E$E S(E$E>mm? PASS(N3 >G? +DE"'-PPE" (M(!S

*&2 in. *2.9 *77 *77

4&: in. .82 92.8 =8 to :7

No.6 6.9= 47 28 to 48

No.*7 2 2*.8 *: to 28

No.67 7.62 *8 *2 to *:

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No.:7 7.**9 **.8 to *6

No.277 7.796 *7 : to *2


Fig.2.1 Agg'$gat$ 0ist'i,uti&n &n g'a0ati&n (!a't


2.2.2D$t$'%inati&n &3 Oti%u% As!a"t (&nt$nt

Marshall method >AS!M ,*88? was used for determining optimal bitumen

content for conventional and modified asphalt mixtures. !hree identical samples were

produced for all alternatives. #itumen range region was regulated according to the bitumen

demand for each mixture. Six designs were realied and *7: asphalt briCuettes were

fabricated. %ompacting energy was applied as 87 blows. !he results of Marshall !est are

shown in !able 2.6.

Ta,"$ 2.4 Ma's!a"" 0$sign '$su"ts

P"+PE"!/ N" AP SE PE #E S#

Asphalt >G? 8.= =.*4 =.: =.8 =.= =.=

Stability >)g? =98 =87 =8 947 =7 =7

#ul) specific gravity >g&cm4? 2.696 2.692 2.66 2.68 2.6=: 2.68:

$oid content >G? 6.2 6.* 4. 6.6 4.= 4.:

0low >mm? 4.* 4 6.48 4.=8 4 4.

$oid filled asphalt >G? 98 9= 9 9= 9 9

Maximum specific gravity>g&cm4? 2.8:4 2.899 2.86= 2.8=6 2.8= 2.889

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$oids filled mineral aggregate >G? *=.8 *9.2 *:.= *:.*6 *9.=6 *:


As it shown in !able 2.6optimum bitumen content has been increasing for modified

mixtures. SE mixture has the highest bitumen content. Stability values for modified

mixtures has been increasing for SE PE #E and S# mixtures but decreasing for AP

mixtures. Marshall flows were increased for SE PE S# mixtures but decreased AP and #E

mixtures. $oids filled with binder and voids filled with mineral aggregate values for

modified mixtures were increased. !he highest optimal bitumen content obtained from

Marshall !est was found in mixture with the cellulose fiber. !his was an expecting result

because of wise specific surface area and highly bitumen demand of cellulose fibers. $oid

in mineral aggregate reached *9G for all mixtures.

2.2. P$'3&'%an($ t$sts

%onventional and modified mixtures were evaluated with the indirect tension

strength test indirect tension test static creep test repeated creep test and %P% rutting

test. !ests were realied at optimum asphalt content for all mixtures.

2.2.3.1 Indirect tensile strength test

!he indirect tensile strength test was used to determine the tensile properties of the

asphalt concrete which can be further related to the crac)ing properties of the pavement. (n

this test a compressive load was applied along a diametrical plane through two opposite

loading strips. !his type of loading produced a relatively uniform tensile stress which acts

perpendicular to the applied load plane and the specimen usually fails by splitting along

the loaded plane.

!est was simple and Marshall Specimens were used. Surface irregularities do not

seriously affect the results and the coefficient of the variation of the test results was low.

!his test was applied at 287% on briCuettes both on conventional mixture and modified

ones. ,uration of the test load and deformation values was saved until brea)ing point.

Poisson ratio was used as 7.48 and calculated horiontal deformations. $ariation of indirect

tension strengths of the mixtures were illustrated in 0ig.2.2.

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Fig.2.2 In0i'$(t t$nsi&n st'$ngt! &3 t!$ %i5tu'$s


!he typical values of the indirect tensile strength of specimens >*: Marshall

Specimens? obtained ranged from =:4 to *9 )Pa. Modified mixtures showed an increase

in the tensile strength at 287%. PE and S# modified mixtures gave the highest strengths.

!he use of low density polyethylene >plastiphalt? as bitumen modifier has been

investigated and the results showed that an improvement in the Cuality of the binder and

mix properties. !he indirect tensile strength values were found to be much higher. A higher

tensile strength corresponds to a stronger low temperature crac)ing resistance.

!he indirect tensile strengths of the modified mixtures were also higher than the

control mix. !his indicated that the mixtures containing additives have higher values of

tensile strength at failure indirect tensile strength under static loading. !his would further

imply that modified mixtures appear to be capable of withstanding larger tensile strains

prior to crac)ing. %onventional dense graded mixes normally combine high stability with

low flow values and hence high MI values indicating a high stiffness mix with a greater

ability to spread the applied load and resist creep deformation. %are must be exercised with

very high stiffness mixes due to their lower tensile strain capacity to failure i.e. such

mixes are more li)ely to fail by crac)ing particularly when laid over foundations which fail

to provide adeCuate support. Although the Marshall stability of the plastiphalt mix was

much higher than the control mix the flow values of plastiphalt mixes was also greater

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indicating higher strain capacities to achieve failure. !he value of MI of the plastiphalt

was higher than of the control mix. (t was well recognied that the MI is a measure of the

materials resistance to shear stresses permanent deformation and hence rutting.

2.2.3.2 Indirect tensile test

"esilient modulus of asphalt mixtures measured in the indirect tensile mode

>AS!M ,6*24? was the most popular form of stressHstrain measurement used to evaluate

elastic properties. !he resiliency modulus along with other information was then used as

input to the elastic theories model to generate an optimum thic)ness design. !herefore the

effectiveness of the thic)ness design procedure was directly related to the accuracy and

precision in measuring the resiliency modulus of the asphalt mixture. !he accuracy and

precision were also important in areas where resilient modulus is used as an index for

evaluating stripping fatigue and low temperature crac)ing of asphalt mixtures. (ndirect

tensile tests were applied for both conventional and modified mixtures. $ariations of

temperatures in the experiments were used as 8 28 and 677%. Applied load was *877 N that

this load was nearly 27G of the indirect tensile strength test at 28 7%. $ariation of the

experiment parameters were shown in !able 2.8.

Ta,"$ 2. L&a0ing (&n0iti&ns &3 t!$ t$st

+A,(N3 PE"(+,"(SE !(ME >ms?

0"EI-EN%/ >1? P-SE PE"(+, >ms?

7.44 4777 67=7:7

7.8 2777 67=7:7

* *777 67=7:7


Pulse time was chosen *777 ms for high traffic)ed roads volume roads and 4777 ms

for low traffic)ed volume roads. Also vehicle speeds were observed and 67 ms rise time for

high speed and :7 ms rise time for low speed were used. !he average results of the resilient

modulus are shown in 0ig.2.4.

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Fig.2. A#$'ag$ '$si"i$nt %&0u"us 3&' a"" %i5tu'$s


Each value was obtained as 86 different resilient modulus ratios. Elasticity modulus

values were the highest at 8 and lowest at 677%. !hese values were suitable with the

viscoelastic behavior.

"esilient modulus values for mixtures were presented in 0igs.2.6 2.8 and 2.=.

Average values were used for three identical briCuettes for same mixture.

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Fig.2.4 R$si"i$nt %&0u"us 3&' (&n#$nti&na" an0 %&0i3i$0 %i5tu'$s6C7


Fig.2. R$si"i$nt %&0u"us 3&' (&n#$nti&na" an0 %&0i3i$0 %i5tu'$s62C7


Fig.2.8 R$si"i$nt %&0u"us 3&' (&n#$nti&na" an0 %&0i3i$0 %i5tu'$s64C7


14


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Dhile lower modulus values were obtained at low temperature >87%? higher

modulus values were obtained at high temperature >677%? for modified mixtures. 1ence

modified mixtures showed more low temperature crac)ing and rutting performance.

According to the indirect tension test conventional mixtures had higher elasticity

modulus as 48G at 87% that is that mixtures had the lowest crac)ing resistance. Pulse time

changing >traffic density? increased elasticity modulus as much as :G for all temperatures

while rise time >traffic speed? increased 28G especially at 28 and 677%.(ndirect tensile

stiffness modulus values tend to converge at 67 and =77% for control and modified asphalt

mixtures. 0ig.2.4shows the summaried indirect tensile stiffness modulus results for both

the modified and control mixtures at 8 28 677%. !he results indicated that the stiffness

modulus values of the control mixtures especially at 8 7% are higher than the modified

mixtures but that at higher temperatures >28677%? the values tend to converge also.

2.2.3.3 Static creep test

!est were done to determine permanent deformation of asphalt mixtures. %reep

deformation of a cylindrical specimen under a uniaxial static load was measured as a

function of time the sample dimensions and test conditions were standardied.

,eformation values were measured with time by a linear variable transformer >$,!?. !est

was carried out for all mixtures at the dosage of optimal bitumen. #ecause the permanent

deformation ris) was more under the heavy load and high temperature test parameters were

selected@ uniaxial load was 628 7.6 MPa? temperatures were 28 and 67 7% load

duration was 4=77 s. !he values of static creep compliance obtained from the test are given

in 0igs.2.9 and 2.:.

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Fig.2.9 Ti%$ #$'sus 0$3&'%ati&n in stati( ('$$ t$st 62C7


Fig.2.: Ti%$ #$'sus 0$3&'%ati&n in stati( ('$$ t$st 64C7


$alues were thought according to the SMA mixtures that had high creep modulus.

!he performance of SMA flexible pavements can be considerably be improved by using

premium bituminous binders as prepared by modification. !he rutting calculation model in

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the present method did not correctly predict the improvements in rutting behaviour with

premium binders. !he repeated creep and %P% rutting test showed that S#S modified

mixtures had higher performance than the others. !here are controversial results in view of

the static creep tests especially for high >677%? temperature as it shown in 0igs.2.9 and 2.:.

1ence it has been suggested that static creep test does not reflect the performance of

modifiers which improve the elastic recovery of a materials as well as repeated loading

conditions.

2.2.3.4 Repeated creep test

Strength of the bituminous mixtures to the plastic deformation was determined with

the repeated creep test. !est eCuipment was the same as the static creep test but repeated

load were carried out differently. Efficiency of some selected chemical additives were

evaluated with the repeated creep test also rutting investigation of modified mixtures were

done. Experiments were done at 28 and 677

% test temperatures during *777 ms pulse

period. Samples were exposed to 9:7 N >*77 *4:

=7 7%? repeated creep test

failed because of the sample destruction. Misleading results were obtained. !ests were

realied at 28and 677%. 0igs.2. and 2.*7 shows the repeated creep curves. S# modified

mixtures showed best result.

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Fig.2.; Nu%,$' &3 (+("$s #$'sus $'%an$nt 0$3&'%ati&n62C7


Fig.2.1 Nu%,$' &3 (+("$s #$'sus $'%an$nt 0$3&'%ati&n64C7


2.2.3.5 LCPC Rutting test

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"utting !est was verified with the %P% method. !his test was capable of

simultaneously testing two 1MA slabs. Slab dimensions are typically *:7 mm wide 877

mm long and 27H*77 mm thic). "esearch indicates good correlation between %P% test

results and actual field performance.

Samples were prepared at 877 mm length *:7mm width and *77 mm height. !est

temperature was =77%. Samples were )ept at least *2 h at that temperature. Each type was

applied 8777 N load. !yre pressure was 7.= MPa >:9 psi?. Samples were compacted at a

determined degree of compacting. !est briCuettes were compacted at :G field compacting

scale. #efore the temperature was reached at =7 7% pre'compacting >*777 cycle? was done.

Pre'conditioning temperature was regulated and values were saved. After the values were

saved rutting was calculated. !wo identical samples were used for each alternative >see

0ig.2.**?.

Fig.2.11 As!a"t %i5tu'$ s"a,s a3t$' t!$ LCPC 'utting t$st


%P% rutting test results for conventional and modified mixtures are shown in 0ig.2.*2.

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Fig.2.12 LCPC *!$$" t'a(-ing t$st '$su"ts

Source@ Sureyya !ayfur et. al 2778S#S mixtures show the highest resistance to the permanent deformation and good

results are obtained with the repeated creep tests.(n the study optimum asphalt contents for

modified mixtures are higher than the conventional mixture. Modified mixtures reveal

more resistance to the permanent deformation in %P% wheel trac)ing test at =77%. (t is

believed by them that modifiers contribute to adhesion ability to deformation resistance.

2.2.4 Su%%a'+

!he conclusions obtained by reviewing the study are@

!he indirect tensile strengths of the modified mixtures were higher than the control

mix. !his indicated that the mixtures containing additives have higher values of

tensile strength at failure. !his further implyed that modified mixtures appear to be

capable of withstanding larger tensile strains prior to crac)ing >internal resistance?.

Marshall stability values of modified mixes were found to be higher than the controlmixtures. +nly AP mixture gave lower stability. AP and #E mixtures had lower

flow value.

According to the indirect tension test conventional mixtures had higher elasticity

modulus as 48G at 87% that is that mixtures had the lowest crac)ing resistance.

Pulse time changing >traffic density? increased elasticity modulus as much as :G for

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all temperatures while rise time >traffic speed? increased 28G especially at 28 and

677%. Stiffness modulus values of the control mixtures especially at 8 7% are higher

than the modified mixtures but that at higher temperatures >28 677%? the values

tend to converge.

Static creep test does not reflect the performance of modifiers which improve the

elastic recovery of a materials as well as repeated loading conditions.

S#S mixtures showed the highest resistance to the permanent deformation shownby repeated creep tests.

+ptimum asphalt contents for modified mixtures are higher than the conventional

mixture. Modified mixtures reveal more resistance to the permanent deformation in

%P% wheel trac)ing test at =77%. Modifiers contribute much to adhesion ability

among aggregates of hot asphalt mixtures.

!he type of asphalt modifier does significantly affect the permanent deformation

performance.

. STRIPPING RESISTANCE OF POLYMER MODIFIED ASPHALT MI/

.1 Int'&0u(ti&n

21


22/39

Environmental factors such as temperature air and water can have a profound

effect on the durability of asphalt concrete mixtures. (n mild climatic conditions where

good'Cuality aggregates and asphalt cement are available the maJor contribution to the

deterioration may be traffic loading and the resultant distress manifests as fatigue crac)ing

rutting >permanent deformation? and raveling. 1owever when a severe climate is in

Cuestion these stresses increase with poor materials under inadeCuate control with traffic

as well as with water which are )ey elements in the degradation of asphalt concrete

pavements. Dater causes loss of adhesion at the bitumenHaggregate interface. !his

premature failure of adhesion is commonly referred to as stripping in asphalt concrete

pavements. !he strength is impaired since the mixtureceases to act as a coherent structural

unit. oss of adhesion renders cohesive resistance of the interstitial bitumen body useless.

Dater may enter the interface through diffusion across bitumen films and access directly in

partially coated aggregate. Dater can cause stripping in five different mechanisms such as

detachment displacement spontaneous emulsification pore pressure and hydraulic scour.

Many variables affect the amount of moisture damage which occurs in an asphalt

concrete mixture. Some of these variables are related to the materials forming hot mix

asphalt >1MA? such as aggregate >physical characteristics composition dust and clay

coatings? and bitumen >chemical composition grade hardness crude source and refining

process?. +thers are related to mixture design and construction >air void level film

thic)ness permeability and drainage? environmental factors >temperature pavement age

freeeHthaw cycles and presence of ions in the water? traffic conditions and type and

properties of the additives.

Anti'stripping additives are used to increase physico'chemical bond between the

bitumen and aggregate and to improve wetting by lowering the surface tension of the

bitumen. !he additives that are used in practice are@ >i? traditional liCuid additives >ii?

metal ion surfactants >iii? hydrated lime and Cuic) lime >iv? silane coupling agents and >v?

silicone.

Methods of treatment to reduce moisture damage also include the utiliation ofpolymer modified bitumen >PM#?. Polymer is a derived word meaning many parts.

Polymers are made up of many smaller chemicals >monomers? Joint together end'on'end.

!he physical and chemical properties of a polymer depend on the nature of the individual

molecular units the number of them in each polymer chain and their combination with

other molecular types.

22


23/39

!wo basic types of polymers are used in modified bitumen of road applications@ >i?

elastomers and >ii? plastomers.

S#S >Styrene butadiene styrene? bloc) copolymers are classified as elastomers that

increase the elasticity of bitumen and they are probably the most appropriate polymers for

bitumen modification. Although low temperature flexibility is increased it is found that a

decrease in strength and resistance to penetration is observed at higher temperatures.

S#S copolymers derive their strength and elasticity from physical and cross lin)ing

of the molecules into a three'dimensional networ). !he polystyrene end bloc)s impart the

strength to the polymer while the polybutadiene rubbery matrix bloc)s give the material its

exceptional viscosity.

E$A>Ethylene vinyl acetate? based polymers are classified as plastomer that modify

bitumen by forming a tough rigid three'dimensional networ) to resist deformation. !heir

characteristics lie between those of low density polyethylene semi rigid translucent

product and those of a transparent and rubbery material similar to plasticied P$% and

certain types of rubbers.

#oth S#S and E$A type polymers are usually provided in the form of pellets or

powder which can be subseCuently diluted to the reCuired polymer content by blending

with base bitumen by means of low to high shear mixer. #lending pellets of with base

bitumen results in a special polymer concentration suitable for different applications.

Although the utiliation of PM#s for controlling the moisture damage is limited there is

evidence that some polymers can act as anti'stripping agents.

.2 E/PERIMENTAL STUDY CONDUCTED BY CAGRI GOR


24/39

Softening point > 7%? AS!M ,4= EN *629 6 6= to 86

$iscosity at >*48 7%?'Pa.s AS!M ,6672 7.8*

!hin film oven test >!0+!?>*=47%;8h? AS!M ,*984 EN *2=79'*

%hange of mass >G? 7.79 7.8 >max?

"etained penetration >G? AS!M ,8 EN *62= 8* 87 >min?

Softening point after !0+! >7%? AS!M ,4= EN *629 8* 6: >min?

,uctility >287%?'cm AS!M , **4 *77

Specific gravity AS!M ,97 *.74

0lash point >7%? AS!M ,2 EN 2282 2=7 247 >min?

Source@%agri 3or)em et al. 277

!wo types of aggregates were utilied for producing the asphalt mixtures@

imestone aggregate >as coarse fine and filler fraction? constitute the first type; whereas

basalt aggregate >substituting the coarse fraction of limestone aggregate? constitute the

second type aggregate. (n order to find out the properties of the aggregate used in this study

specific gravity os Angeles abrasion resistance sodium sulfate soundness fine aggregateangularity and flat and elongated particles tests were conducted on both aggregate types.

!he results are presented in !able 4.2.

Ta,"$ .2 P'&$'ti$s &3 "i%$st&n$ an0 ,asa"t agg'$gat$

!ES! SPE%(0(%A!(+N "ES-!SPE%(0(%A!('

+N (M(!

(MES!+NE #ASA!

Specific gravity >coarse

agg.?AS!M % *29

#ul) 2.=:= 2.===

SS, 2.97* 2.:*

Apparent 2.929 2.97=

24


25/39

Specific gravity >fineagg.?

AS!M % *2:

#ul) 2.=:9 2.=82

SS, 2.974 2.99

Apparent 2.942 2.=::

Specific gravity >filler? 2.928 2.94*

os angeles abrasion

>G?AS!M % *4* 26.6 *6.2 Max 68

0lat and elongated

particles >G?AS!M , 69* 9.8 8.8 Max *7

Sodium sulfate

soundness >G?AS!M % :: *.69 2.= Max *7'27

0ine aggregate

angularityAS!M % *282 69.:8 8:.* Min 67


!ables 4.4 and 4.6present the final gradation chosen for limestone and basaltHlimestoneaggregate mixture.

Ta,"$ . G'a0ati&n &3 "i%$st&n$

!ES! 3"A,A!(+N >G? SPE%(0(%A!(+N

SPE%(0(%A!(+N

(M(!S3"A,A!(+N AS!M % *4=

4&6K *77 *77

*&2K 7.8 :4 to *77

4&:K :7.8 97 to 7

No 6 69.4 67 to 88

No *7 44 28 to 4:

No 67 *4.8 *7 to 27

No :7 = to *8

No 277 8.4 6 to *7


Ta,"$ .4 G'a0ati&n &3 ,asa"t="i%$st&n$ agg'$gat$ %i5tu'$

!ES! *'*2.8 mm >#asalt? *2.8'8 mm >#asalt? 8'7 mm >imestone? %+M#(NE

Mixture ratio >G? *8 68 67

25


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3"A,A!(+N

4&6K *77 *77 *77

*&2K 48.9 *77 *77

4&:K 2.8 : *77

No 6 7.6 *= *77

No *7 7.4 *.2 :*

No 67 7.2 7.9 44

No :7 7.*8 7.6 22No 277 7.* 7.2 *4


!he elastomeric type polymer used was S#S 4*G? and polybutadiene of a very precise molecular weight. !hese bloc)s are either

seCuentially polymeried from styrene and butadiene and&or coupled to produce a mixture

of these chained bloc)s.

!he plastomeric type of polymer used was E$A supplied in pellet form which

contains vinyl acetate content of 29H2G is a highly flexible plastomer designed for

bitumen modification and especially for road paving.

.2.2 P'$a'ati&n &3 SBS> EVA %&0i3i$0 ,itu%$n

!he S#S and E$A modified bitumen samples were prepared by means of a high and

a low shear laboratory type mixer rotating at **77 rpm and *28 rpm respectively. (npreparation the base bitumen was heated to fluid condition >*:7H*:87%? and poured into a

2777 ml spherical flas). !he S#S and E$A polymers were then added slowly to the base

bitumen.

!he S#S concentrations in the base bitumen were chosen as 2H=G. !he content was

selected based on past research which concluded that improvement in the properties of base

bitumen was observed when the S#S content was increased from 2H=G by weight. !he

E$A concentrations on the other hand were chosen as 4H9G according to the

manufacturers.

+n reaching *:87% the temperature was )ept constant and the mixing process

continued for two hours. !he uniformity of dispersion of S#S and E$A in the base bitumen

was confirmed by passing the mixture through an AS!M *77L sieve. After completion the

samples were removed from the flas) and divided into small containers covered with

26


27/39

aluminum foil and stored for testing. !he conventional properties of the S#S and E$A

based PM# are presented in !able 4.8.

Ta,"$ . P'&$'ti$s &3 SBS an0 EVA PMB

P"+PE"!/ !/PE%+N!EN!

7 2 4 6 8 = 9

Penetration >*&*7 mm? S#S =4 =* 8* 6 6: 6:

Softening point > %? 6 87 86 89 =9 =

Penetration index >P(?

'

7.2

'

7.94

'

7.*= 7.48 2.*: 2.6=

%hange of mass >G? 7.79 7.7= 7.7= 7.79 7.79 7.79

"etained penetration after !0+! >G? 8* 6* 4* 26 2* 2*

Softening point difference after !0+!> %? 2 6 6 2 4 2

Storage stability > %? 4 4 2 4 2

Penetration >*&*7 mm? E$A =4 84 82 6 6: 69

Softening point > %? 6 86 89 8 =* =2

Penetration index >P(?

'

7.2

'

7.*4 7.6 7.9 *.*6 *.26

%hange of mass >G? 7.79 7.76 7.7= 7.78 7.79 7.7=

"etained penetration after !0+! >G? 8* 47 4* 42 44 46

Softening point difference after !0+!

> %? 2 = = 8 6 8

Storage stability > %? * * 7 * 2


.2. T$st %$t!&0s

0ollowing the determination of the properties of the materials used in this study and

the preparation of the samples the Nicholson stripping test and the modified ottman test

were conducted on loose mixtures and compacted samples respectively.

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3.2.3.1 Nicholson stripping test

AS!M ,*==6 !est Method for %oating and Stripping !est of #itumen Aggregate

Mixture was used to evaluate the degree of stripping of asphalt mixtures. (n this method

coarse aggregate >.8H=.4 mm? of both basalt and limestone was coated with PM#. !he

loose mixture was then immersed in distilled water for 26 h and the degree of stripping was

observed under water to visually estimate the total surface area of the aggregate on which

bitumen coating remains.

3.2.3.2 AASH! 2"3# standard $ethod o% test %or resistance o% co$pacted hot $i&

asphalt 'H(A) to $oisture induced da$age

!he modified ottman test was performed on the compacted samples including two

types of aggregate >basaltHlimestone mixture and limestone?. !he samples were prepared

with the S#S and the E$A based PM3. !he optimum bitumen content was determined as

6.:2G >by weight of aggregate? for mixtures prepared with S#S and E$A PM#.

!he aim of the modified ottman !est was to evaluate susceptibility characteristics

of the mixture to water damage. !his test was performed by compacting specimens to an air

void level of 9G O *.7. !hree specimen are selected as dry >unconditioned? and tested

without moisture conditioning; and three more were selected to be conditioned by

saturating with water >88H:7G saturation level? followed by a freee cycle >'*:7% for *= h?

and subseCuently having a warm'water soa)ing cycle >=77% water bath for 26 h?. !he

specimens are tested for indirect tensile strength >(!S? by loading the specimens at a

constant rate >87 mm&min vertical deformation at 287%? and the force reCuired to brea) the

specimen was measured. Moisture susceptibility of the compacted specimens was evaluated

by tensile strength ratio >!S"? which is calculated by following eCuation@

where S* is the average indirect tensile stress of dry >unconditioned? specimens and S2 is

the average indirect tensile stress of conditioned specimens. Specimens were sorted into

two subsets >both dry and conditioned? of three specimens each so that average air voids

>9G? of two subsets are eCual. !he design parameters related to modified ottman test arepresented in !able 4.=.

28


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Ta,"$ .8 D$sign a'a%$t$'s

!/PE +0 #(!-MEN A% 87&97 PENE!"A!(+N 3"A,E

!ype of aggregate !wo types aggregate

#asalt'limestone aggregate

mixture

imestone aggregate

!ype of additive and content !wo types of additive

S#S>2'=G?

E$A>4'9G?

!arget air void level >G? 9

!est performed (ndirect tensile strength at 287%

!otal number of specimens tested 0ive different S#S concentration two types of aggregate >basalt

limestone? 2 >dry and cond.? three

replicates Q=7

0ive different E$A concentration

two types of aggregate >basalt

limestone? 2 >dry and cond.? three

replicates Q=7


.2.4 R$su"ts an0 0is(ussi&n

3.2.4.1 Nicholson stripping test 'AS( * 1++4 ) results

!he visually inspected results of the prepared samples are presented in !able 4.9

29


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Ta,"$ .9 Visua" st'iing '$sistan($ &3 ,asa"t an0 "i%$st&n$ agg'$gat$

A,,(!($E %+N!EN! (MES!+NE #ASA!

S#S 7 87'88 48'67

2 88'=7 67'68 4 97'98 88'=7

6 98':7 =7'=8

8 :7':8 97'98

= :7':8 97'98

E$A 7 87'88 48'67

4 =8'97 67'68

6 97'98 67'68

8 98':7 68'87

= 98':7 68'87

9 98':7 68'87Source@%agri 3or)em et al. 277

As presented in !able 4.9 among the unmodified samples >with no polymer? the

level of coating related to limestone and basalt aggregate lies between 87H88 and 48H67

respectively. !his indicated that basalt aggregate exhibits more stripping potential

compared to limestone aggregate. !he reason for this pattern is the hydrophilic >attracting

water? character of basalt type aggregate that has a higher affinity to form hydrogen

bonding with water and conseCuently promotes stripping.

!he resistance to stripping increases with increasing polymer content for both

aggregate types as presented in !able 4.9. #esides no significant stripping variation is

observed in the values on reaching the S#S and E$A polymer contents of 8G.

Among the samples prepared with basalt aggregate a clear distinction regarding to

the degree of stripping was observed between S#S and E$A modified samples as seen in

!able 4.9. #ased on the basalt aggregate mixture prepared with 6G polymer content the

mixture involving E$A polymer exhibits more moisture susceptibility compared to the

mixture involving S#S polymer.

!he samples were also examined at room temperature under eica S:AP7 stereo

microscope after Nicholson stripping test. (mages were ta)en by a 9.2 Mp eica ,0% 427

color camera >fitted in line with the optic axis of the microscope by means of attachment?.

30


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!he camera digities the image and stores the data as an image file in the permanent

memory of the wor)station. 0igs.4.* and 4.2present the examples of the samples captured

by using digital camera.

Fig..1 A00iti#$s *it! ,asa"t agg'$gat$ sa%"$s (atu'$0 ,+ st$'$& %i('&s(&$


31


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Fig..2 A00iti#$s *it! "i%$st&n$ agg'$gat$ sa%"$s (atu'$0 ,+ st$'$&

%i('&s(&$


A distinction can be made between the basalt and limestone aggregate for all

samples. !his indicates that the adhesion between aggregate and asphalt in 1MA prepared

using limestone aggregate is higher than that of mixes prepared using basalt aggregate. (n

32


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other words the 1MA prepared using limestone aggregate have higher resistance to

stripping since the bond strength between asphalt and limestone aggregate is stronger than

that between asphalt and basalt aggregate.

As indicated in 0igs. 4.* and 4.2 the images show a clear variation in the level of

coating on basalt and limestone aggregate as the polymer content increases. #esides based

on the same type of aggregate and polymer content the difference in the level of coating

can be observed between the S#S and E$A polymer. !he mixture with E$A polymer

exhibits more stripping potential compared to the mixture with S#S polymer. (t is possible

to consider that for evaluating the stripping potential of the aggregates same trends are

achieved from captured images as well as from Nicholson stripping test.

3.2.4.2 (odi%ied Lott$an test 'AASH! 2"3) results

!he (!S test results of the specimens involving S#S E$A polymer and hydrated

lime are given in !able 4.:.

Ta,"$ .: In0i'$(t t$nsi"$ st'$ngt! t$st '$su"ts &3 t!$ (&%a(t$0 sa%"$s

A,,

(!($

E

%+N!EN!

>G?

(MES!+NE A33"E3A!E

#ASA!'(MES!+NE

A33"E3A!E

-N%+N,(!(+

NE, >)Pa?

%+N,(!(+NE,

>)Pa?

-N%+N,(!(

+NE, >)Pa?

%+N,(!(+NE

, >)Pa?

S#S 7 ***:.*= 8.498 **=6.:*8 *726.74

2 *4=4.*26 *2==.464 *4.89 *2:9.=*4

4 *627.:6 *467.*4 *6:.68= *67*.=8=

6 *69.422 *6*2.*8: *84.8:* *87:.426

8 *97:.4*: *=64.7=* *72.6 *:*6.9=

= *84*.9 *69:.82 *=87.68 *899.:4

E$A 7 ***:.*= 8.498 **=6.:*8 *726.74

4 *4*:.6 *22:.**= *6*9.784 *47*.622

6 *492.4* *2=.769 *6:2.26* *49.:*:

8 *62.:* *4=7.748 *88=.69 *6=*.:68

= *62.892 *628.:86 *=*6.=76 *824.86*

9 *82.*88 *6=2.*92 *=8.4* *8=:.698


(n order to evaluate the effect of S#S and E$A type polymer on the moisture

susceptibility characteristics of samples prepared with different types of aggregate >basaltH

limestone mixture and limestone? the additive content is plotted against the values of the

(!S for both control >dry? and conditioned specimens. !he !S" is also introduced in the

same figure based on each additive content. !he results are presented in 0igs.4.4 and 4.6.

33


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Fig.. ITS an0 TSR '$su"ts 3&' $a(! t+$s &3 agg'$gat$ *it! SBS PMA


34


35/39

Fig..4 ITS an0 TSR '$su"ts 3&' $a(! t+$s &3 agg'$gat$ *it! EVA PMA


As depicted in 0igs.4.4 and 4.6 and !able 4.: for all samples involving S#S and

E$A polymer the (!S of the samples prepared with basaltHlimestone aggregate was greater

than the (!S of the samples prepared with limestone aggregate. !his difference may be

attributed to the rigidity of the basalt aggregate. #esides the (!S of the samples containing

polymer was greater than the (!S of the unmodified mixtures. !his indicated that the

mixtures containing additives have higher values of tensile strength at failure under static

loading. !he greater the tensile strength of the modified mixtures as compared to

unmodified mixture also indicates greater cohesive strength of the S#S and E$A.

!he (!S test results are also used to evaluate the crac)ing properties of the

pavement. Numerous previous study have shown that higher tensile strength values

correspond to higher crac)ing resistance. As presented in 0igs.4.4 and 4.6 and !able 4.:;

polymer and hydrated lime modified mixtures with higher (!S values appear to be capable

of withstanding larger tensile strains prior to crac)ing compared to unmodified mixtures. (n

addition among the samples prepared with the same type of aggregate the samples

35


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prepared S#S PM# exhibited greater resistance to crac)ing compared to E$A PM#

samples.

As presented in 0igs.4.4 and 4.6 for both types of aggregate as the S#S and the

E$A polymer content increases the !S" values increase as well. !his indicated that the

resistance of asphalt mixes to the detrimental effect of water increases with the increase in

polymer content. 1owever no significant change in the values of !S" was observed on

reaching the S#S and E$A content of 8G and =G respectively.

0or all S#S and E$A polymer contents the !S" of basaltHlimestone aggregate was

smaller than the !S" values related to limestone illustrated in 0igs.4.4 and 4.6. !his

indicated that the introduction of basalt aggregate into the limestone increases the

susceptibility of the mixture to moisture damage.

As seen in 0igs.4.4 and 4.6 for both types of aggregate prepared with the same

polymer content the !S" of mixtures prepared with the S#S PM# was greater than the

!S" of mixtures prepared with the E$A PM#. !his indicates that mixtures including the

E$A PM# exhibit more stripping potential compared to the S#S PM#.

.2. Su%%a'+

Moisture damage in asphalt mixtures is a complex mechanism and has many

interacting factors such as mixture design proper construction traffic and environment.

Among these factors the properties of the additives was important. 0rom the study the

following conclusions were drawn.

o Mixtures prepared with S#S and E$A PM# display reduced stripping

potential and moisture susceptibility than mixtures prepared with base

bitumen for all types of aggregate >basaltHlimestone aggregate mixture and

limestone aggregate?. As a conseCuence it can be concluded that polymer

modified bitumen provides increased adhesion to the aggregate and creates a

networ) structure within the base bitumen.

o S#S polymer addition has shown a greater degree of improvement in

resistance of asphalt mixture to the detrimental effect of water compared to

E$A polymer addition.

o A clear distinction between the mixtures prepared with the same polymer

type indicates that at a given polymer content such as 4G the mixtures

prepared with basaltHlimestone aggregate exhibit more moisture

susceptibility than the mixture prepared with limestone aggregate. !his

36


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difference may be attributed to the formation of a wea) bond between the

basalt aggregate and the bitumen both of which are acidic in character.

4. CONCLUSIONS

#y reviewing the literature the following conclusions were obtained@

37


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Marshall stability values of modified mixes was higher than the control mixtures. +nly

AP mixture gave lower stability. A maximum stability value of 947)g was obtained for

PE mix. AP and #E mixtures had lower flow value.

Polymer modified asphalt had higher values of tensile strength at failure. !he PE mix

had maximum tensile strength of about 778

7

%?. Athigher temperature the value of stiffness modulus of conventional and modified mixes

converges. Static creep test does not reflect the performance of modified asphalt.

Modified mixtures had more resistance to permanent deformation. S#S mixture showed

highest resistance to permanent deformation. Mixtures prepared with S#S and E$A PM# showed reduced stripping potential and

moisture susceptibility than mixtures prepared with base bitumen for all types of

aggregate >basaltHlimestone aggregate mixture and limestone aggregate?.

Polymer modified bitumen provides increased adhesion to the aggregate and creates a

networ) structure within the base bitumen. S#S polymer addition has shown a greater degree of improvement in resistance of

asphalt mixture to the detrimental effect of water compared to E$A polymer addition. Mixtures prepared with basaltHlimestone aggregate exhibit more moisture susceptibility

than the mixture prepared with limestone aggregate.

REFERENCES

*. %agri 3or)em #ura) Sengo >277? RPredicting stripping and moisture induced

damage of asphalt concrete prepared with polymer modified bitumen and hydrated

lime Source'www.elsevier.com %onstruction and #uilding Materials'24 Pages'

2229 to 224=.

2. Sureyya !ayfur 1alit +en Ata)an A)soy >2779? R(nvestigation of rutting

performance of asphalt mixtures containing polymer modifiers Source'

www.elsevier.com %onstruction and #uilding Materials'2* Pages'42: to 449.

4. Won Jun Woo, Edward Ofori-Abebresse, Arif Cowdur!, "2007#

$Polymer Modified Asphalt ,urability (n Pavements %ourse-www&n'is&(o)

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6. /et)im /ildirim >2779?RPolymer modified asphalt binders Source'www.

elsevier.com %onstruction and #uilding Materials'2* Pages'== to 92.

8. R0lexible pavement distress [email protected])s.ac.gov

&operations& pavement management.htm

Documents

Performance Evaluation of Polymer Modified Asphalt Mix