Rut resistance behavior was tested for 9 types of asphalt mixtures and 10 types of pavement structures combining different mixtures. Double-deck structures, whether with different or same mixtures, showed considerably poorer rut resistance than single-layer structures. Using modified binders in the lower layer did not significantly improve rut resistance of double-deck structures. Current Chinese specifications setting rut resistance criteria based on single-layer tests is unreasonable for multi-layer pavements.

1. Rut Resistance Behavior of Pavement Structures
Combined by the Different Asphalt Mixtures
FAN Tong-jiang
Professor, School of Civil Architecture
Chongqing Jiaotong University
Chongqing 400074, China
ftj.163@163.com
ABSTRACT--- In this paper rut resistance behavior of Super-Viscous Modified Bitumen(SVMB) respectively, were
pavement structures combined by the different asphalt mixtures is experienced by China’s wheel tracking tester in lab.
presented. Nine types of Hot Mix Asphalt (HMA) and ten types of Experimental results showed that the rut resistance behavior of
their different combinations are experienced with China’s wheel all double-deck asphalt concrete structures whether it is make
tracking tester in this study. They are composed of three types of
aggregate gradation including a coarse, a middle and a fine
up of different HMA or same, are considerably poor than that
gradation of norminal aggregate size of respectively 26.5mm, of monolayer asphalt concrete structures, for example, the
19mm and 13.2mm, and three types of asphalt binders including a former DS almost had only half of that of the latter but the
Conventional Bitumen, a Modified Bitumen and a Super-Viscous former Rates of Deformation (RD) had an increase of about
Modified Bitumen. Experimental results showed that the rut 50% than that of the latter, and there is no exception even
resistance behavior of all double-deck asphalt concrete whether it though for a combination of SVMB and coarse aggregate
is made up of different HMA or the same, is considerably poorer gradation. Results also indicated that if the HMA of upper-layer
than that of relative monolayer asphalt concrete. There is no of double-deck asphalt concrete is same type, using the MB or
exception even to a combination of Super-modified bitumen with SVMB binder substituting the CB binder in the lower layer of
coarse aggregate gradation. The results also indicated that if the
Conventional Bitumen binder is substituted by the Modified
double-deck asphalt concrete, rut resistance property not
Bitumen or Super-Viscous Modified Bitumen binder in the improved remarkably. Therefore in China’s specifications
down-layer of double-deck asphalt concrete when the HMA of setting the DS index of monolayer asphalt concrete structures
up-layer of double-deck asphalt concrete structure is the same type, to meet the requirement of 800(times/mm) as a criterion of
rut resistance property has been improved but not remarkably. controlling rut of multi-layer asphalt concrete structures is
Therefore in China’s Specifications for setting the dynamic unreasonable.
stability of monolayer asphalt concrete to meet the requirement of
800(times/mm) as a criterion of controlling rut of multi-layer 2. MATERIALS AND METHODS
asphalt concrete is unreasonable.
2.1 Characteristics of Binders Gradation Used in Test
Keywords: rut resistance behavior; pavement structures;
asphalt mixtures; aggregate gradation; dynamic stability. Three types of binders and their technical characteristics are
listed in table 1.And the course aggregate and fine aggregate
1 INTRODUCTION used in test are all the crushed lime stone, and the filter is the
powder milled with clear, harder lime stone and all their
Rutting,or permanent deformation has been and continues to
technical characteristics are listed in table 2.
be a major problem in Hot Mix Asphalt (HMA) pavements in
the world, especially in high temperature areas and at heavy Table 1 Characteristics of Binders Applied in Test
traffic load. And it is caused by consolidation or lateral Types of Binders
movement, or both, of the HMA under repeated traffic.There are Items of test
CB 60/80 MB SVMB
many academic papers [1, 2, and 3]that have presented the research
results for rut resistance behavior of HMA. It is recognized to Penetration at( 25 ,100gr,5sec) ( 0.1mm) 69 46 41
generally occurs in the top 100 mm (4 in) of the HMA Softening Point ( Ring&Ball) ( ) 48 73 91
structure[4 and 5]. However, Chinas Specifications for Design of Durability(15 ) (cm) 100 43.1 27
Highway Asphalt Pavement[6] regulates the Dynamic Stability
Solubility(Trichloroethane) (% ) 99 99 99
(DS) of 800(times/mm), which is obtained by testing monolayer
asphalt concrete structure that is a thickness of 5mm samples, as Specific Gravity (20 /20 ) 1.016 1.007 1.017
a criterion of controlling rut of multi-layer asphalt concrete Dynamic Viscosity/Pa.s (175 ) 0.287
structures. In practice many expressways that were constructed (170 ) 0.277 0.457
based on that criterion mentioned above have become conscious
(150 ) 0.213 0.427 7.17
of severe rutting to have taken place. What causes result in this
problem to take place? In order to understand real causes, in this (135 ) 0.477 2.713 16.82
study nine types of hot mix asphalt and ten types of their types a (60 ) 87796
gradation of maximum aggregate size of 31.5mm, 26.5mm and Aging Test(RTFO)
aggregate gradation including a coarse, a middle and a
Mass loss (%) 0.15 0.24 0.04
fine16mm respectively, and three types of asphalt binder
including different combination, which are composed of three of Penetration Ratio regarding original(%) 73.5 81.4 71.4
a Conventional Bitumen(CB), a Modified Bitumen(MB) and Durability (15 ) (cm) 100 22.5 15.5
978-1-4244-7161-4/10/$26.00 ©2010 IEEE
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2. Table 2 Characteristics of Coarse aggregate, Fine aggregate and Filter 300 mm wide, 300 mm long, but vary thichness according to
Coarse Fine three times of norminal dimensions of gradation. And for the
Items of test Aggregate Aggregate Filter
double-deck asphalt concrete, all specimen dimensions are
Crushed index values % 20.3 300 mm wide, 300 mm long,but total thichness for each a
Los Angeles abrasion loss % 24.1 specimen is the sum combined by the up-layer plus the
down-layer respectively according to three times of norminal
Specific gravity (20 20 ) 2.732 2.693 2.713
dimensions of gradation. The specimens were maintanced a
Water absorption % 1.5 1.9 contant temperatures at 60°C above 5 hours and then tested.
Robustness % 9.8 12 Test samples are loaded for a hour at tire contact pressures of
0.7MPa. The travel speed of the wheel move back and forth
Contents of soft rock % 3
approximately 42 times per 60 second. Data, which is the
Contents of flat and slender particles % 15 average value of four specimens tested, is automatically
Contents of less than 0.075mm % 1 2.5 collected and calculated by the computer.The dynamic
stability(DS) of samples for asphalt mixtures was calculated by
Sand equivalences % 66 62 the formula (1):
(t 2 − t1 ) × N × C
Sand flow s 31.5
The graphs of three types of aggregate gradation, which meet DS= × C2 (1)
d 2 − d1
1
requirements of China’s Techincal specifications for
construction of highway asphalt pavements[7]are shown in fig.1. Where is
DS- the dynamic stability of asphalt mixtures times/mm.
d1-deformations corresponding with time t1 =45min
mm.
d2- deformations corresponding with time t2 =60min
mm.
C1-revise coefficient for type of tester.It is applied to 1.0
when the tester is droven by the crank and connecting rod
mechanism; It is applied to 1.5 when the tester is droven by
the chain mechanism.
C2- sample coefficient.It is1.0 for the sample being prepared
by 300 mm wide, 300 mm long.
N- The travel speed of the wheel, it is approximately 42
times /min.
2.2 Description of Symbols Used in Paper 3 EXPERIMENTAL RESULTS AND DISCUSSION
In order to have a simple and clear description symbols for
grading types, binder types and types of mixtures are defined 3.1 Experimental Results
respectively in table 3 and table 4. Experimental results for monolayer and double-deck asphalt
Table 3 Types of Gradations and Binders and all their Symbols
concrete are respectively shown in Table 5 and Table 6.
Grading Types Symbols Binder Types Symbols
Table 4 Types of the Mixtures and the Composite Structures and their Symbols
Coarse Grading Maximum Conventional Monolayer Asphalt Combination of Double-deck Asphalt
Size 31.5mm Gc Bitumen60/80 CB Concrete Structures Concrete Structures
Middle Grading Maximum Types of
Size 26.5mm Gm Modified Bitumen MB Mixtures Symbols Types of Mixtures Symbols
Fine Grading Maximum Super-Viscous Gc with Gc CB Up-layer: Gm CB(60/80) plus
Size 16mm Gf Modified Bitumen SVMB CB(60/80) Down-Layer: Gc CB(60/80)
2.3 Test Methods Gm CB Up-layer:Gm MB plus
Down-Layer: Gc CB(60/80)
For simulating research of rut resistance behavior of Gf with Gf CB
CB(60/80)
HMA the most common type of laboratory equipment to be
Gc with
used is generally a Loaded wheel testers (LWT).They include MB Gc MB
the Georgia Loaded Wheel Tester (GLWT), Asphalt Pavement
Analyzer (APA), Hamburg Wheel Tracking Device(HWTD), Gm MB
LCPC (French) Wheel Tracker, Purdue University Laboratory
Wheel Tracking Device(PURWheel), and one-third scale Model Gf with MB Gf MB
Mobile Load Simulator (MMLS3) [4]. In the paper China’s
Wheel Tracking Tester (Accuracy of deformation sensor is up to Gc SVMB
0.01%) similar to GLWT was used. All test was carried out Gm with Gm SVMB
according to the Standard Specification’s SVMB
Gf with
method,T0719-1993,Standard test Methods of Bitumen and SVMB Gf SVMB
Bituminous Mixtures for Highway Engineering[8]. All specimen
dimensions for the monolayer asphalt concrete are respectively
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3. Table 5 Experimental Results for the Monolayer Asphalt Concrete structures
1 s1 t1 y1
Types of
Asphalt 1 s2 t2 y2
Concrete
Gc CB 1087 3.86 0.0386 5.2 1 s3 t3 y3
Gc MB 4400 9.6 0.0096 6.7 1 s4 t4 ˆ
k0 y4
Gc SVMB 4440 10.5 0.0095 5.65
Gm CB 1189 6.53 0.0353 5.4 1 s5 t5 ˆ ˆ y5
Gm MB 3280 12.8 0.0128 7.84 X= k = k1 Y=
Gm SVMB 4200 10.55 0.01 6.75
1 s6 t6 y6
ˆ
k2
Gf CB 868 4.84 0.0484 7.9 1 s7 t7 y7
Gf MB 2832 14.8 0.0148 12.18
Gf SVMB 3360 12.55 0.0125 4.76 1 s8 t8 y8
Table 6 Experimental Results for the Double-deck Asphalt Concrete structures 1 s9 t9 y9
Combined by the Different Asphalt Mixtures
1 s10 t10 y10
Combination of
Asphalt Concrete
Structures ˆ ˆ
k =X/Y; Y=X k .
Gm CB+ Gc CB 630.5 6.67 0.0667 12.4 Y =the DS’s or the RD’s of double-deck asphalt concrete.
Gm MB+ Gc CB 1832 12.9 0.0229 3.6 X1 =the DS’s or the RD’s of the monolayer down-layer
Gm SVMB+ Gc CB 1890 8.22 0.0222 4.3 asphalt concrete.
Gm MB+ Gc SVMB 2102 12.5 0.02 7.2 X2 =the DS’ s or the RD’s of the monolayer up-layer asphalt
Gm SVMB+ Gc SVMB 2044 12.04 0.0205 4.1
concrete.
Calculations based upon experimental data in table 5 and
Gf CB+ Gc CB 541.5 7.76 0.0776 14.7 table 6 by (2) can be obtained respectively:
Gf MB+ Gc CB 1339 13.1 0.0314 8.1 DSdouble=120.15+0.0501x1+0.4214x2 (3)
Gf SVMB+ Gc CB 1443 12.91 0.0291 14.5
RDdouble=4.4447×10-3+0.0896x1+1.5133x2 (4)
Gf MB+ Gc SVMB 1451 10.29 0.029 4.8
Gf SVMB+ Gc SVMB 1535 11.28 0.0275 11.2 Where DSdouble =the DS of double-deck asphalt concrete.
RDdouble= the RD of double-deck asphalt concrete.
3.2 Discussion The relationship between the experimental value and the
3.2.1 Correlation of the DS or the RD calculating value for the DS’s and for the RD’s obtained
respectively by the (3) and the (4) and their residuals are shown
Comparing the data in table 5 and in table 6 can know that respectively in fig.2 and in fig. 3.The results indicated that the
the rut resistance behavior of all double-deck asphalt concrete values predicted by the (3) or the (4) have a good linear
structures whether they made up of different HMA or same, are relationship with experimental value whether is for the DS’s or
considerably poor than that of monolayer asphalt concrete for the RD’s. So we recognize that the (3) and the (4) predicting
structures, for example, the former the DS almost had only half the DS’s or the RD’s of double-deck asphalt concrete with the
of that of the latter but the former the RD had an increase of monolayer DS’s or RD’s are reliable and accurate.
about 50% than that of the latter, and no exception even though
Relationship between experimental value and calculating value for DS (Model A)
for a combination of SVMB with coarse aggregate gradation. 2500
Results also indicated that if the HMA of upper-layer of 2000
Experimental value
double-deck asphalt concrete is same type, using the MB or 1500
y = 1*x - 1.2e-013
SVMB binder substituting the CB binder in the lower layer of
1000
double-deck asphalt concrete, rut resistance property not
improved markedly. From the data in the table mentioned 500 data 1
linear
above,we can build the relationships of the DS or the RD 0
400 600 800 1000 1200 1400 1600 1800 2000 2200
between the double-deck asphalt concrete structures and the Calculating value
different monolayer asphalt concrete structures as the following residuals
model: 300 Linear: norm of residuals = 554.5275
200
y=k0+k1x1+k2x2 (2) 100
0
-100
ˆ
The matrix X, k Y: -200
-300
Where 600 800 1000 1200 1400 1600 1800 2000
Figure 2 The relationship between experimental value and calculating value for
the DS and residuals
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4. Relationship between experimental value and calculating value for RD (Model A)
but a considerable improvement for the MB or the SVMB.
0.08
Experimental value
y = 1*x - 2.7e-017
0.06
0.04
data 1
0.02 linear
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09
Calculating value
residuals
0.05
Linear: norm of residuals = 0.010101
0
-0.05
0.03 0.04 0.05 0.06 0.07 0.08
Figure 3 The relationship between experimental value and calculating value
for the RD and residuals
3.2.2 Influence of the combination of different asphalt
mixtures on rut resistance behavior
As showed in Fig.4 and in Fig.5, in the same group whether
it is for the Down-layers or for the up-layers only the types of
binders change the DS of the pavement structures combined by
different asphalt mixtures have quite evident difference. In the
same group when keeping the mixtures of the Down-layers are
the same and the binders of the Up-layer’s mixtures use the
4 SUMMARY AND CONCLUSIONS
modified asphalt substituting the conventional asphalt, the Evaluating the rutting resistance behavior of the
enhancement of the DS’s for the double-deck asphalt concrete HMA using the results of wheel tracking test, the DS’s of
are the more evident than that of the DS’s for the double-deck the monolayer asphalt concrete are the evident large than
asphalt concrete when keeping the mixtures of the Up-layers are that of the composite double-deck layer asphalt concrete.
the same then using the modified asphalt substitute the This state that the deformation of asphalt concrete
conventional asphalt of the Down-layers. This showed that pavement increase with the increase of asphalt concrete
using the high-quality binder in asphalt concrete of the thickness and the DS’s of asphalt concrete pavement
Up-layers will develop most-effeteness than that of using the decrease with the decrease of asphalt concrete thickness.
high-quality binder in the Down-layers. However, the results in Hence not using the DS’s of the monolayer asphalt
Fig.6 showed that in the same group when keeping every concrete structures substitutes that of the composite
combination of the double-deck asphalt concrete in the grade multi-layer asphalt concrete as a criterion of controlling rut
are the same, the DS’s improvement for the high property binder, of multi-layer asphalt concrete pavement.
MB or SVMB, used in the Up-layers and the Down-layers are
not evident than that of only the high property binder, MB or However, utilizing the rutting experimental
SVMB, used in the Up-layers but the CB used in the result of the different types of monolayer asphalt concrete
Down-layers . structure we can build a relationship of the differently
composite multi-layers asphalt concrete structure with that
Furthermore, as showed in Fig. 7,when in the same group of the different types of monolayer asphalt concrete
keeping the mixtures of the Down-layers and the binders of the structure to evaluate the rutting resistance behavour of
Up-layers are the same, only changing the fine grade in the composite multi-layers asphalt concrete structure.
Up-layer’s into the middle grade, the DS’s for the double-deck
asphalt concrete only have a limited improvement for the CB The high property binder used in Up-layer of
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5. pavement can play the more-effective rutting resistance
behavior than used in the Down-layer of pavement.
However For all using the high property binder in the Up-
layer and the Down-layer at the same time, the rutting
resistance property of asphalt concrete structure can not
greatly get increasing at a direct proportion to the DS’s of
the monolayer asphalt concrete structures . When the fine
grade in the Up-layer’s be substituted by the middle grade,
the DS’s for the double-deck asphalt concrete can
evidently improve for the MB or the SVMB but only have
a limited improvement for the CB.
Using the asphalt concrete structure of the CB
plus course gradation in the Down-layer of pavement,there
is a equivalent rutting resistance property but the most
cost-effective than using the asphalt concrete structure of
the MB or the SVMB plus course gradation in the
Down-layer of pavement.
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