ORIGINAL ARTICLE

Simplified viscosity evaluating method of highviscosity asphalt binders

Lihan Li • Han Geng • Yanna Sun

Received: 22 July 2013 / Accepted: 26 March 2014

� RILEM 2014

Abstract In order to establish a simplified viscosity

evaluating method of high viscosity asphalt binders

(HVABs), shear rate sweep test in the shear rate range

of 1.25 9 10-6–1,250 s-1 was performed. Results

showed that HVABs exhibited yield pseudo-plastic

fluid behavior at 60 �C and the overlapped range of the

first Newtonian region was 8 9 10-5–2 9 10-2 s-1.

Based on the results, the simplified shear rate sweep

test in the shear rate range of 0.001–0.1 s-1 was

proposed and low shear viscosity at 0.01 s-1 (LSV0.01)

was suggested as the viscosity evaluating indicator of

HVABs, which exhibited both close values to zero

shear viscosity and significant correlation with rutting

resistance of porous asphalt.

Keywords High viscosity asphalt binder �Shear rate sweep test � Yield stress �First Newtonian region � Zero shear viscosity �Low shear viscosity � Capillary viscosity

1 Introduction

High viscosity asphalt binders (HVABs) were devel-

oped by Japanese companies to improve rutting

resistance and durability of porous asphalt [15].

HVABs are compound modified asphalt binders,

which are mainly modified by styrene–butadiene–

styrene (SBS), mineral oil and petroleum resin [9].

SBS is the main component of HVABs, which is

commonly 6–12 % of base binder by weight [21].

According to Japanese specification in 1996, the

capillary viscosity of HVABs for porous asphalt at

60 �C should be no less than 2 9 104 Pa s and the

softening point should be no less than 80 �C [10]. The

Chinese specification for asphalt pavement construc-

tion has the same requirements for HVABs as the

Japanese specification mentioned [16]. As the tech-

nology improvement for producing HVABs, capillary

viscosity of typical HVABs at 60 �C in Japan and

China is higher than 1 9 105 Pa s [13, 15].

According to Sybilski’s [19] study, polymer mod-

ified binders exhibit the behavior of pseudo-plastic

shear-thinning liquid, whose viscosity is dependent on

shear rate. Pseudo-plastic shear-thinning liquid and

yield pseudo-plastic shear-thinning liquid are typical

non-Newtonian liquids. Their behaviors are approxi-

mated by power law equation and Herschel–Bulkley

equation, which are shown in Eqs. (1) and (2),

respectively [12]. Typical log–log plot of the relations

between viscosity, shear stress and shear rate for both

liquids are shown in Fig. 1 [4]. For pseudo-plastic

liquids, shear rate increases in function of power along

with the increase of shear stress. In log–log plot,

viscosity approximates a constant value as shear rate

tends to zero, which is the value of zero shear

L. Li � H. Geng (&) � Y. Sun

Key Laboratory of Road and Traffic Engineering of the

Ministry of Education, Tongji University, 1239 Siping

Road, Shanghai 200092, People’s Republic of China

e-mail: hanprof@126.com

Materials and Structures

DOI 10.1617/s11527-014-0299-2

viscosity. For yield pseudo-plastic liquids, shear rate is

zero when shear stress is lower than the yield stress.

The liquid starts to flow when shear stress is higher

than the yield stress. In log–log plot, when shear rate

goes to zero, shear stress approximates the yield stress

and viscosity tends to infinity, as viscosity equals the

ratio of shear stress to shear rate.

s ¼ K1 � c0n1 ð1Þ

s ¼ s0 þ K2 � c0n2 s � s0ð Þc0 ¼ 0 s � s0ð Þ

(; ð2Þ

where s is shear stress, Pa; s0 is yield stress, Pa; c0 is

shear rate, s-1; K1 and K2 are consistency index, Pa s;

n1 and n2 are flow behavior index, dimensionless.

For both pseudo-plastic liquids and yield pseudo-

plastic liquids, viscosity values vary with shear rate

levels of the test method. In vacuum capillary

viscosity test, flow time and viscosity are the only

two parameters can be obtained. However, the shear

rate corresponding to capillary viscosity could not be

obtained. As the time for binders to be drawn up

through a capillary tube by means of vacuum varies in

the range of 60–1,000 s, capillary viscosity of binders

may be compared at different shear rate [2]. In 2006,

the Japanese specification was revised and the

requirement for capillary viscosity at 60 �C was

cancelled in the revised specification [11]. Compared

to capillary viscosity, zero shear viscosity (ZSV) has

been commonly accepted as an indicator of asphalt

mixtures’ resistance to permanent deformation in

European countries [20]. The previous study of the

author found that ZSV of HVABs at 60 �C exhibits

significant correlation with rutting resistance and

raveling resistance of porous asphalt [13]. ZSV at

60 �C has been used as viscosity evaluating indicator

of HVABs for porous asphalt in Shanghai for over

3 years since 2010 [18].

The creep test, shear rate sweep test and frequency

sweep test are commonly used for ZSV measurement.

The creep test is conducted by dynamic rheometer in

creep mode. For polymer modified asphalt binders,

shear stress applied is 10-50 Pa and the loading time is

4 h [6]. The shear rate sweep test is conducted by

dynamic rheometer in steady flow mode and ZSV can

be estimated by Carreau model base on viscosity

versus shear rate curve [13]. The frequency sweep is

conducted by dynamic rheometer in oscillation mode

and the strain level of 0.1 is commonly applied [5, 7].

Cross model can be applied to estimate ZSV.

Although a wealth of experiences has been accu-

mulated by previous studies, there are still some

problems to be solved for ZSV measurement of

HVABs. Firstly, in creep test, it takes 8–15 h to obtain

the steady-state flow and ZSV of HVABs at 60 �C,

which is not practical for routine viscosity evaluation

of HVABs [6, 14]. Secondly, shear rate sweep test is

time consuming and lasts at least 60 min. Thirdly, for

both shear rate sweep test and frequency sweep test,

data fitting by Cross or Carreau model is required to

estimate ZSV and thus the results of ZSV could be

different if the tests are not conducted in the same

shear rate range. In summary, a simplified measure-

ment of ZSV or its alternative indicator is necessary

for viscosity evaluation of HVABs.

2 Objectives

The main objectives of this study are to establish

simplified measurement of ZSV or its alternative

indicator for viscosity evaluation of HVABs based on

Fig. 1 Log–log plot of the

relations between viscosity,

shear stress and shear rate

for typical shear-thinning

liquids

Materials and Structures

the analysis of viscosity (or shear stress) versus shear

rate curve under low shear rate condition, and to verify

the viscosity evaluating indicator based on the corre-

lation analysis between indicators of asphalt binders

and rutting resistance indicator of porous asphalt.

3 Experimental

3.1 Materials

In this study, two neat binders, one styrene–butadiene–

styrene (SBS) binder, one high modulus asphalt binder

(HMABs) and six HVABs were included. Penetration

at 25 �C (Pen), softening point (TR&B), capillary

viscosity (gc) by vacuum capillary viscometer at

60 �C [2], G*/sind at 60 �C [1] and non-recoverable

creep compliance at 0.1 kPa and 60 �C (Jnr0.1) [3] are

shown in Table 1.

Porous asphalt with the nominal maximum aggregate

size of 13.2 mm (PA-13.2) was designed for wheel

tracking test. The traffic volume for the mix design was

equal to 4 9 106 equivalent single axle loads (ESALs).

Asphalt content of the mixture was 4.2 % and air voids

were 20 ± 1 %. Crushed diabase was used as coarse

aggregates (4.75–13.2 mm) and limestone was used as

fine aggregates (0.075–2.36 mm). The voids in the

mineral aggregate (VMA) was 28.3 % and the voids

filled with asphalt (VFA) was 29.4 %. Binders No. 1,

No. 3, No. 4, No. 5, No. 6 and No. 7 were selected for

wheel tracking test. The values of dynamic stability

(DS) by wheel tracking test of porous asphalt are shown

in Table 1. The gradation of porous asphalt is shown in

Table 2. Test method for wheel tracking test is

described in the sections below.

3.2 Shear rate sweep test

Shear rate sweep test was used to obtain viscosity

versus shear rate curve [13]. This test was performed

by AR 1500ex rheometer in steady flow mode, with

25 mm diameter plates, 1,000 lm thickness of asphalt

samples and water bath at 60 �C. In order to obtain

viscosity versus shear rate curve in a wide range, shear

rate range of 1.25 9 10-6–1,250 s-1 was applied. In

the steady flow mode for shear rate sweep test,

successive shear rate was applied and data was

sampled under equilibrium conditions. In the study,

five shear rate levels were applied per decade with

equidifferent progressive increase in logarithmic

coordinates.

Carreau model was used to estimate ZSV of asphalt

binders in the study, which is shown in Eq. (3). The

first Newtonian region was defined as the shear rate

range corresponding to 0.8–1.0 time the value of ZSV.

g� g1g0 � g1

¼ 1

1þ K3 � c0ð Þ2� �n3=2

; ð3Þ

where c0 is shear rate, s-1; g is viscosity, Pa s; g0 is

zero shear viscosity, Pa s; g? is infinite shear rate

viscosity, Pa s; K3 is shear rate coefficient, s; n3 is

shear rate index, dimensionless.

The previous study of the author found that

viscosity of binders tends to infinity when the shear

rate is lower than 10-5 s-1 in shear rate sweep test at

60 �C [13]. The phenomenon indicates that the asphalt

Table 1 Indicators of binders and mixtures in the study

Binder no. Binder type Pen (0.1 mm) TR&B (�C) gc (Pa s) G*/sind (kPa) Jnr0.1 (kPa-1) DS (passes/mm)

1 Neat 59.1 46.0 222.6 1.90 5.044 283

2 Neat 56.4 46.8 326.0 2.61 – –

3 SBS 51.8 76.0 25,050 6.92 0.136 3,923

4 HMABs 25.6 66.8 7,225 18.79 0.140 5,132

5 HVABs 41.4 78.8 18,076 8.46 0.172 5,737

6 HVABs 37.4 87.8 160,320 11.58 0.138 8,639

7 HVABs 46.2 84.9 337,617 11.82 0.054 8,253

8 HVABs 45.3 86.5 47,152 7.57 – –

9 HVABs 61.6 82.5 198,066 5.95 – –

10 HVABs 51.0 85.1 91,072 10.42 – –

Materials and Structures

binders may exhibit yield pseudo-plastic fluid behav-

ior at 60 �C [8]. Herschel–Bulkley model was selected

to estimate yield stress of asphalt binders in the study,

which is shown in Eq. (2).

3.3 Wheel tracking test

The samples for wheel tracking test were compacted in

a steel mold with internal dimensions of 300 9 300 9

50 mm. At least two replicates were compacted for

each binder. The wheel tracking test was performed by

QCZ-2 wheel tracking machine produced by Beijing

Jingu Measuring and Control Technology Institute.

The tire of the machine is made of solid rubber. The

outside diameter, width and thickness of the rubber

tire are 200, 50 and 20 mm respectively. The pressure

of the rubber tire is 0.7 MPa at 60 �C.

Test procedures were conducted according to the

Chinese specification [17].The samples were condi-

tioned at 60 �C for 5 h before testing. The samples

were subjected to the tire with a travel distance of

230 mm and a frequency of 21 cycles per minute (42

passes per minute) for 1 h. DS is the indicator for

rutting resistance evaluation in the test, which is

calculated based on data of the last 15 min according

to Eq. (4).

DS ¼ 60� 45ð Þd2 � d1

; ð4Þ

where DS is dynamic stability of asphalt mixture,

passes/mm; d1 is rutting depth at 45 min, mm; d2 is the

rutting depth at 60 min, mm; N is the frequency of the

tire, 42 passes per minute.

4 Results and discussion

4.1 Yield stress and zero shear viscosity

Shear rate sweep test were performed in the shear rate

range of 1.25 9 10-6–1,250 s-1 at 60 �C. Shear

stress versus shear rate curves fitted by Herschel–

Bulkley model and viscosity versus shear rate curves

fitted by Carreau model are shown in Fig. 2. As

shown, when the shear rate is lower than 10-5 s-1, for

10 binders in the study, the viscosity tends to infinity

and the shear stress approximates a constant value.

This phenomenon indicates that asphalt binders

exhibit yield stress at 60 �C. When the shear rate

was higher than 10-5 s-1, Carreau model agrees well

with viscosity versus shear rate data points of the

binders. Based on the results, it was concluded that

asphalt binders exhibited yield pseudo-plastic fluid

behavior, rather than pseudo-plastic fluid behavior as

previously considered. As the ZSV does not actually

exist for binders with a yield stress, low shear viscosity

in the first Newtonian region shows its potential for

viscosity evaluating of HVABs.

Yield stress and ZSV estimated by regression

analysis are shown in Table 3. The values of ZSV in

the study were estimated by Carreau model based on

part of viscosity versus shear rate curve shown in

Fig. 2. The part of the curve where viscosity tends to

infinity as shear rate decrease was not included for

ZSV estimation. As shown, ZSV of 10 binders in the

study at 60 �C is 184.1–73,880 Pa s and the yield

stress is 0.03–0.81 Pa. For all HVABs with ZSV

higher than 2 9 104 Pa s (Nos. 6–10), the yield stress

is 0.17–0.81 Pa, which is 1.1–26 times higher than that

of the other binders (Nos. 1–5) in the study. The

overlapped range of the first Newtonian region of

HVABs with ZSV higher than 2 9 104 Pa s (Nos.

6–10) is 7.6 9 10-5–2.2 9 10-2 s-1.The overlapped

range of the first Newtonian region of 10 binders in the

study is 5.0 9 10-3–1.0 9 10-2 s-1. The test results

indicate that the low shear rate viscosity (LSV) in the

range of 5.0 9 10-3–1.0 9 10-2 s-1 may exhibit

close viscosity values to ZSV of asphalt binders.

4.2 Low shear viscosity

The LSV in the range of 1.0 9 10-4–1.0 9 10-1 s-1

and LSV to ZSV ratio are shown in Table 4. Statistic

parameters including the average and variance of LSV

to ZSV ratio were calculated. As shown, both the

average and variance of the ratio decrease as the shear

rate increase. When shear rate is 0.01 s-1, the average

of LSV to ZSV ratio is 95.8 % and the variance of the

Table 2 Gradation of porous asphalt in the study

Sieve size (mm) 16 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075

Percentage passing (%) 100 94.6 70.9 23.2 15.6 11.1 8.7 6.2 4.9 4.0

Materials and Structures

Fig. 2 Results of shear rate

sweep test

Materials and Structures

ratio is 9.1 %. The results showed that low shear

viscosity at 0.01 s-1 (LSV0.01) exhibited close values

to ZSV in the study.

4.3 Capillary viscosity

The values of LSV0.01, ZSV and capillary viscosity by

vacuum capillary viscometer at 60 �C are shown in

Fig. 3. As shown, the values of LSV0.01 and ZSV are

close. For all the binders except No. 4, the values of

capillary viscosity are higher than the values of

LSV0.01 and ZSV. For HVABs of No. 6, No. 7 and

No. 9, whose capillary viscosity is higher than

1 9 105 Pa s, the difference between capillary vis-

cosity and ZSV (or LSV0.01) is significant. According

to Tables 1 and 3, the values of capillary viscosity are

3.0–7.8 times higher than ZSV for these three binders.

For the other HVABs (No. 5, No. 8, No. 10), the values

of capillary viscosity are 0.1–0.8 time higher than

ZSV.

The shear rate corresponding to capillary viscosity

could not be obtained in vacuum capillary viscometer

test. However, it can be estimated based on the

hypothesis that the relation between shear stress and

shear rate in vacuum capillary test conforms to

Herschel–Bulkley model shown in Eq. (2). The

relation between shear stress and shear rate in vacuum

capillary test is shown in Eq. (5). Based on Eqs. (2) and

(5), relations between shear stress and shear rate of 10

binders in the study are shown in Table 5. The values

Table 3 Regression analysis for results of shear rate sweep test

Binder no. Herschel–Bulkley model Carreau model The first Newtonian

region (s-1)Yield stress (Pa) R2 ZSV (Pa s) R2

1 0.08 1.000 184.1 0.963 5.0 9 10-3–23.7

2 0.03 0.999 268.5 0.990 4.9 9 10-4–14.3

3 0.05 0.968 15,620 0.950 5.9 9 10-6–8.7 9 10-2

4 0.03 0.996 8,827 0.985 1.7 9 10-5–4.2 9 10-1

5 0.03 0.997 10,200 0.998 1.1 9 10-5–1.0 9 10-2

6 0.62 0.985 22,665 0.938 3.1 9 10-5–8.6 9 10-2

7 0.79 0.995 38,435 0.959 3.7 9 10-5–5.3 9 10-2

8 0.27 0.963 43,130 0.994 4.0 9 10-5–2.2 9 10-2

9 0.17 0.992 49,360 0.906 2.5 9 10-5–8.3 9 10-2

10 0.81 0.961 73,880 0.999 7.6 9 10-5–2.7 9 10-2

Table 4 Low shear viscosity and LSV to ZSV ratio

Binder no. LSV (Pa s) at specific shear rate (s-1) LSV to ZSV ratio (%) at specific shear rate (s-1)

10-4 10-3 10-2 10-1 10-4 10-3 10-2 10-1

1 899.6 287 202.9 172.9 494.0 157.6 111.4 94.9

2 381.6 259 258.9 250.9 142.1 96.5 96.4 93.4

3 13,490 13,960 16,720 14,930 86.4 89.4 107.0 95.6

4 8,653 9,351 9,327 8,585 107.1 99.2 97.2 89.5

5 10,780 10,080 8,091 3,546 105.2 98.3 78.9 34.6

6 24,430 28,320 20,500 10,550 108.1 125.4 90.7 46.7

7 49,670 43,810 33,380 16,480 128.8 113.6 86.5 42.7

8 38,640 40,360 41,400 20,370 89.6 93.6 96.0 47.2

9 43,520 42,850 47,080 76,840 88.2 86.8 95.4 155.7

10 72,020 71,570 73,410 32,150 106.3 96.9 99.6 51.4

Average – – – – 145.0 105.5 95.8 75.1

Variance – – – – 122.0 21.1 9.1 37.5

Materials and Structures

of shear rate corresponding to capillary viscosity were

calculated by including the shear stress in Eq. (5) into

Eq. (2). Results of shear rate in vacuum capillary test

(cc0) and the minimum of the first Newtonian region

(c0min) are shown in Table 5. The indicator of c0min

represents the minimum shear rate to overcome yield

stress of asphalt binders in the study. As shown, for all

binders in the study except No. 4, the values of cc0 vary

in the range of 1.1 9 10-6–3.1 9 10-3 s-1, which are

0.04–0.99 time the value of c0min. For No. 6, No. 7 and

No. 9 binders, whose capillary viscosity is higher than

1 9 105 Pa s, the values of cc0 are in the range of

1.1 9 10-6–4.4 9 10-6 s-1, which are 0.04–0.14

time the value of c0min. The results indicate that the

100

1000

10000

100000

1000000

1 2 3 4 5 6 7 8 9 10

Vis

cosi

ty (

Pa·

s)

Binder Number

Low shear viscosity at 0.01 1/s

Zero shear viscosity

Capillary viscosity

Fig. 3 Results of LSV0.01,

ZSV and capillary viscosity

Table 5 Shear rate of capillary viscosity

Binder no. Eq. (2) for each binder Eq. (5) for each binder c0c (s-1) c0min (s-1) Ratio of c0c to c0min (s-1)

1 sc ¼ 0:08þ 156:9 c0c� �0:960 sc = 222.6c0c 3.1 9 10-3 5.0 9 10-3 0.62

2 sc ¼ 0:03þ 246:9 c0c� �0:996 sc = 326.0c0c 3.9 9 10-4 4.9 9 10-4 0.80

3 sc ¼ 0:05þ 20501:8 c0c� �1:052 sc = 25,050c0c 3.6 9 10-6 5.9 9 10-6 0.61

4 sc ¼ 0:03þ 11475:4 c0c� �1:055 sc = 7,225c0c 3.7 9 10-5 1.7 9 10-5 2.18

5 sc ¼ 0:03þ 7672:1 c0c� �0:964 sc = 18,076c0c 5.3 9 10-6 1.1 9 10-5 0.48

6 sc ¼ 0:62þ 18000:0 c0c� �0:989 sc = 160,320c0c 4.4 9 10-6 3.1 9 10-5 0.14

7 sc ¼ 0:79þ 29821:3 c0c� �0:975 sc = 337,617c0c 3.0 9 10-6 3.7 9 10-5 0.08

8 sc ¼ 0:27þ 16033:3 c0c� �0:881 sc = 47,152c0c 3.1 9 10-5 4.0 9 10-5 0.78

9 sc ¼ 0:17þ 48291:8 c0c� �1:017 sc = 198,066c0c 1.1 9 10-6 2.5 9 10-5 0.04

10 sc ¼ 0:81þ 56965:3 c0c� �0:964 sc = 91,072c0c 7.5 9 10-5 7.6 9 10-5 0.99

Table 6 Comparison of viscosity test methods

Aspects for

comparison

Shear rate

sweep test

Simplified shear

rate sweep test

Loading mode Steady flow Steady flow

Shear rate range 1.25 9 10-6–

1.25 9 103 s-10.001–0.1 s-1

No. of data points

collected

45 10

Time 60–90 min 10–15 min

Indicators ZSV LSV0.01

Data analysis

method

Model fitting Linear

interpolation

Repeatability CV 1.3–8.3 % CV 2.2–8.5 %

Materials and Structures

shear rate provided by the pressure of vacuum

capillary viscometer test was not high enough to

overcome the yield stress of HVABs. The results may

provide an explanation for the phenomenon that the

values of capillary viscosity were 3.0–7.8 times higher

than ZSV in the study. Based on these results, it can be

concluded that vacuum capillary viscosity test is not

suitable for viscosity evaluating of HVABs, as capil-

lary viscosity of HVABs is significant higher than

ZSV and the shear rate in vacuum capillary viscosity

test is not high enough to overcome the yield stress of

HVABs.

(a) Relation between TR&B ηc and DS

(c) Relation between G*/sinδ 0.1 and DS

and DS (b) Relation between

and DS (d) Relation between Jnr

(e) Relation between ZSV and DS (f) Relation between LSV0.01 and DS

y = 8.892×10-7x5.178

R² = 0.920

α = 0.0024

0

2000

4000

6000

8000

10000

12000

14000

DS

(P

asse

s/m

m)

TR&B

y = 1121.4ln(x) - 5687.8

R² = 0.897

α = 0.0042

0

2000

4000

6000

8000

10000

12000

14000

DS

(P

asse

s/m

m)

ηc (Pa·s)

y = 162.032 x1.486

R² = 0.830

α = 0.0115

0

2000

4000

6000

8000

10000

12000

14000

DS

(P

asse

s/m

m)

G*/sinδ (kPa)

y = 1114.4x-0.789

R² = 0.940

α = 0.0014

0

2000

4000

6000

8000

10000

12000

14000

DS

(P

asse

s/m

m)

Jnr0.1 (kPa-1)

y = 10.098x0.657

R² = 0.954

α = 0.0008

0

2000

4000

6000

8000

10000

12000

14000

DS

(P

asse

s/m

m)

ZSV (Pa•s)

y = 8.708 x0.677

R² = 0.939

α = 0.0014

0

2000

4000

6000

8000

10000

12000

14000

20 40 60 80 100 0 100000 200000 300000 400000

0 10 20 0.000 2.000 4.000 6.000

0 20000 40000 60000 0 20000 40000 60000

DS

(P

asse

s/m

m)

LSV0.01 (Pa•s)

Fig. 4 Relation between

binders’ indicators and

dynamic stability of porous

asphalt. Created by ‘‘Excel

2010’’

Materials and Structures

sc ¼ c0c � gc ð5Þ

where sc is shear stress in vacuum capillary viscosity

test, Pa; cc0 is shear rate corresponding to capillary

viscosity, s-1; gc is capillary viscosity, Pa s.

4.4 Simplified shear rate sweep test

The shear rate sweep test is time consuming and data

fitting by Cross or Carreau model is required to estimate

ZSV, which is not practical for routine viscosity evalu-

ation of HVABs. A simplified shear rate sweep test was

proposed in the study. Both the shear rate sweep test and

simplified shear rate sweep test are shown in Table 6. As

shown, both measurements are conducted by rheometer in

steady flow mode. The shear rate range of simplified shear

rate sweep test is 0.001–0.1 s-1, which is two-ninths of

the shear rate range performed in the study. The simplified

shear rate sweep test collects 5 data points per decade. As

the reduction of shear rate range, the simplified test lasts

for 10–15 min, resulting in a time saving of 45–80 min

per trial. Linear interpolation is used for the determination

of LSV0.01 in the simplified shear rate sweep test based on

viscosity values of two nearest shear rates to 0.01 s-1.

Compared to model fitting method for the determination

of ZSV, specific data analysis software such as Rheology

Advantage provided by TA Instruments is not required for

the simplified shear rate sweep test. Both of the test

methods show similar repeatability in the study. The

coefficient of variation (CV) of LSV0.01 and ZSV is

2.2–8.5 and 1.3–8.3 % respectively.

4.5 Verification of low shear viscosity

Porous asphalt with the nominal maximum aggregate

size of 13.2 mm was designed for wheel tracking test.

Results of DS are shown in Table 1. Linear, power,

exponential and logarithmic functions were compared

to find the regressions between binders’ indicators and

DS of porous asphalt with the maximal correlation

coefficient. Relation between binders’ indicators and

DS of porous asphalt are shown in Fig. 4, in which R2 is

squared correlation coefficient and a is significance F.

As shown, ZSV, low shear viscosity at 0.01 s-1

(LSV0.01) and non-recoverable creep compliance at

0.1 kPa (Jnr0.1) at 60 �C exhibit good correlation with

DS of porous asphalt, with R2 no less than 0.939 and ano greater than 0.0014. Softening point (TR&B) shows

fair correlation with DS of porous asphalt, with R2 of

0.920. For capillary viscosity (gc) and G*/sind, the

values of R2 are 0.897 and 0.830, respectively. In

conclusion, the indicators of ZSV, LSV0.01 and Jnr0.1

exhibited better correlation with DS of porous asphalt

than the other indicators in the study.

5 Conclusions

In the study, 6 HVABs were tested in the laboratory. The

results were compared to neat binders, SBS binder and

high modulus asphalt binder. The viscosity indicators

including ZSV, LSV0.01 and capillary viscosity were

evaluated. The analysis of results allowed the following

statements to be made:

1. Asphalt binders exhibited yield pseudo-plastic

fluid behavior at 60 �C. For HVABs with ZSV

higher than 2 9 104 Pa s, the yield stress was

0.2–0.8 Pa and the overlapped range of the first

Newtonian region was 8 9 10-5–2 9 10-2 s-1.

2. The vacuum capillary viscosity test was not

suitable for viscosity evaluating of HVABs at

60 �C. Capillary viscosity of HVABs can be 3–8

times higher than ZSV and the shear rate in

vacuum capillary viscosity test was not high

enough to overcome the yield stress of HVABs.

3. The simplified shear rate sweep test provided a

simple, fast and reliable measurement of LSV0.01.

The test was performed by rheometer in steady

flow mode in the shear rate range of 0.001–0.1 s-1

and five shear rate levels were applied per decade

with equidifferent progressive increase in loga-

rithmic coordinates.

4. LSV0.01 was suggested as the viscosity evaluating

indicator of HVABs, which exhibited both close

values to ZSV and significant correlation with

rutting resistance of porous asphalt.

Acknowledgments Professor Weimin Lyu provided useful

discussion and advice for the research, whose help is gratefully

acknowledged. The authors would also like to acknowledge Mr.

Xurong Ma who performed vacuum capillary viscometer test for

the research.

References

1. ASTM Standard D04 (2008) Road and paving materials.

ASTM International, West Conshohocken. doi:10.1520/

D7175-08

Materials and Structures

2. ASTM Standard D04 (2010) Road and paving materials.

ASTM International, West Conshohocken. doi:10.1520/

D2171-10

3. ASTM Standard D04 (2010) Road and paving materials.

ASTM International, West Conshohocken. doi:10.1520/

D7405-10A

4. Barnes HA, Hutton JF, Walters K (1989) An introduction to

rheology, vol 3. Elsevier, Amsterdam

5. CEN/TS 15324 (2008) Bitumen and bituminous binders:

determination of equiviscous temperature based on low

shear viscosity using a dynamic shear rheometer in low

frequency oscillation mode. European Committee for

Standardization, London

6. CEN/TS 15325 (2008) Bitumen and bituminous binders:

determination of zero shear viscosity (ZSV) using a shear

stress rheometer in creep mode. European Committee for

Standardization, London

7. De Visscher J, Vanelstraete A (2004) Practical test methods

for measuring the zero shear viscosity of bituminous bind-

ers. Mater Struct 37(5):360–364

8. Desmazes C, Lecomte M, Lesueur D, Phillips M (2000) A

protocol for reliable measurement of zero-shear-viscosity in

order to evaluate the anti-rutting performance of binders. In:

Proceedings of 2nd Eurasphalt & Eurobitume Congress,

Barcelona

9. Izumoto R (2000) Asphalt modifier, process for producing

modified asphalt, and process for producing road pavement

material, publication no. WO2000046304. World Intellec-

tual Property Organization, Geneva

10. Japan Road Association (1996) Technical manual of porous

asphalt pavement. Maruzen Publishing Co., Ltd., Tokyo

11. JMAAS-01 (2007) Japan Modified Asphalt Association

Standard. Japan Modified Asphalt Association, Tokyo

12. Larson RG (1999) The structure and rheology of complex

fluids, vol 2. Oxford University Press, New York

13. Li L-H, Geng H, Sun Y-N (2010) Evaluation method and

indicator for viscosity of high-viscosity asphalt. J Constr

Build Mater 13(3):352–362

14. Meng Y-J, Zhang X-N, Jia J (2008) Research on zero shear

viscosity of asphalt based on different loading modes.

J Traffic Transp Eng 8(4):35–38

15. Nakanishi H (2002) Study on improvement in durability of

function for porous asphalt pavement. Guangxi Commun

Sci Technol 27(102):7–12

16. Research Institute of Highway Ministry of Transport (2004)

Technical specifications for construction of highway asphalt

pavements. Ministry of Transport of People’s Republic of

China, Beijing

17. Research Institute of Highway Ministry of Transport (2011)

Standard test methods of bitumen and bituminous mixtures

for highway engineering. Ministry of Transport of People’s

Republic of China, Beijing

18. Shanghai Municipal Engineering Design Institute (Group)

Co., Ltd. (2010) Technical code for drainage asphalt pave-

ment of road. Shanghai Urban Construction and Commu-

nications Commission, Shanghai

19. Sybilski D (1993) Non-Newtonian viscosity of polymer-

modified bitumens. Mater Struct 26(1):15–23

20. Sybilski D (1996) Zero-shear viscosity of bituminous binder

and its relation to bituminous mixture’s rutting resistance.

Transp Res Rec 1535(1):15–21

21. Wang S, Ma Q, Li J (2012) Study and application progress

of high viscosity modified asphalt used in porous pavement.

Pet Asph 26(1):1–7

Materials and Structures