Study on Basic Properties And High-temperature
Performance of Rice-husk-ash-modified-asphalt
Jun Cai1,a, Yongjie Xue1,b, Li Wan1,c,Shaopeng Wu1,d, Kim Jenkins2,e
1 State Key laboratory of Silicate Materials for Architectures, Wuhan University of Technology,
Wuhan, 430070, China
2University of Stellenbosch, Moderator, South Africa
[email protected], [email protected], [email protected], [email protected], [email protected]
Key word: rice-husk-ash, modified asphalt, basic properties, DSR
Abstract: Currently, many inorganic materials are investigated for modifying asphalts, but biomass
ash is rarely applied to the modification of asphalt. In this present work, rice-husk-ash, as a
representative of the biomass ashes, was added as a modifier to evaluate the related performance.
The result showed that the basic performance, aging resistance, and high-temperature performance
of modified asphalt has been improved, which proves that biomass ash can be used as an asphalt
modifier for resource reuse.
Introduction
Since transportation been great developed, requirements on asphalt mixes performance can never be
so strict than before. To meet these high requirements, lots of pavement materials have been
investigated [1]
. All kinds of modified asphalt and modified asphalt mixture have been used widely
for their well using quality; and new additive and modified asphalt mixture are also emerged at
times[2-5].
Among these, inorganic modified materials are given us a deep impression. Yanni Bao et
al investigated the morphological and rheological changes of the diatomite-modified asphalt
mixtures blends and asphalt concrete[6]
; Fang C et al Concentrated on the Organic montmorillonite /
PE composite modified asphalt which softening point of the modified asphalt, significantly improve
the ductility, high temperature stability, low temperature cracking, deformation performance has
been significantly improved[7]
; Zhanping You evaluated and analysis the effect of nanoclay on the
improvement of the modified asphalt[8]
.
It can be found, from the reviews above, that most of inorganic materials modifying asphalt
focused on those materials well recognized, few of them focused on the new inorganic mineral
modifiers.
Biomass refers to the use of air, water, land and other various organisms through photosynthesis,
that all of life can grow organic material known as biomass [9]
. And many crops, crop waste, wood,
wood waste and animal dung used for other purposes with little regard to the direction of
application to modified asphalt .Some results show that most biomass ashes have many asphalt
beneficial elements [9]
, Therefore, in this paper, the author tries to test Basic Properties and
high-temperature performance of rice-husk-ash-modified-asphalt, to find how biomass ash benefits
the asphalt. To facilitate the study, we selected the single gray as research object, and X-ray
Applied Mechanics and Materials Vols. 333-335 (2013) pp 1889-1894Online available since 2013/Jul/15 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMM.333-335.1889
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fluorescence spectrometer (XRF), Scanning Electron Microscope (SEM), Dynamic Shear
Rheometer (DSR) et al are employed to evaluate the change in the basic performance and high
temperature performance of the modified asphalt.
Experimental
2.1 Raw materials
2.1.1 Matrix asphalt
PJ 70# matrix asphalt was used in this experiment, and the physical properties of the asphalt were
listed in Table 1.
Table 1 Physical properties of asphalt 70#
Physical properties Technical requirements Values
15°C / 20.1
Penetration/0.1mm 25°C 60—80 73.1
30°C / 121.5
Softening point /°C / ﹥44 47
Ductility /mm 15°C ﹥1000 ﹥1600
5°C / 455
rice-husk-ash 2000×××× rice-husk-ash 10000××××
Finely ground rice-husk-ash 2000×××× Finely ground rice-husk-ash 10000××××
Fig. 1 Microscopic surface morphology of rice-husk-ash by SEM
1890 Measurement Technology and Engineering Researches in Industry
2.1.2 Rice-husk-ash
The rice-husk-ash that used in the experiment is brunt rice husk from power station. Firstly, they
were put at 800 degrees Celsius for heat treatment, then grinded by Variable Frequency planetary
ball mill (a grinding machine made by the XQM-4L Nanjing KeXi Laboratory Instrument Research
Institute) for a 0.075mm (200 mesh) filter, with the pass ratio being 85%. The main component of
rice-husk-ash is showed in Table 2, and the microscopic surface morphology of rice-husk-ash SEM
is showed in Figures 1. Table 2 shows that with high content of SiO2, and the content of R2O3 is less
than 5%, so the main component of rice-husk-ash are quite similar to the chemical composition of
some parts Diatomaceous earth—a modifier used in modification of asphalt. Figure 1 showed the
rice-husk-ash is fine and also has a loose and porous structure, all of which bring it strong
adsorption to asphalt.
Table2 Main component of rice-husk-ash
Component SiO2 Fe2O3 Al2O3 MgO K2O P2O5 CaO others
Content（%）
85.93 1.12 2.2 0.73 3.76 1.37 2.87 2.02
2.2 The Preparation of Rice-husk-ash-modified Asphalt
The sample, certain amount of melt 70 # matrix asphalt was poured into a modification barrel, when
the Oil-bath heated to 160-170 °C the rice-husk-ash was added to the matrix asphalt at
concentrations of 5%, 10%, 15% and 20% by the weight of control asphalt, respectively. The
high-speed stirrer was maintained at 200r/min for 45mins, to ensure a well blend of the
rice-husk-ash and in the asphalt. Therefore, the rice-husk-ash-modified-asphalt（RMA）was
prepared.
2.3 The performance test of RMA
The performance test is based on the Standard Test Methods of Bitumen and Bituminous Mixture
for Highway Engineering to get the result. The matrix asphalt and modified asphalt were all tasted
their penetration, softening point, ductility and high-temperature performance
3. Results and discussion
3.1 Basic properties of RMA
Table 3 shows the physical properties of modified asphalt. It is clear that with the mount of
rice-husk-ash increasing, penetration decreases and softening point increases, hardness increases.
The high-temperature behavior of the modified asphalt is improved. On the other hand, with the
mount of rice-husk-ash increasing, ductility of the modified asphalt decreasing, rice-husk-ash has
certain influence on asphalt’s low-temperature behavior, but ductility still meets the requirement in
the Standard Test Methods of Bitumen and Bituminous Mixture for Highway Engineering.
Table 3 Physical properties of modified asphalt binder
Modified asphalt Physical properties 5 wt% 10 wt% 15 wt% 20 wt%
15°C 18.6 18.9 17 15.6
Penetration/0.1mm 25°C 54.6 50.9 48.7 45.6
30°C 89.6 86.9 72.3 60.3
Softening point /°C / 47.1 49.5 49 49.9
Ductility /mm 15°C ﹥1600 1426 1193 869
5°C 318 223 145 133
Applied Mechanics and Materials Vols. 333-335 1891
3.2 Ageing Property of RMA
Table 4 and Table 5 Matrix show the results of Thin Film Oven Test（TFOT）and Pressurized Aging
Vessel（PAV） of matrix asphalt and modified asphalt. The penetration and ductility decreased while
softening point increased for both of matrix asphalt and modified asphalt. Compared to matrix
asphalt, penetration, ductility of modified asphalt decreased slightly and softening point increased
slowly which proved that the more rice-husk-ash was added into asphalt, the better aging resistance
performance was observed. The detailed data were showed in Fig. 2. From Fig. 2 we can also find
that the content of rice-husk-ash during 10-15% reflects better aging resistance performance.
The rice-husk-ash’s ageing resistance was better than that of asphalt, and porosity of
rice-husk-ash could protect the asphalt inside from the damage caused by high temperature. All of
these may explain the ageing resistance improvement of the modified asphalt. Therefore, the ageing
resistance of the modified asphalt is improved with the mount of rice-husk-ash increasing.
Table 4 Physical properties of 70# and modified asphalt binder after TFOT
Modified asphalt Physical properties 0wt% 5 wt% 10 wt% 15 wt% 20 wt% 15°C 16 12.8 13.3 13.3 11.5
Penetration/0.1mm 25°C 48.7 40.1 40.6 38.9 33 30°C 94.3 65.1 67.1 65.6 60.6
Softening point /°C / 52.9 51.2 53 54 56.1
Ductility /mm 15°C 540 473 396 351 287
5°C 137 140 115 98 64
Table 5 Physical properties of 70# and modified asphalt binder after PAV
Modified asphalt Physical properties 0wt% 5 wt% 10 wt% 15 wt% 20 wt% 15°C 11.6 9.5 10 9.7 9.3
Penetration/0.1mm 25°C 30.3 28.5 28.2 27.5 23.8 30°C 49.5 46.3 47 46 41.3
Softening point /°C / 58.8 57.3 58.8 59.2 60.8
Ductility /mm 15°C 152 134 128 113 113
5°C 51 55 54 45 35
3.3 DSR for High-temperature Performance
DSR was made to evaluate the high-temperature performance of modified asphalt. The tested
temperatures ranged from 30 to 80°C, at a 10rad/s of DSR loading frequency with a 25mm rotor.
The result shows in Figure 3.
Compared to matrix asphalt, both complex modulus and rutting factor were improved with a
increase of rice-husk-ash。It proved that modified asphalt showed a better high-temperature
performance. Greater improvement was gained after rice-husk-ash beyond 15%.
The possible explanation may be that the particles in asphalt increased with the increasing of
rice-husk-ash, which bore a part of the shearing force, resulting in a rise in modulus and rutting
factor. On the other hand, since the rice-hull-ash is porous, its ability to absorb asphalt lead to
1892 Measurement Technology and Engineering Researches in Industry
decrease of asphalt liquid. When rice-husk-ash was added to a certain extent, its leading role in the
modified asphalt will be reflected, which would greatly improve the high temperature performance
of the modified asphalt.
Fig. 2：Effect of aging on physical properties of 70# and modified asphalt binder
Fig. 3 Effect of contents on G*/sinδ of asphalt binder
0
20
40
60
80
0 wt% 5 wt% 10 wt% 15 wt% 20 wt%
Pe
ne
tra
tio
n r
ati
o [
%]
（（（（a））））Effect of aging on the penetration
of asphalt binder（（（（25°C））））TFOT
PAV
0
2
4
6
8
10
12
14
0 wt% 5 wt% 10 wt%15 wt%20 wt%
So
fte
nin
g p
oin
t in
cre
me
nt
[°C
]
（（（（b））））Effect of aging on the softening
point of asphalt binder
TFOT
PAV
0
20
40
60
80
0 wt% 5 wt% 10 wt%15 wt%20 wt%Re
tain
ed
du
ctil
ity
ra
te [
%]
（（（（c））））Effect of aging on the ductility of asphalt
binder（（（（5°C））））TFOT
PAV
0
50
100
150
200
250
300
350
400
450
30 40 50 60 70 80Co
mp
lex
mo
du
lusG
*(k
Pa
)
Temperature(°C)
20 wt%
15 wt%
10 wt%
5 wt%
0 wt%
100
50,100
100,100
150,100
200,100
250,100
300,100
350,100
400,100
450,100
30 40 50 60 70 80rutt
ing
fa
cto
r G
*/s
inδ
Temperature(°C)
20 wt%
15 wt%
10 wt%
5 wt%
0 wt%
Applied Mechanics and Materials Vols. 333-335 1893
4 Conclusions
(1) Rice-husk-ash had an influence on asphalt, and the penetration and ductility of the modified
asphalt decreased, while softening point increased. (Ductility still meets the requirement of
application)
(2) The ageing resistance of the modified asphalt is improved with the mount of rice-husk-ash
increasing, and the content of rice-husk-ash during 10-15% reflects obvious effect.
(3) In high-temperature performance testing of modified asphalt through DSR, both complex
modulus and rutting factor are improved, which shows a better high-temperature performance of
modified asphalt.
Acknowledgements
This work was financially supported by international technology cooperation projects of Ministry of
science and technology (2010DFA82490).
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1894 Measurement Technology and Engineering Researches in Industry
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