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International Journal <strong>of</strong> Civil Engineering <strong>and</strong> Building Materials (ISSN 2223-487X) Vol. 2 No.4 2012<br />
© 2012 International Science <strong>and</strong> Engineering Research Center<br />
<strong>Determination</strong> <strong>of</strong> <strong>Mixing</strong> <strong>and</strong> <strong>Compaction</strong> <strong>Temperatures</strong> Shift for Asphalt<br />
Mastic at Different Type <strong>and</strong> Content <strong>of</strong> Mineral Fillers<br />
Aaron D. Mwanza 1,a , Peiwen Hao 1,b <strong>and</strong> Xayasone Xongyonyar 1,c<br />
1 Highway College, Chang’an University, Shaanxi, Xi’an,710064,China<br />
a aaronmwanzad@yahoo.com, b haopw@yahoo.com.cn, c sunyansong_xay@hotmail.com<br />
Keywords: Mineral Filler, Asphalt Mastic, Viscosity, Viscometer, Plain Asphalt.<br />
Abstract. The fundamental mixing <strong>and</strong> compaction temperatures for asphalt mixtures are determined<br />
by equi-viscous lines 0.170±0.02 Pa·s <strong>and</strong> 0.280±0.03 Pa·s from unmodified asphalt binder<br />
viscosity-temperature charts. It is obvious that at mixing <strong>and</strong> compaction temperatures, asphalt<br />
binders do not exist alone, but are admixed in one way or another with mineral matter varying<br />
immensely in mineralogical <strong>and</strong> physical properties. The mineral filler or dust suspensions in asphalt<br />
binder form asphalt mastic, which act as a matrix for coating the larger mineral aggregates. It is from<br />
this background that the viscosity <strong>of</strong> the asphalt mastic, rather than that <strong>of</strong> the plain asphalt, should<br />
provide pertinent information on the mixing <strong>and</strong> compaction temperatures <strong>of</strong> asphalt mixture.<br />
Apparent viscosities were tested according to the procedures in ASTM D4402 <strong>and</strong> equivalent<br />
JTJ05-2000 <strong>of</strong> China on various types <strong>of</strong> asphalt mastics. Three different mineral fillers, hydrated<br />
lime, Portl<strong>and</strong> cement <strong>and</strong> pulverized limestone were mixed with plain asphalt binder No-70<br />
(Penetration grade) at dust to binder ratios ranging from 0.0 to 1.5 in ratio increments <strong>of</strong> 0.3% by<br />
weight <strong>of</strong> asphalt. Viscosity was measured using a digital viscometer at 135°C, 165°C, <strong>and</strong> 195°C to<br />
generate data for viscosity temperature charts. Analyses <strong>of</strong> test results show that mastic viscosity is a<br />
well-defined linear function <strong>of</strong> temperature in the coordinates for plain asphalt equi-viscous range.<br />
The filler type, <strong>and</strong> content have significant effects on the relationship between temperature <strong>and</strong><br />
viscosity. Using equi-viscous lines, all asphalt mastics showed a positive shift in the mixing <strong>and</strong><br />
compaction temperatures at different type <strong>and</strong> content <strong>of</strong> filler from the plain asphalt. The shift in the<br />
mixing temperatures recorded at a dust-to-binder ratio <strong>of</strong> 0.6 for hydrated lime is equivalent to 0.722<br />
for Portl<strong>and</strong> cement <strong>and</strong> 0.735 for pulverized limestone respectively.<br />
Introduction<br />
<strong>Mixing</strong> <strong>and</strong> compaction temperatures for asphalt mixtures is determined at elevated temperatures<br />
from plain asphalt viscosity – temperature charts at 0.170±0.02 Pa·s <strong>and</strong> 0.280±0.03 Pa·s [1]. The<br />
measurement concepts are relatively straightforward for unmodified plain binders tested at pumping,<br />
mixing <strong>and</strong> compaction temperatures. These materials are usually newtonian which means that the<br />
measured viscosities are independent <strong>of</strong> the shear rate <strong>and</strong> there is a single, unique value for the<br />
viscosity. It is obvious that at mixing <strong>and</strong> compaction temperatures for asphalt mixtures, asphalt<br />
binders do not exist alone, but are admixed in one way or another with mineral matter varying<br />
immensely in mineralogical <strong>and</strong> physical properties. These fillers are added in the asphalt plant cold<br />
bin as either commercial or baghouse fillers for various resaons such as,solving a problem where an<br />
additive or extender might help,stiffen or extend the asphalt binder,alter the moisture resistance,<br />
workability, compaction <strong>and</strong> temperature sensitivity characteristics <strong>of</strong> the asphalt mixture [1,2].<br />
The mineral filler or dust suspensions in asphalt binder form asphalt mastic, which act as a matrix<br />
for coating the larger mineral aggregates. It is from this background that beside using the plain<br />
asphalt binder to determine asphalt mixtures mixing <strong>and</strong> compaction temperatures, asphalt mastics,<br />
should provide pertinent information on the mixing <strong>and</strong> compaction temperatures <strong>of</strong> asphalt<br />
mixtures. Asphalt mix design procedures have traditionally used equi-viscous temperature ranges for<br />
selecting laboratory mixing <strong>and</strong> compaction temperatures for asphalt mixtures, with the intent <strong>of</strong><br />
normalizing the effect <strong>of</strong> asphalt binder stiffness on mixture volumetric properties. The method stated<br />
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International Journal <strong>of</strong> Civil Engineering <strong>and</strong> Building Materials (ISSN 2223-487X) Vol. 2 No.4 2012<br />
© 2012 International Science <strong>and</strong> Engineering Research Center<br />
in ASTM D 2493 is found suitable as the mastic viscosity is a well-defined linear function <strong>of</strong><br />
temperature in the coordinates for plain asphalt equi-viscous range. With increasing use <strong>of</strong> mineral<br />
fillers in the asphalt paving industry, which incorporates various additives that stiffen binders, this<br />
method can used to predict reasonable asphalt mixtures mixing <strong>and</strong> compaction temperatures shift<br />
from that <strong>of</strong> neat binders. A reasonable determination <strong>of</strong> the mixing <strong>and</strong> compaction temperature<br />
master curve from asphalt mastics is important to avoid construction problems, due to heat damage <strong>of</strong><br />
asphalt, <strong>and</strong> lead to the release <strong>of</strong> unacceptable levels <strong>of</strong> “blue smoke” <strong>and</strong> cause difficulties in<br />
compaction.<br />
Description <strong>of</strong> Materials <strong>and</strong> Experimental Procedures<br />
Asphalt cement. The source <strong>of</strong> the plain asphalt binder as well as mineral fillers is from Jiangsu<br />
production plant in China <strong>and</strong> properties <strong>of</strong> No. 70 petroleum asphalt binder are shown in Tab.1. All<br />
the asphalt binder tests were done in accordance with the testing procedures as outlined in JTJ 052-<br />
2000 [3]. The asphalt binder was tested before conducting experiments for this research to verify<br />
conformity with the st<strong>and</strong>ard specifications for use <strong>of</strong> such materials as outlined in specification JTG<br />
F40-2004 [4]. It can be seen from the test results that the asphalt binder met the requirements for No.<br />
70 penetration grade asphalt binder. It must be mentioned that no characterization tests were done on<br />
the commercial mineral fillers supplied for the purpose <strong>of</strong> this project. However, all the fillers are as a<br />
result <strong>of</strong> the calcination process that occurs <strong>and</strong> due to the presence <strong>of</strong> calcium content in these fillers,<br />
there is a possibility that a chemical reaction takes place with plain asphalt <strong>and</strong> results in certain<br />
properties <strong>of</strong> the asphalt-filler mastic.<br />
Table 1 Properties <strong>of</strong> No. 70 petroleum asphalt binder<br />
Test Unit St<strong>and</strong>ard Tested Value<br />
Penetration (25°C, 5s , 100g ) 0.1 mm 60~80 71<br />
Penetration index PI - -1.8~1.0 0.084<br />
S<strong>of</strong>tening point (R&B) min °C 43~44 44.8<br />
Ductility at 15°C min cm 100 >100<br />
Wax content max % 3.0 -<br />
Flash point max °C 260 310<br />
Solubility in trichloroethylene<br />
% 99.5 -<br />
min<br />
Density (15°C ) g/cm 3 Actual 1.005<br />
After TFOT<br />
Change in mass max % ±0.8 - 0.36<br />
Penetration ( % <strong>of</strong> original) % 58 59.6<br />
Retained ductility 15°C min cm 15 -<br />
Testing procedures. Six dust to binder ratio specimens were prepared in the laboratory for use with<br />
each mineral filler. The dust to binder ratios ranged from 0.0 up to 1.5 in ratio increments <strong>of</strong> 0.3 by<br />
weight <strong>of</strong> asphalt. A brookfield programmable viscometer DV-II was used to test for viscosity at 135,<br />
165, <strong>and</strong> 195°C per dust content [5]. The steps <strong>and</strong> procedures as outlined in ASTM D4402 test No.<br />
TP48 <strong>and</strong> JTJ 052-2000 <strong>of</strong> China, test No. T 0625 were used. Two brookfield specimen volumes <strong>of</strong><br />
8ml <strong>and</strong> 10ml were prepared for testing with SC4-21 <strong>and</strong> SC4-27 spindles respectively. The 8ml<br />
brookfield specimens were prepared for testing at 0.0 <strong>and</strong> 0.3 dust to binder ratio contents <strong>and</strong> 10ml<br />
for 0.6, 0.9, 1.2, <strong>and</strong> 1.5 respectively. The asphalt filler mastic samples were produced by adding the<br />
correct weight per sample to the heated plain asphalt. The mineral fillers prior to mixing were heated<br />
to 100°C for 24hrs to ensure moisture free particle surfaces. The mixing time was restricted to 15<br />
minutes to minimise further hardening due to the short aging process <strong>and</strong> was done in the brookfield<br />
viscometer cylinders <strong>of</strong> either 8ml or 10ml based on the mineral filler to binder mix ratio.<br />
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International Journal <strong>of</strong> Civil Engineering <strong>and</strong> Building Materials (ISSN 2223-487X) Vol. 2 No.4 2012<br />
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Test Results <strong>and</strong> Analysis<br />
Viscosity. Three asphalt mastic specimen per dust content were tested at three different temperatures<br />
135, 165, <strong>and</strong> 195°C <strong>and</strong> the average viscosity per testing temperature at a specific dust content was<br />
recorded in centipoises as the viscosity <strong>of</strong> the asphalt mastic specimen at a test temperature <strong>and</strong> dust<br />
content. The order <strong>of</strong> testing was from lowest mineral filler content <strong>and</strong> temperature to highest. A<br />
linear relationship between viscosity (log-log scale) <strong>and</strong> temperature is established for each mineral<br />
filler dust to binder ratio content using the equation below.<br />
V i = A + VTS(<br />
Ti<br />
)<br />
(1)<br />
Where V is viscosity in (Pa·s), A is the regression intercept,Tiis temperature <strong>of</strong> interest, (°C) <strong>and</strong><br />
VTS is the regression slope <strong>of</strong> viscosity temperature susceptibility.Using least squares regression<br />
method, the linear eq. 1 is established per dust to binder content as shown in table 2. The figures<br />
generated for each mineral filler are shown in figures 1 to 3. At 0.170±0.02 Pa·s <strong>and</strong> 0.280±0.03<br />
Pa·s equi-viscous lines, the temperatures for asphalt mixtures mixing <strong>and</strong> compaction are established<br />
at any dust to binder ratio content for each specific mineral filler as shown in the figures below.<br />
Depending on the type <strong>and</strong> content <strong>of</strong> mineral filler recommended for use with No.70 (Penetration<br />
grade), the required asphalt mixtures mixing <strong>and</strong> compaction temperatures can be read <strong>of</strong>f from the<br />
particular asphalt mastic graph. It should be noted that a linear regression equation for mineral filler<br />
to binder ratio <strong>of</strong> 1.5 for hydrated lime is missing because the mixture at such a high content <strong>of</strong><br />
hydrated lime was too stiff to work. Hydrated lime has a higher specific gravity than other mineral<br />
fillers hence the method based on weight other than volume <strong>of</strong> mineral filler proved to work well for<br />
low specific gravity fillers such as limestone <strong>and</strong> Portl<strong>and</strong> cement.<br />
Filler to<br />
binder<br />
ratio<br />
0<br />
0.3<br />
0.6<br />
0.9<br />
1.2<br />
1.5<br />
Table 2 Viscosity at different type <strong>and</strong> content <strong>of</strong> mineral fillers<br />
Test<br />
Temp<br />
. o Viscosity (Pa.s) Viscosity equation Vi = A + VTS(Ti)<br />
C Hydrated<br />
Lime<br />
Lime<br />
stone<br />
Portl<strong>and</strong><br />
cement<br />
Hydrated Lime Limestone Portl<strong>and</strong> Cement<br />
135 0.42 0.42 0.42<br />
165 0.11 0.11 0.11 Vi=1.24-0.006Ti Vi=1.24-0.006Ti Vi=1.24-0.006Ti<br />
195 0.04 0.04 0.04<br />
135 0.9 0.59 0.6<br />
165 0.2 0.16 0.2 Vi=2.6-0.0133Ti Vi=1.73-0.0088Ti Vi=1.68-0.0083Ti<br />
195 0.1 0.06 0.1<br />
135 3.1 0.85 1.0<br />
165 0.8 0.23 0.3 Vi=9.1-0.0467Ti Vi=2.48-0.0127Ti Vi=2.94-0.015Ti<br />
195 0.3 0.09 0.1<br />
135 14 1.45 2.1<br />
165 3.2 0.37 0.5 Vi=41.58-0.215Ti Vi=4.26-0.0218Ti Vi=6.16-0.0317Ti<br />
195 1.1 0.14 0.2<br />
135 27.4 2.41 4.6<br />
165 5.4 0.59 1.1 Vi=82.18-0.428Ti Vi=7.12-0.0367Ti Vi=13.58-0.07Ti<br />
195 1.7 0.21 0.4<br />
135 - 3.69 12.8<br />
165 - 0.86 3.0<br />
- Vi=10.94-0.0565Ti Vi=37.81-0.195Ti<br />
195 - 0.3 1.1<br />
161
Viscosity (Pa·s)<br />
Viscosity (Pa·s)<br />
International Journal <strong>of</strong> Civil Engineering <strong>and</strong> Building Materials (ISSN 2223-487X) Vol. 2 No.4 2012<br />
© 2012 International Science <strong>and</strong> Engineering Research Center<br />
100.00<br />
10.00<br />
1.00<br />
0.28<br />
0.17<br />
0.10<br />
0.01<br />
100.00<br />
10.00<br />
1.00<br />
0.28<br />
0.17<br />
0.10<br />
0.01<br />
0.28±0.03 Viscosity lines<br />
0.17±0.02 Viscosity lines<br />
125 135 145 155 165 175 185 195 205<br />
Temperature (°C)<br />
Fig. 1 Viscosity versus temperature for Portl<strong>and</strong> cement <strong>and</strong> No.70 petroleum<br />
0.28±0.03 Viscosity lines<br />
0.17±0.02 Viscosity lines<br />
162<br />
0.3 dust to binder ratio<br />
0.6 dust to binder ratio<br />
0.9 dust to binder ratio<br />
1.2 dust to binder ratio<br />
1.5 dust to binder ratio<br />
0.0 dust to binder ratio<br />
<strong>Compaction</strong> range <strong>Mixing</strong> range<br />
0.3 dust to binder ratio<br />
0.6 dust to binder ratio<br />
0.9 dust to binder ratio<br />
1.2 dust to binder ratio<br />
0.0 dust to binder ratio<br />
<strong>Compaction</strong> range <strong>Mixing</strong> range<br />
125 135 145 155 165 175 185 195 205<br />
Temperature (°C)<br />
Fig. 2 Viscosity versus temperature for hydrated lime <strong>and</strong> No.70 petroleum
Viscosity (Pa·s)<br />
10.00<br />
1.00<br />
0.28<br />
0.1<br />
0.10<br />
International Journal <strong>of</strong> Civil Engineering <strong>and</strong> Building Materials (ISSN 2223-487X) Vol. 2 No.4 2012<br />
© 2012 International Science <strong>and</strong> Engineering Research Center<br />
0.28±0.03 Viscosity lines<br />
0.17±0.02 Viscosity lines<br />
0.01<br />
125 135 145 155 165 175 185 195 205<br />
Temperature (°C)<br />
Fig. 3 Viscosity versus temperature for limestone <strong>and</strong> No.70 petroleum<br />
163<br />
0 dust to binder ratio<br />
<strong>Compaction</strong> range <strong>Mixing</strong> range<br />
0.3 dust to binder ratio<br />
0.6 dust to binder ratio<br />
0.9 dust to binder ratio<br />
1.2 dust to binder ratio<br />
1.5 dust to binder ratio<br />
<strong>Determination</strong> <strong>of</strong> asphalt mixtures compaction <strong>and</strong> mixing temperatures. Asphalt mixtures<br />
mixing <strong>and</strong> compaction temperatures are determined at elevated temperatures from plain asphalt<br />
viscosity – temperature charts at equiviscous lines 0.170±0.02 Pa·s <strong>and</strong> 0.280±0.03 Pa·s. The<br />
measurement concepts can be extended to asphalt mastics because the viscosity is a well defined<br />
function <strong>of</strong> temperature <strong>and</strong> mineral filler to binder ratio content within the cordinates defined in the<br />
method stated in ASTM D 2493 for unmodified binders in the equi-viscous range [5]. A reasonable<br />
determination <strong>of</strong> the asphalt mixtures mixing <strong>and</strong> compaction temperature master curve from asphalt<br />
mastics viscosity data is important to avoid construction problems, due to heat damage <strong>of</strong> asphalt as<br />
well as oxidation if mixed at excessive temperatures, <strong>and</strong> lead to the release <strong>of</strong> unacceptable levels <strong>of</strong><br />
“blue smoke” <strong>and</strong> cause difficulties in compaction. Using viscosity data generated for each type <strong>and</strong><br />
content <strong>of</strong> mineral filler, viscosity-temperature graphs are developed for each mineral filler <strong>and</strong><br />
mixing <strong>and</strong> compaction temperature values read <strong>of</strong>f at each mineral filler content based on<br />
0.170±0.02 Pa·s <strong>and</strong> 0.280±0.03 Pa·s. Equi-viscous lines. Fig. 4 shows the mixing <strong>and</strong> compaction<br />
temperature master curves developed from viscosity data <strong>of</strong> the three mineral fillers. Depending on<br />
the type <strong>and</strong> content <strong>of</strong> mineral filler recommended for use with No.70 (Penetration grade) bitumen,<br />
the required asphalt mixtures mixing <strong>and</strong> compaction temperatures can be read <strong>of</strong>f from the graph.<br />
Asphalt cements within the same penetration grade would produce similar asphalt mixtures mixing<br />
<strong>and</strong> compaction temperatures with the same binder type but a lower grade mixed with mineral fillers<br />
determined using the equi-viscous concept. Viscosity - temperature measurements concept can also<br />
provide useful data for temperature susceptibility <strong>of</strong> asphalt cements although different methods are<br />
available to evaluate temperature susceptibility <strong>of</strong> asphalt cements, furthermore temperature indexes<br />
vary <strong>and</strong> depend on the temperature range selected for the calculation <strong>of</strong> such indexes.<br />
Temperature-Viscosity susceptibility is commonly used, because <strong>of</strong> its universality <strong>and</strong> fundamental<br />
nature, <strong>and</strong> is preferred over the empirical methods utilizing either penetration measurements or<br />
penetration <strong>and</strong> viscosity measurements at different temperatures. The interaction between filler<br />
particles <strong>and</strong> the asphalt can be viewed in two ways: physical <strong>and</strong> chemical interaction. Physical<br />
interaction between fillers <strong>and</strong> asphalt refers to formation <strong>of</strong> stiffened matrix. In chemical interaction,<br />
certain fillers might be an active material <strong>and</strong> possibly react with the asphalt thereby altering the<br />
property <strong>of</strong> the asphalt filler mastic [6,7].
<strong>Mixing</strong>/<strong>Compaction</strong> temp. o C<br />
250<br />
240<br />
230<br />
220<br />
210<br />
200<br />
190<br />
180<br />
170<br />
160<br />
150<br />
International Journal <strong>of</strong> Civil Engineering <strong>and</strong> Building Materials (ISSN 2223-487X) Vol. 2 No.4 2012<br />
© 2012 International Science <strong>and</strong> Engineering Research Center<br />
Hydrated lime mix.temp<br />
Lime mix.temp<br />
Cement mix.temp<br />
Hydrated lime comp.temp<br />
lime comp.temp<br />
Portl<strong>and</strong> cement comp.temp<br />
Hydrated lime mixing temp.polyline<br />
Hydrated lime com.temp. polyline<br />
Portl<strong>and</strong> cement mix.temp. polyline<br />
Portl<strong>and</strong> cement comp.temp. polyline<br />
Limestone mix.temp. polyline<br />
Limestone comp.temp polyline<br />
140<br />
0 0.3 0.6 0.9 1.2 1.5<br />
Dust to binder ratio<br />
Fig. 4 <strong>Mixing</strong> <strong>and</strong> <strong>Compaction</strong> Chart for No.70 Asphalt Mastic at Different<br />
Filler type <strong>and</strong> Content<br />
Discussion <strong>of</strong> Test Results<br />
Based on the generated results the following is observed:<br />
Viscosity: Viscosity in all mastic samples at same dust content decreases with increasing test<br />
temperature. Viscosity is a well defined linear function <strong>of</strong> increased mineral filler to binder content<br />
<strong>and</strong> temperature. The viscosity follows the behavior <strong>of</strong> plain asphalt at increased temperatures with a<br />
positive shift due to the stiffening effect from mineral fillers. Portl<strong>and</strong> cement <strong>and</strong> limestone mastics<br />
show a similar trend <strong>of</strong> viscosity increase at increased temperature while hydrated lime mastics show<br />
a more significant viscosity response with temperature increase than other mastics. The comparisons<br />
<strong>of</strong> figures 1, 2 <strong>and</strong> 3 reveal that the ranges <strong>of</strong> initial viscosities for asphalt mastic tend to increase<br />
relative to that <strong>of</strong> plain asphalt mastic with increasing testing temperature <strong>and</strong> mineral filler content.<br />
<strong>Mixing</strong> temperature shift: Asphalt mixtures mixing temperature determined from<br />
viscosity-temperature charts at different mineral filler to binder ratio contents using the equi-viscous<br />
line <strong>of</strong> 0.170±0.02 Pa·s, shows an increment <strong>of</strong> 7.7 o C per 0.1% increment <strong>of</strong> hydrated lime <strong>and</strong> 5.3<br />
o o<br />
C per 0.1% increment <strong>of</strong> Portl<strong>and</strong> cement while limestone is 3.4 C per 0.1% from that determined<br />
from a neat binder.<br />
<strong>Compaction</strong> temperature shift: <strong>Compaction</strong> temperatures determined from equi-viscous line <strong>of</strong><br />
0.280±0.03 Pa·s for asphalt mixtures shows an increment <strong>of</strong> 7.9 o C per 0.1% increment <strong>of</strong> hydrated<br />
lime <strong>and</strong> 5.4 o C per 0.1% increment <strong>of</strong> Portl<strong>and</strong> cement while limestone is 3.5 o C per 0.1% from that<br />
determined from a neat binder.<br />
Mineral filler equivalent factors for mixing temperatures: At 0.6 hydrated lime dust to binder ratio<br />
content the effect on mixing temperature increase is equivalent to 0.722 Portl<strong>and</strong> cement <strong>and</strong> 0.735<br />
pulverized lime.<br />
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Mineral filler equivalent factors for compaction temperatures : At 0.6 hydrated lime dust to binder<br />
ratio content the effect on compaction temperature increase is equivalent to 0.706 Portl<strong>and</strong> cement<br />
<strong>and</strong> 0.748 pulverized lime.<br />
Asphalt grades: Asphalts, within a given grade, do not differ substantially in their rheological<br />
properties, however it is advisable to carry out all the conventional binder tests before using these<br />
developed mixing <strong>and</strong> compaction temperature mastics graphs to check for rheological consistency.<br />
In aggregate stockpile, a small amount <strong>of</strong> dust or mineral filler is usually found as a result <strong>of</strong> natural<br />
degradation or as excess fines/dust after the crushing process <strong>of</strong> larger aggregates. For this practical<br />
reason, mineral filler is included in the aggregate gradation <strong>and</strong> the filler also serves to give a<br />
continuous size representation in aggregate gradation. However, mineral filler exerts a significant<br />
effect on the characteristics <strong>and</strong> performance <strong>of</strong> asphalt mixtures, such as ; decreased optimum<br />
asphalt content, higher filler concentrations result in stronger pavement due to better asphalt<br />
cohesivity as well as internal stability from the good packing contributed by the filler, the inclusion <strong>of</strong><br />
mineral filler increases resilient modulus <strong>of</strong> asphalt mixtures, also excessive filler may weaken the<br />
mixture by extending the amount <strong>of</strong> asphalt or simply makes the asphalt stiff <strong>and</strong> consequently<br />
affecting the workability <strong>of</strong> the mixture, mineral fillers affect the engineering properties <strong>of</strong> the parent<br />
binder. Therefore, inappropriate amount <strong>of</strong> the mineral filler may lead to instability, rutting, moisture<br />
damage <strong>and</strong> cracking <strong>of</strong> the resulting asphalt mixture. Underst<strong>and</strong>ing <strong>of</strong> the effects <strong>of</strong> mineral filler<br />
additives to asphalt mixtures is very important prior to undertaking this task to avoid the<br />
aforementioned problems [7].<br />
Summary <strong>and</strong> Conclusions<br />
This study has presented a comprehensive methodology for the determination <strong>of</strong> mixing <strong>and</strong><br />
compaction temperatures shift curves for No. 70 asphalt mastic at different type <strong>and</strong> content <strong>of</strong><br />
mineral fillers. Test data presented in this study leads to several important conclusions as below.<br />
Due to stiffening <strong>and</strong> extension effect on original binders caused by mineral fillers, effect on<br />
viscosity is demonstrated. Fillers increase the viscosity at increased dust levels <strong>and</strong> hydraulic lime<br />
shows a more significant increment as compared to other fillers.<br />
<strong>Mixing</strong> <strong>and</strong> compaction temperature curves for No. 70 petroleum <strong>of</strong> China asphalt mastic at any<br />
different dust to binder ratio have been established using the figures generated in this study.<br />
Equi-viscous concept can be used to determine mixing <strong>and</strong> compaction temperatures for asphalt<br />
mixtures from asphalt mastics whose base binder is unmodified asphalt cement.<br />
The utility <strong>and</strong> significance <strong>of</strong> extensive tests evaluating the properties <strong>of</strong> asphalt binders in their<br />
original state are questionable without fillers. The measurement <strong>of</strong> paving mixture properties, rather<br />
than plain binders appears to be more rational.<br />
In paving mixtures, at temperatures <strong>of</strong> pavement use, the asphalt is admixed in thin films with a<br />
variety <strong>of</strong> mineral substances. With fillers, it forms binders varying greatly in properties <strong>of</strong> the<br />
original in-bulk asphalt. Additionally, the properties <strong>of</strong> the original asphalt are changed by heating in<br />
the hot paving mixture preparation process. Thus, utility <strong>and</strong> significance <strong>of</strong> extensive tests<br />
evaluating the properties <strong>of</strong> the binder at high temperatures, in its original state, are questionable. The<br />
measurement <strong>of</strong> paving mixture properties, rather than the properties <strong>of</strong> the binder, appears to be a<br />
more rational approach.<br />
A comparative effect <strong>of</strong> different type <strong>and</strong> content <strong>of</strong> mineral fillers on the laboratory<br />
determination <strong>of</strong> asphalt mixtures mixing <strong>and</strong> compaction temperatures has been achieved <strong>and</strong> master<br />
curves developed. The experimental results demonstrated that the presence <strong>of</strong> mineral fillers in<br />
asphalt mastic was able to give a positive shift change in the mixing <strong>and</strong> compaction temperatures<br />
compared to those determined from plain asphalt binders.<br />
Acknowledgement<br />
Special thanks to co-authors <strong>and</strong> the literature provided in support <strong>of</strong> this manuscript.<br />
165
International Journal <strong>of</strong> Civil Engineering <strong>and</strong> Building Materials (ISSN 2223-487X) Vol. 2 No.4 2012<br />
© 2012 International Science <strong>and</strong> Engineering Research Center<br />
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