Determination of Mixing and Compaction Temperatures ... - ijcebm

Viscosity (Pa·s)
10.00
1.00
0.28
0.1
0.10
International Journal of Civil Engineering and Building Materials (ISSN 2223-487X) Vol. 2 No.4 2012
© 2012 International Science and Engineering Research Center
0.28±0.03 Viscosity lines
0.17±0.02 Viscosity lines
0.01
125 135 145 155 165 175 185 195 205
Temperature (°C)
Fig. 3 Viscosity versus temperature for limestone and No.70 petroleum
163
0 dust to binder ratio
Compaction range Mixing range
0.3 dust to binder ratio
0.6 dust to binder ratio
0.9 dust to binder ratio
1.2 dust to binder ratio
1.5 dust to binder ratio
Determination of asphalt mixtures compaction and mixing temperatures. Asphalt mixtures
mixing and compaction temperatures are determined at elevated temperatures from plain asphalt
viscosity – temperature charts at equiviscous lines 0.170±0.02 Pa·s and 0.280±0.03 Pa·s. The
measurement concepts can be extended to asphalt mastics because the viscosity is a well defined
function of temperature and mineral filler to binder ratio content within the cordinates defined in the
method stated in ASTM D 2493 for unmodified binders in the equi-viscous range [5]. A reasonable
determination of the asphalt mixtures mixing and compaction temperature master curve from asphalt
mastics viscosity data is important to avoid construction problems, due to heat damage of asphalt as
well as oxidation if mixed at excessive temperatures, and lead to the release of unacceptable levels of
“blue smoke” and cause difficulties in compaction. Using viscosity data generated for each type and
content of mineral filler, viscosity-temperature graphs are developed for each mineral filler and
mixing and compaction temperature values read off at each mineral filler content based on
0.170±0.02 Pa·s and 0.280±0.03 Pa·s. Equi-viscous lines. Fig. 4 shows the mixing and compaction
temperature master curves developed from viscosity data of the three mineral fillers. Depending on
the type and content of mineral filler recommended for use with No.70 (Penetration grade) bitumen,
the required asphalt mixtures mixing and compaction temperatures can be read off from the graph.
Asphalt cements within the same penetration grade would produce similar asphalt mixtures mixing
and compaction temperatures with the same binder type but a lower grade mixed with mineral fillers
determined using the equi-viscous concept. Viscosity - temperature measurements concept can also
provide useful data for temperature susceptibility of asphalt cements although different methods are
available to evaluate temperature susceptibility of asphalt cements, furthermore temperature indexes
vary and depend on the temperature range selected for the calculation of such indexes.
Temperature-Viscosity susceptibility is commonly used, because of its universality and fundamental
nature, and is preferred over the empirical methods utilizing either penetration measurements or
penetration and viscosity measurements at different temperatures. The interaction between filler
particles and the asphalt can be viewed in two ways: physical and chemical interaction. Physical
interaction between fillers and asphalt refers to formation of stiffened matrix. In chemical interaction,
certain fillers might be an active material and possibly react with the asphalt thereby altering the
property of the asphalt filler mastic [6,7].