1070-4272/03/7603-0491$25.00C2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 3, 2003, pp. 491! 496. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 3,
2003, pp. 506!511.
Original Russian Text Copyright + 2003 by Syroezhko, Begak, Fedorov, Gusarova.
OF FOSSIL FUEL
Modification of Paving Asphalts with Sulfur
A. M. Syroezhko, O. Yu. Begak, V. V. Fedorov, and E. N. Gusarova
St. Petersburg State Technological Institute, St. Petersburg, Russia
Mendeleev Russian Research Institute of Metrology, State Unitary Enterprise, St. Petersburg, Russia
Kirishinefteorgsintez Production Association, Limited Liability Company, Kirishi, Leningrad oblast, Russia
Received October 31, 2002
Abstract-Sulfur dissolved in oil components of asphalt is a binder, filler, and chemical co-reagent at once.
The structure of sulfur-extended asphalt depends on its formula and heating temperature. Road pavement
based on sulfur-extended asphalt demonstrates higher durability as compared to that with the conventional
Road pavement based on sulfur-extended asphalt
demonstrates better mechanical characteristics and
durability as compared to that based on the conven-
tional binders. Recently there has been a steadily
growing interest in sulfur-extended asphalts, because
of the need in more rational utilization of great
amounts of sulfur compounds from petroleum refining
Sulfur is readily soluble in bitumen, especially in
its aromatic components. The solubility of elementary
sulfur in oxidized paving asphalts
at least 20 wt % .
Addition of sulfur in amount of up to 20 wt %
to asphalt initiates chemical reactions whose type
depends on the sulfur content and heating temperature
and time of a given mixture. For example, some com-
peting reactions can occur, including those with
sulfur incorporation into the bitumen molecules or
dehydrogenation with liberation of hydrogen sulfide.
At heating temperature T < 140oC, elementary sulfur
forms polysulfides in which unreacted sulfur dis-
solves. Along with asphaltenes, the indicated sulfur-
containing compounds play a role of a structure-form-
ing agent, i.e., they initiate formation of a network
in which asphaltenes, paraffin, and sulfur stand as a
dispersed phase, and molecules of resins and oils
(malthenes), as a dispersion medium. Such structures
differ considerably in the chemical and thermal stabil-
ity from similar structures in unmodified oil asphalts.
Above 140oC, dehydrogenation of saturated com-
ponents of bitumens can occur, whose depth depends
on the final temperature of the reaction mixture. Also
Paving asphalts from West-Siberian crude oil.
linear polysulfides can transform into stable cyclic
thiophene structures. With increasing temperature,
highly reactive asphaltenes and tars and also naphth-
ene3aromatic compounds can react with sulfur through
formation of the C3S bond.
It is known  that, at about 240oC, the reaction
of sulfur with naphthene-aromatic compounds of
bitumens gives asphaltenes, which play the crucial
role in formation of a complex structural colloidal unit
Therefore, sulfur, as a chemical coreagent and filler,
can have a considerable effect on the performance
characteristics of paving asphalts. This effect was
studied in this work.
In experiments we used elementary sulfur, BND
60/90 paving asphalt and tar from the KINEF Limited
Liability Company, broken granite (fraction 335 mm)
from the Pulkovo asphaltic concrete plant, and gab-
brodiorite (fraction 335 mm) from the Kuznechnoe
deposit (Leningrad oblast).
The initial BND 60/90 paving asphalt has a soften-
ing point (T
)of49oC and penetration (P
Sulfur-extended composites were prepared as fol-
lows. A weighed portion of BND 60/90 was heated in
a metallic crucible to 120oC, and then a fixed amount
of elementary sulfur was added with vigorous stirring
of the reaction mixture for 30 min.
The ring and ball softening point was determined
according to GOST (State Standard) 9950; penetra-