ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 11, pp. 1804 !1808. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + N.Kh. Belous, V.D. Koshevar, T.E. Kreer, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 11, pp. 1779!1783.
AND INDUSTRIAL INORGANIC CHEMISTRY
Complex Plasticizing Additives for Cement Mortars
N. Kh. Belous, V. D. Koshevar, and T. E. Kreer
Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
Received March 29, 2007
Abstract-New complex plasticizing additives for mortars based on Portland cement, increasing the mobility
of the cement paste and improving some technological properties of the resulting materials, were prepared.
Wide use of various chemical modifying agents of
various functional purpose is a typical feature of
modern building technology. For example, corre-
sponding plasticizers are widely used to provide
the required properties of concretes and building
mortars for the monolithic, composite, and composite-
monolithic building constructions. These additives
control the rheological properties of the cement paste,
improve its mobility and placeability, and provide
retention of its consistence, which, in turn, decreases
the water consumption of mortars and enhances the
strength parameters of the resulting objects .
Plasticizing additives optimize the setting time of
the cement paste, providing transportation of the
quality cement paste to the destination point and
shorter time in which the formwork of concrete struc-
tures can be stripped .
Both domestic plasticizers of naphthalenesulfonic
type (S-3, Russia), which have certain disadvantages,
and new imported plasticizers (as a rule, polycarboxy-
silicate superplasticizers, such as Stachement-2000,
Sika Visco Crete, Socolan ) are widely used in
the monolithic building. Such additives decrease the
water content by 353 40% and strongly increase the
concrete strength . Therefore, search for new types
of domestic plasticizers and their adaptation to the
cements produced in Belarus are urgent problems.
This study concerns preparation of new complex
plasticizers, their addition to mortars based on the
Portland cement, and properties of materials and
mortars based on them.
The complex plasticizers were prepared by mixing
of an unsaturated fatty acid or its sodium salt with
a modified tertiary amine in a wide range of the
weight ratios. The process was carried out in a high-
speed stirrer or ultrasonic dispersant (UZDN-1U,
15 kHz) providing high dispersity, uniformity, and
stability of the resulting emulsions.
The complex additives (CAs) contain a hydrophilic
microfoaming water-soluble component, namely,
modified tertiary amine (MTA) and other components
whose hydrophilic3lipophilic balance was varied in
a wide range (from 1 to 18): unsaturated fatty acid
(CA-1), a salt of fatty acid (CA-2), and the reaction
product of the acid and alkanolamine (CA-3). We
tested various procedures for preparing complex addi-
tives: addition of hydrophobic component (unsaturated
fatty acid) into an organic solvent with subsequent
mixing with a water-soluble component, mixing of
acid with modified tertiary amine in the presence of
emulsifier (CA-1), and mixing of the reaction product
of the acid and alkanolamine with MTA (CA-3).
The above procedures provide after mixing the forma-
tion of CAs exhibiting superadditive plasticizing ef-
fect, because, as was found, none of the individual
components used in these systems provides effective
thinning effect even at its high content in the mortar.
The complex plasticizers were added into the mor-
tars in amounts from 0.5 to 0.8 wt %. The experi-
ments were carried out using cement3sand blends
based on domestic additive-free cement [M500 DO
brand, GOST (State Standard) 10 178385, Belarus
Cement Plant, Kostyukovichi, Belarus]. This cement
is characterized by elevated content of aluminate com-
ponent with high specific surface area. Before prepara-
tion of the cement3sand blends (cement : sand =
1 : 1.5), the sand was dried to constant weight and
sieved; 0.1632.00-mm fractions were used. The addi-
tives were introduced either directly at tempering of