SOME CHARACTERISTICS OF HEAT-RESISTING CONCRETES
MODIFIED BY SiO
and R. Abraitis
Translated from Novye Ogneupory, No. 8, pp. 42 – 44, August, 2009.
Original article submitted April 27, 2009.
Nanoparticles of SiO
have been added in the preparation of heat-resisting concretes of two types. The
major technical and chemical characteristics have been determined. Features have been found in some of the
technological operations in making the concretes of both types, and also aspects of the physicomechanical
properties. Higher chemical stability has been found for heat-resisting concrete containing TiO
in an NaOH solution.
Keywords: nanoparticles, basic properties of heat-resisting concretes containing added nanoparticles, chemi
cal stability of heat-resisting concretes.
Wide use is made of heat-resisting concretes modified by
nanoparticles, but we know of no instance where
nanoparticles have been used in making heat-resisting
concretes. Titanium dioxide is beginning to be used in indus-
try, including in the form of finely ground powders; it has an
elevated dielectric constant, so it is used in many ceramic
materials belonging to the class of capacitor ceramics .
= 1825°C) leads to partial loss of oxygen
with the formation of blue Ti
. Also, TiO
insoluble in water. Further, TiO
is a mainly covalent com
pound (DE = 3.06 eV). The atomic structure of titanium di
oxide differs substantially from that of crystalline quartz
Figure 2 shows a representation of the structure of SiO
(crystal, formula (SiO
)n ) in planar form.
powder had a mean particle size of 150 nm,
while the titanium dioxide powder of purity 99.999% had a
particle size of 20 – 30 nm (calculated from the specific sur
face). The TiO
powder therefore disperses in air much more
than does the SiO
powder, and operations with the TiO
powder should be done with great care.
We prepared two types of heat-resisting concrete with
the addition of 5% (out of the total dry mass) of TiO
of RW Fuller grade, in order to compare the two
types. Bauxite components form the basis of the concrete, in
cluding fine-ground bauxite and two fractions of bauxite
grains 0 – 1 and 3 – 5 mm, which were introduced into the
concrete in identical amounts. We also used finely divided
of STS 20 grade. The mixture included the
Castament-20 deflocculent, which in all cases was used in
heat-resisting concrete containing nanoadditives. The bond-
ing agent was Gorkal-70 aluminate cement (8% of dry mass).
The dry mixture was treated with distilled water, the
amount of which was variable because of the differences in
grain-size composition. The surface area of the concrete con
powder was much greater than that with added
. The water used for the concrete containing TiO
der was 10% of the dry mass, as against 6% with the SiO
powder. These differences in water content meant that the
forced mixing in a mixer differed: with SiO
the required homogeneity was attained much more rapidly
than with TiO
, which was due not only to the different
amounts of water used but also to the chemical reactions be
tween the components. There was much later hardening of
the concrete containing TiO
. The specimens also behaved
differently in the molds: that containing TiO
did not stick to
the metal surface.
We prepared specimens as cubes with edges of 4 and
2 cm, which hardened in three days under normal conditions,
and then they were dried for two days at 100 – 110°C, after
which they were heated in an electric oven at 800, 1100, and
1300°C (Fig. 3). Those with edge size 4 cm were used in
measuring the density and speed of ultrasound, while those
with edge size 2 cm were used in determining the strength
(stress) and strain. The surfaces of specimens containing
Refractories and Industrial Ceramics Vol. 50, No. 4, 2009
1083-4877/09/5004-0295 © 2009 Springer Science+Business Media, Inc.
Thermal Insulation Institute, Gediminas High Technology Uni
versity, Kaunas, Lithuania.
Institute for Architecture and Construction, Kaunas Technologi
cal University, Lithuania.