HEAT-RESISTANT CORUNDUM CONCRETE
REINFORCED WITH ALUMINUM OXIDE FIBERS SYNTHESIZED
WITHIN A MATRIX DURING FIRING.
PART 6. STUDY OF REINFORCED CORUNDUM CONCRETE
V. N. Sokov,
S. D. Sokova,
and V. V. Sokov
Translated from Novye Ogneupory, No. 2, pp. 39 – 40, February 2015.
Original article submitted September 23, 2014.
Special fibers introduced into concrete, transformed into corundum during firing and sintered with the matrix,
make it possible to redistribute stresses between matrix and fiber, to reduce shrinkage significantly within con
crete binder, and to improve object thermal shock resistance and supporting capacity.
Keywords: cyclic temperature action, stress relaxation, shrinkage phenomena, thermal shock resistance,
During the first heating of heat-resistant concrete there is
basic structure formation. Shrinkage phenomena in concrete
binder and thermal expansion of filler give rise to various
kinds of strains within a structure causing corresponding
stresses between components. Reactions occurring at high
temperature within solid phase between dispersed concrete
components increase these stresses in some cases, and relax
them in others. It is difficult to determine when these stresses
cause microcrack formation within a concrete structure, al
though in all cases they weaken the bond between structural
components and are the basis of heat-resistant concrete het
erogeneous structure separation into fragments, sometimes
commensurate with the component grain size.
Action of cyclic temperature on a concrete structure,
formed during the first heating and having weakened or bro
ken interlayers, facilitates microcrack formation and devel
opment in these interlayers, as a result of which a structure
may become fragmented.
The amount of refractory material structure fragmenta
tion for increasing heat resistance and substantiation of this
dependence has been considered in work by Strelov  and
other researchers. In studying fragmentation of heat-resistant
concretes it is necessary to bear in mind the fact that their
structure is formed from components with grain size from 0
to 20 mm, and strength properties of coarse grains and mor-
tar joining them may be similar or markedly different. In the
first case crack pass through mortar and grains, and fragment
size depends to a lesser extent on the size of the latter. In the
case of stronger grains of coarse filler cracks only pass
through mortar, and therefore filler grain size has a marked
effect on fragment size.
Introduction of a special fibers into concrete, converted
into corundum as a result of heat treatment and sintered with
the matrix, makes it possible to reduce shrinkage phenomena
in the binder to a considerable extent and increase refractory
concrete lining element supporting capacity and life due to
reinforcement, and also to withstand cyclic thermal action
due to stress redistribution between matrix and fiber. Mea
surement of linear dimensions is performed after specimen
heat treatment at 1600°C (Fig. 1).
The structure of refractory concrete is fundamentally dif
ferent from that of the most widespread refractories. First, re
fractory concrete is unfired material, and therefore on first
heating the structure undergoes physicochemical transforma
tions, markedly altering concrete physicomechanical and
thermophysical properties. A stabilized concrete structure is
Refractories and Industrial Ceramics Vol. 56, No. 1, May, 2015
1083-4877/15/05601-0083 © 2015 Springer Science+Business Media New York
Parts 1 – 4 of the article published in Novye Ogneupory Nos.
5 – 8 (2014), part 5 in No. 1 (2015).
FGBOU VPO Moscow State Building University, Moscow, Rus