HEAT-RESISTANT CORUNDUM CONCRETE
REINFORCED WITH ALUMINUM OXIDE FIBERS
SYNTHESIZED WITHIN A MATRIX DURING FIRING.
PART 5. BASES OF REINFORCED CORUNDUM CONCRETE
TECHNOLOGY AND STUDY OF PHYSICOMECHANICAL PROPERTIES
V. N. Sokov,
S. D. Sokova,
and V. V. Sokov
Translated from Novye Ogneupory, No. 1, pp. 32 – 33, January 2015.
Original article submitted September 23, 2014.
It is revealed that traditional methods for introducing discrete fibers used in a concrete composite are inade
quate. A special method is developed for uniform concrete mix reinforcement. It is shown that the main pro
cesses of reinforced concrete structure formation are dehydration of cement stone minerals and synthesis of
original fibers within corundum. Processes are complete at 1500 – 1600°C.
Keywords: corundum concrete thermal shock resistance, concrete reinforcement, fibers, vibration platform,
In order to prepare composite materials it expedient to
use short fibers, since random arrangement within a matrix
of relatively short fibers makes it possible to prepare material
with uniform strength throughout the volume. However, in
selecting fiber geometry it is necessary to bear in mind the
fact that the ratio of fiber length to diameter should not be
less than 20:1, since in fact this value, as established in , is
the optimum with object reinforcement. It should also be
noted that the length of fibers has a marked effect on the de
gree of their agglomeration: the shorter they are, the less is
the degree of agglomeration , and fiber distribution is
more uniform within a system.
During preparation of test reinforced corundum concrete
it was necessary to distribute a small weight of fibers (<2%)
throughout the whole volume. An effect of concrete rein
forcement will only be achieved in the case when it is possi
ble for an original amount of fiber to be separated to a maxi
mum into individual fibers and uniformly distributed within
a molded mix, making the material equally strong in all di
rections. However, uniform distribution of fibers used within
concrete is a very complex stage due to their tendency to
break into lumps, which in turn disrupts mix homogeneity.
We have checked various traditional versions of concrete
reinforcement , although their effect was not given. We
have established by experience that it is most expedient to in
troduce fibers into a mix through a vibration screen with cell
sizes of 3.0 – 5.0 mm. Vibration breaks segregated fiber
lumps within an original mix and facilitates uniform concrete
mix reinforcement. The duration of mix agitation and the se
quence of charging components affect quality.
A concrete composite was prepared in a blade mixer in
the following sequence. With continuous stirrer operation a
calculated amount of coarse and fine filler was added, and
mixed dry for 1.5 – 2.0 min, then cement was charged and
mixing continued for another 2.0 – 2.5 min. Then the rein
forcing component was added through a vibration screen into
the mixer, and after 2 min water was added and mixing con
tinued for another 3 min in order to prepare a uniform mold
ing mix with a moisture content of 25 – 28%. The precisely
dispensed mix was laid in a mold and spread with a scraper.
Specimen compaction was carried out on a low-frequency
vibration plate with a vibration frequency of 3000 rpm and
amplitude 0.2 – 0.3 mm. Rigid and sufficiently reliable fas
tening of a mold to a vibration plate is essential. The vibra
Refractories and Industrial Ceramics Vol. 56, No. 1, May, 2015
1083-4877/15/05601-0034 © 2015 Springer Science+Business Media New York
Parts 1 – 4 of the article published in Novye Ogneupory Nos.
5 – 8 (2014).
FGBOU VPO Moscow State Building University, Moscow, Russia.