PHYSICOMECHANICAL PROPERTIES OF MEDIUM-CEMENT
REFRACTORY CASTABLES CONTAINING CHAMOTTE-SILICON
CARBIDE FILLERS TESTED FOR PRACTICAL APPLICATIONS
and R. Stonis
Translated from Novye Ogneupory, No. 9, pp. 59 – 63, September, 2005.
Original article submitted April 18, 2005.
The physicomechanical properties of chamotte and silicon carbide fillers are compared and the compositions
for medium-cement refractory castables using mixtures of these fillers are formulated. Rheological features
and heat release kinetics of castables are studied and the effect of sintering temperatures on the properties of
castables is discussed. The newly designed castables were used to fabricate paving blocks for brick-burning
The medium-cement refractory castable containing
9 – 15% aluminate cement has currently been gaining
ever-increasing acceptance in the lining of industrial fur-
naces because of its advantages over the conventional and
low-cement castables . The medium-cement castable is
less expensive (because of the lesser demand on cement) and
shows a higher robustness to technological operations in the
preparation of castable paste (batching, mixing, or harden
ing) in comparison to low-cement castables. Medium-cement
castables are especially effective in fabricating structural ele
ments of tunnel kilns for burning building bricks with a ser
vice temperature of 900 – 1100°C (roof and floor blocks, lin
ing for kiln cars).
The proper choice of a filler with suitable technical and
economic characteristics is an important consideration for
formulating the composition of a refractory castable. More
often than not commercially available chamotte fillers fail to
meet the requirements placed on the castable operating under
specific service conditions, for example, with a frequent al
ternation of temperature. Silicon carbide fillers display much
better properties (Table 1); they can be prepared from broken
or discarded silicon carbide components. It stands to reason
that replacing part of the chamotte fillers with appropriate
silicon carbide fractions, one can develop castables with su
perior physicomechanical characteristics.
In , data were reported on the effect of a SiC additive
(10 – 30%) on the properties of a low-cement refractory
castable with aluminate fillers. The density and strength of
the castable thus prepared tended to decrease with increasing
SiC content. The reason for this behavior remains unclear;
perhaps, this might be due to the unfortunate grain composi-
tion of the filler.
Our goal in this study was to analyze the properties of
fillers prepared from chamotte and silicon carbide wastes, to
formulate the composition for a castable with improved
heat-resistance characteristics using the aforesaid fillers, to
examine the properties of the newly developed castable, and
to evaluate its potential use for the lining of thermal plants.
CHARACTERIZATION OF FILLERS
Medium-cement castables were developed using high-
aluminate cement (Gorkal-70), alumina cement (Gorkal-40),
and fillers based on broken chamotte and silicon carbide
components. Preliminarily, the fillers were tested for interac
tion with aluminate cements during the technological pro
cessing and subjected to high-temperature treatment.
Specimens (cubes with an edge of 5 cm) were cut out of
lumps of chamotte and silicon carbide and tested for density,
compressive strength, and ultrasonic pulse (USP) velocity.
Relevant mechanical and thermophysical characteristics
(based on our measurement and literature data ) are given
in Table 1.
Refractories and Industrial Ceramics Vol. 46, No. 5, 2005
1083-4877/05/4605-0333 © 2005 Springer Science+Business Media, Inc.
From materials submitted to the 3rd International Conference of
Refractory and Steel Makers, Moscow, April 14 – 15, 2005.
Gediminas Institute for Thermal Insulation, Vilnius, Lithuania.