QUALITY AND CERTIFICATION
METHODS FOR DETERMINING HYDRATION RESISTANCE
I. Yu. Khlebnikova,
A. E. Zhukovskaya,
and A. N. Selivanova
Translated from Novye Ogneupory, No. 4, pp. 62 – 66, April, 2007.
Original article submitted November 1, 2006.
The “SPb SEC” Association has developed a standard of the organization (STO) “Refractories. Method for
Determining Hydration Resistance.” The standard covers powders and articles based on magnesium oxide.
The hydration resistance of powders is evaluated in terms of the change in the mass or in the grain composi
tion of a sample after treating it with steam under pressure; the hydration resistance of articles is estimated
from the change in their appearance.
Refractories based on periclase (magnesium oxide) and
bearing calcium oxide can undergo hydration in a warm hu-
mid atmosphere. In this case the powder grains break, the
material is pulverized, and the articles crack. Various meth-
ods exist for determining the hydration resistance of refracto-
ries. The most frequently used methods are (1) treatment of
the tested material with steam at normal or elevated pressure
and a temperature corresponding to the steam pressure and
(2) holding in a climatic chamber at a temperature below
100°C at a high moisture content. The second method is
closer to natural conditions under which such articles are
stored, especially in a humid tropical climate, but the test
takes a long time. In Great Britain and in the USA the meth
ods for determining the hydration resistance of refractories
have been standardized. The main items of the standards are
presented in Table 1.
In Russia, where periclase and periclase-containing
refractories are produced in considerable volumes, such stan
dards are absent. In this connection it seems appropriate to
evaluate the hydration resistance of domestic and imported
refractories used in the RF. It has been decided that a method
for determining hydration resistance should be developed
The “St. Petersburg Scientific-and-Engineering Center”
Association of Producers and Consumers of Refractories
(“SPb SEC” Association) has developed a standard of the or
ganization (STO) “Refractories. Method for Determining
Hydration Resistance.” The STO has been created with al
lowance for the experience of foreign standardization and for
the results of an experimental study. The method consists in
treating the studied samples and refractory specimens with
steam under specified conditions and subsequent evaluation
or visual estimation of the changes that have occurred.
The choice of the method for preparing samples of gran-
ular materials (powders) was preceded by an analysis of
standards for periclase powders (GOST 24862, GOST
10369, etc.) [1, 2]. It was established that the majority of
such powders consist of fractions finer than 4 mm. Accord-
ingly, a representative sample for the test is prepared by mill-
ing the powder for passage through sieve No. 4 and screen
ing the undersize through screen No. 0.1. It should be noted
that producers in Great Britain and in the USA use periclase
powders with coarser grain composition and thus test sam
ples with larger grains (see Table 1).
The material can be partially hydrated during storage,
milling, and screening. In order to ensure the same initial
state the samples are baked at 1000°C to a constant mass.
With allowance for the experience of Britain specialists
in determination of hydration resistance we made tests on
treating refractories with steam in a household pressure
cooker, the steam temperature in which was 105 – 108°C.
We poured 50 g of the tested material into a porcelain bowl
dried to a constant mass and placed the bowl into the pres
sure cooker on a special rest. Three parallel samples were
tested at a time. The steam treatment lasted for 1, 2, and 5 h.
Then we determined the changes in the mass and in the grain
composition of the sample. For this purpose the bowls with
the samples were dried to a constant mass, weighed, and
used to calculate the change in the mass of the sample; the
dried sample was screened through screen No. 01. The re
mainder on the screen (or on the underpan) was weighed and
Refractories and Industrial Ceramics Vol. 48, No. 2, 2007
1083-4877/07/4802-000142 © 2007 Springer Science+Business Media, Inc.
“St. Petersburg Scientific-and-Engineering Center” Association,
St. Petersburg, Russia.