Inhibition of the Alkaline Corrosion of Cement Materials
with Additions of Ultradispersed Silica
A. S. Brykov, A. S. Panfilov, and A. V. Anisimova
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received September 7, 2010
Abstract—Efficiency of ultradispersed and colloidal silica-containing materials as inhibitors of the alkaline
corrosion of cement formulations containing reactive fillers was studied. It was found that the dispersity of the
silica-containing materials affects their inhibiting capacity.
INORGANIC SYNTHESIS AND INDUSTRIAL
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 6, pp. 925–929. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.S. Brykov, A.S. Panfilov, A.V. Anisimova, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 6, pp. 902–906.
Silica-containing materials of technological origin,
used in high-quality construction concretes, such as
microsilica, carryover ash, and granulated blast-
furnace slags, more or less effectively hinder the
development of reactions between the alkaline medium
of the cement gel and fillers containing reactive
inclusions [amorphous, glassy, cryptocrystalline or
microcrystalline forms of SiO
(e.g., opal-like silica),
volcanic glass, chalcedony, flint] [1–3]. These reac-
tions, known in the domestic literature as alkali–silica
reactions (ASR), result in a gradual, or rather fast
disintegration of concrete and concrete structures if
these contain reactive fillers.
For suppression of ASR, it is important, in both
physical and chemical regards, that the specific surface
area (dispersity) of silica-containing additives should
be large. On the one hand, these additive result in that
the porosity decreases and a denser stone structure is
formed, which markedly restricts ingress of moisture
in the body of concrete and hinders propagation of the
product of ASR, alkali–silica hydrogel, in the concrete.
On the other hand, having a large specific surface area,
mineral additives substantially reduce the mobility of
alkaline cations and their concentration in the pore
fluid of the cement stone (concrete).
Despite the considerable advances in the prevention
of ASR, the problem of the alkaline corrosion of
concrete constructions remains topical because
numerous aspects of ASR mechanisms and the effect
of inhibitors remain unclear. Also open is the question
as to how long is the protective action of inhibiting
additives used in practice.
In practical regard, further search for effective
inhibitors among silica-containing materials may be
associated with ultradispersed silicas whose dispersity
is ten times greater than that of microsilica, the most
effective among highly dispersed silica-containing
additives presently used in concrete-related techno-
logies. Among the available technical products, atten-
tion should be given to silicas produced by hydro-
chemical synthesis, chemically precipitated and col-
loidal silicas with a specific surface area of SiO
particles of 100 to 500 m
and more . Compared
with microsilica, these materials exhibit a higher
pozzolanic activity, more intensely stimulate the
hydration of portland cement, and exert a pronounced
positive influence on physicomechanical properties of
mortars and concretes .
The goal of our study was to examine the efficiency
of ultradispersed and colloidal silica-containing
materials produced by hydrochemical synthesis (che-
mically precipitated and colloidal SiO
) as inhibitors of
the alkaline corrosion of portland cement concrete
formulations in comparison with microsilica.
In addition, we consider the effect of lithium
cations on the ability of highly dispersed silica to
inhibit the ASR. Lithium compounds are highly effect-
tive ASR inhibitors because, under conditions of
limited access of water, poorly soluble lithium silicates
are formed, which are not able to further absorb water