Aluminate cement is produced by
preparing raw meal consisting of applicable
bauxite and limestone,calcining the raw meal in
rotary kiln and grinding the clinker, which
contains Al2O3 50-59%. It
was called bauxite cement for a time and also
called "refractory cement" based on its main
usage. The name "aluminate cement" is specified
by the national standard
now.
The main minerals
in aluminate are monocalcium aluminate (CA),
monocalcium dialuminate (CA2), "12:7"
calcium aluminate (C12A7),
gehlenite (C2AS), minor perovskite
(CT) and dicalcium ferrite (C2F).
Among these minerals, CA hydrates rapidly and
sets normally with characters of rapid hardening
and early strengthening; CA2 hydrates
slowly and contributes to late strength. The
compressive strength at 3d for the cement
reaches about 90% of the maximum strength, thus
in the national standard, the compressive and
flexural strengths at 1d, 3d are specified to
determine cement grades.
The aluminate cement can resist a high
temperature at which a relative high strength
still remains. Its refractoriness increases with
the content of CA2. Therefore it is
suitable to make refractory concrete as a
binder. Depending on the refractory aggregates
(firecaly,high alumina) used, the refractory
concrete made of the cement can be used below
1400℃.
If it is used in
construction, attentions given in the appendix
GB201 must be followed. |