| Definition |
A type of hydraulic cement in the form of finely
divided, gray powder composed of lime, alumina,
silica, and iron oxide as tetracalcium alumino-
ferrite (4Ca O?Al
2
O
3
?Fe
2
O
3
), tricalcium aluminate
(3Ca O?Al
2
O
3
), tricalcium silicate (3Ca O?Si O
2
),
and dicalcium silicate (2Ca O?Si O
2
). These are
abbreviated, respectively, as C
4
AF, C
3
A, C
3
S, and
C
2
S. Small amounts of magnesia, sodium, potas-
sium, and sulfur are also present. Hardening does
not require air and will occur under water. Cement
may be modified with various plastic latexes in pro-
portions up to 0.2 part latex solids to one part cement
to improve adhesion, strength, flexibility, and cur-
ing properties. Water evaporation can be retarded by
adding such resins as methylcellulose and hydrox-
yethylcellulose. For further information, refer to the
Portland Cement Association, 5420 Old Orchard
Road, Skokie, IL 60077-1083.
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