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> Blended Cements Blended
Cements Get New Type Designations
 Blended
cements are portland-based cements that include supplementary cementitious
materials (SCMs), such as ground granulated blast-furnace slag,
fly ash or other pozzolans, such as silica fume or metakaolin.
ASTM C 595-06, Standard Specification for Blended Cements,
was released in August 2006 with some important changes to nomenclature.
The specification was simplified with the intent of making it easier
to use and to eliminate a problem with producing cements near the
boundaries. For example, the old Type IP cement used to contain
between 15% and 40% pozzolan, while a Type I(PM) cement contained
between 0% and 15% pozzolan. These definitions made it nearly impossible
for a manufacturer to produce a blended cement with around 15% fly
ash, as with normal process variation, it would sometimes be classified
as a Type IP and sometimes a Type I(PM). Both types were eliminated
and replaced by Type IP(X), where the letter “X” stands
for the nominal percentage of the SCM included in the blended cement.
For example a cement designated as Type IP(20) contains 20% by mass
of pozzolan. This will facilitate communication of the amounts of
SCM in concrete mixtures, which may also contain other added SCMs,
and may be subject to restrictions on the total amount of SCMs in
the concrete.
Summary of changes:
- Type I(PM), I(SM), I(PM)-A, I(SM)-A, and S were eliminated
- New portland-pozzolan cement,Type IP(X,) can include between
0% and 40% pozzolans, replacing old Types IP and I(PM)
- New portland blast-furnace slag cement, Type IS(X), can include
between 0% and 95% ground granulated blast-furnace slag, replacing
the old Types IS, I(SM), and S
- The letter “X” stands for the nominal percentage
of the SCM included in the blended cement
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