Civil Engineering Reference
In-Depth Information
BLENDED HYDRAULIC CEMENTS
AASHTO M 240 also uses the above class designations
for blended cement. The requirements of M 240 are almost
identical to those in ASTM C 595.
ASTM C 1157
provides for six types of blended cement
as discussed under “Hydraulic Cements” below. Blended
cements meeting the requirements of
C 1157
meet physical
performance test requirements without prescriptive restric-
tions on ingredients or cement chemistry. This allows the
cement manufacturer to optimize strength and durability
properties through use of a variety of cementitious materi-
als, such as portland clinker, fly ash, slag, silica fume, and
calcined clay (Fig. 2-19).
A detailed review of ASTM C 595 and AASHTO M 240
blended cements follows:
Blended cements are used in all aspects of concrete
construction in the same manner as portland cements.
Blended cements can be used as the only cementitious
material in concrete or they can be used in combination
with other supplementary cementitious materials added at
the concrete plant. Blended cements are often designed to
be used in combination with local pozzolans and slags. If a
blended cement or portland cement is used alone or in
combination with added pozzolans or slags, the concrete
should be tested for strength, durability, and other proper-
ties required in project specifications (
PCA 1995
and
Detwiler, Bhatty, and Bhattacharja 1996
).
Blended hydraulic cements are produced by inti-
mately and uniformly intergrinding or blending two or
more types of fine materials. The primary materials are
portland cement, ground granulated blast-furnace slag, fly
ash, silica fume, calcined clay, other pozzolans, hydrated
lime, and preblended combinations of these materials (Fig.
2-19). Blended hydraulic cements must conform to the
requirements of ASTM C 595 (AASHTO M 240),
Specifi-
cation for Blended Hydraulic Cements,
or
ASTM C 1157
,
Per-
formance Specification for Hydraulic Cement
.
ASTM C 595 recognizes five primary classes of
blended cements as follows:
Type IS Portland blast-furnace slag cement
Type IP and Type P Portland-pozzolan cement
Type I(PM) Pozzolan-modified portland cement
Type S Slag cement
Type I(SM) Slag-modified portland cement
Types IS, IP, P, I(PM), and I(SM) are general purpose
cements (Fig. 2-12); these and subcategory types are re-
viewed in the discussion below.
Type IS
Portland blast-furnace slag cement, Type IS, may be used in
general concrete construction. Historical use of slag blended
cements dates back to the beginning of the 20th century in
Europe, Japan, and North America (
Abrams 1925
). In
producing these cements, granulated blast-furnace slag is
either interground with portland cement clinker, separately
ground and blended with portland cement, or produced
with a combination of intergrinding and blending. The
blast-furnace slag content of this cement is between 25%
and 70% by mass. Subcategory types (optional special prop-
erties) such as air-entrainment, moderate sulfate resistance,
or moderate heat of hydration may be specified by adding
the suffixes A, MS, or MH. For example, an air-entraining
portland blast-furnace slag cement that has moderate
sulfate resistance would be designated as Type IS-A(MS).
See
Klieger and Isberner (1967)
and
PCA (1995)
.
Type IP and Type P
Portland-pozzolan cements are designated as Type IP or
Type P. Type IP may be used for general construction and
Type P is used in construction not requiring high early
strengths. These cements are manufactured by intergrind-
ing portland cement clinker with a suitable pozzolan, by
blending portland cement or portland blast-furnace slag
cement and a pozzolan, or by a combination of intergrind-
ing and blending. The pozzolan content of these cements is
between 15% and 40% by mass. Laboratory tests indicate
that performance of concrete made with Type IP cement as
a group is similar to that of Type I cement concrete. Type IP
may be designated as air-entraining, moderate sulfate
resistant, or with moderate heat of hydration by adding the
suffixes A, MS, or MH. Type P may be designated as low
heat of hydration (LH), moderate sulfate resistant (MS), or
air entraining (A).
Fig. 2-19. Blended cements (ASTM C 595, AASHTO M 240, and
ASTM C 1157
) use a combination of portland cement or clinker
and gypsum blended or interground with pozzolans, slag, or
fly ash.
ASTM C 1157
allows the use and optimization of all
these materials, simultaneously if necessary, to make a
cement with optimal properties. Shown is blended cement
(center) surrounded by (right and clockwise) clinker, gypsum,
portland cement, fly ash, slag, silica fume, and calcined clay.
(68988)
Type I (PM)
Pozzolan-modified portland cement, Type I(PM), is used in
general concrete construction. The cement is manufactured
