Civil Engineering Reference
In-Depth Information
by combining portland cement or portland blast-furnace
slag cement and a fine pozzolan. This may be accom-
plished by either (1) blending portland cement with a
pozzolan, (2) blending portland blast-furnace slag cement
with a pozzolan, (3) intergrinding portland cement clinker
and a pozzolan, or (4) a combination of intergrinding and
blending. The pozzolan content is less than 15% by mass of
the finished cement. Air-entrainment, moderate sulfate
resistance, or moderate heat of hydration may be desig-
nated in any combination by adding the suffixes A, MS, or
MH. An example of an air-entraining, moderate-heat-of-
hydration Type I(PM) cement would be designated as Type
I (PM)-A(MH).
chemistry as found in other cement specifications. ASTM C
1157 provides for six types of hydraulic cement as follows:
Type GU General use
Type HE High early strength
Type MS Moderate sulfate resistance
Type HS High sulfate resistance
Type MH Moderate heat of hydration
Type LH Low heat of hydration
In addition, these cements can also have an Option R—
Low Reactivity with Alkali-Reactive Aggregates—speci-
fied to help control alkali-silica reactivity. For example,
Type GU-R would be a general use hydraulic cement with
low reactivity with alkali-reactive aggregates.
When specifying a C 1157 cement, the specifier uses
the nomenclature of “hydraulic cement,” “portland
cement,” “air-entraining portland cement,” “modified
portland cement” or “blended hydraulic cement” along
with a type designation. For example, a specification may
call for a Hydraulic Cement Type GU, a Blended Hydraulic
Cement Type MS, or a Portland Cement Type HS. If a type
is not specified, then Type GU is assumed.
ASTM C 1157 defines a blended cement as having more
than 15% mineral additive and a modified portland cement
as containing up to 15% mineral additive. The mineral addi-
tive usually prefixes the modified portland cement nomen-
clature, for example, slag-modified portland cement.
ASTM C 1157 also allows a strength range to be speci-
fied from a table in the standard. If a strength range is not
specified, only the minimum strengths apply. Strength
ranges are rarely applied in the United States.
A detailed review of ASTM C 1157 cements follows:
Type S
Slag cement, Type S, is used with portland cement in
making concrete or with lime in making mortar, but is not
used alone in structural concrete. Slag cement is manufac-
tured by either (1) blending ground granulated blast-
furnace slag and portland cement, (2) blending ground
granulated blast-furnace slag and hydrated lime, or (3)
blending a combination of ground granulated blast-
furnace slag, portland cement, and hydrated lime. The
minimum slag content is 70% by mass of the slag cement.
Air-entrainment may be designated in a slag cement by
adding the suffix A, for example, Type S-A.
Type I (SM)
Slag-modified portland cement, Type I(SM), is used for
general concrete construction. This cement is manufac-
tured by either (1) intergrinding portland cement clinker
and granulated blast-furnace slag, (2) blending portland
cement and finely ground granulated blast-furnace slag, or
(3) a combination of intergrinding and blending. Slag is less
than 25% by mass of the finished cement. Type I(SM) may
be designated with air-entrainment, moderate sulfate
resistance, or moderate heat of hydration by adding the
suffixes A, MS, or MH. An example would be Type I(SM)-
A(MH) for an air-entraining, slag-modified portland ce-
ment with moderate heat of hydration.
Type GU
Type GU is a general-purpose cement suitable for all uses
where the special properties of other types are not required.
Its uses in concrete include pavements, floors, reinforced
concrete buildings, bridges, pipe, precast concrete products,
and other applications where Type I is used (Fig. 2-12).
HYDRAULIC CEMENTS
Hydraulic cements set and harden by reacting chemically
with water. They also stay hard and maintain their stability
under water. They are used in all aspects of concrete con-
struction. All portland and blended cements are hydraulic
cements. “Hydraulic cement” is merely a broader term. See
also ASTM C 219 for terms relating to hydraulic cements.
The 1990s saw the creation of a performance specifica-
tion for hydraulic cements—ASTM C 1157,
Performance
Specification for Hydraulic Cements.
This specification is de-
signed generically for hydraulic cement to include port-
land cement, modified portland cement, and blended
hydraulic cement. Cements meeting the requirements of C
1157 meet physical performance test requirements, as op-
posed to prescriptive restrictions on ingredients or cement
Type HE
Type HE cement provides higher strengths at an early age,
usually a week or less. It is used in the same manner as Type
III portland cement (Fig. 2-17).
Type MS
Type MS cement is used where precaution against moderate
sulfate attack is important, as in drainage structures where sul-
fate concentrations in ground waters are higher than normal
but not unusually severe (see Table 2-2). It is used in the same
manner as Type II portland cement (Fig. 2-14). Like Type II,
Type MS cement concrete must be made with a low water-
cementitious materials ratio to provide sulfate resistance.
