Civil Engineering Reference
In-Depth Information
Table 2-2. Types of Cement Required for Concrete Exposed to Sulfates in Soil or Water
Minimum design
Water-soluble
Maximum water-
compressive
Sulfate
sulfate (SO
4
) in soil,
Sulfate (SO
4
)
cementitious material
strength,
f
c
, MPa (psi)
exposure
percent by mass
in water, ppm
Cement type**
ratio, by mass
Negligible
Less than 0.10
Less than 150
No special type required
—
—
II, MS, IP(MS), IS(MS), P(MS),
Moderate*
0.10 to 0.20
150 to 1500
0.50
28 (4000)
I(PM)(MS), I(SM)(MS)
Severe
0.20 to 2.00
1500 to10,000
V, HS
0.45
31 (4500)
Very severe
Over 2.00
Over 10,000
V, HS
0.40
35 (5000)
* Seawater.
** Pozzolans or slags that have been determined by test or service record to improve sulfate resistance may also be used.
Test method:
Method for Determining the Quantity of Soluble Sulfate in Solid (Soil or Rock) and Water Samples,
Bureau of Reclamation, 1977.
Source: Adapted from
Bureau of Reclamation 1981
and ACI 318.
1
concrete. The reaction products of sulfate attack are also
more soluble in a chloride solution and can leach out of the
concrete. Observations from a number of sources show
that the performance of concretes in seawater with port-
land cements having C
3
A contents as high as 10%, have
shown satisfactory durability, providing the permeability
of the concrete is low and the reinforcing steel has
adequate cover.
Type II cements specially manufactured to meet the
moderate heat
option
of ASTM C 150 (AASHTO M 85) will
generate heat at a slower rate than Type I or most Type II
cements. The requirement of moderate heat of hydration
can be specified at the option of the purchaser. A cement in
which heat-of-hydration maximums are specified can be
used in structures of considerable mass, such as large piers,
large foundations, and thick retaining walls (Fig. 2-16). Its
use will reduce temperature rise and temperature related
cracking, which is especially important when concrete is
placed in warm weather.
Because of its increased availability, Type II cement is
sometimes used in all aspects of construction, regardless of
the need for sulfate resistance or moderate heat genera-
tion. Some cements may be labeled with more than one
type designation, for example Type I/II. This simply
means that such a cement meets the requirements of both
cement Types I and II.
2
ASTM Type V
w/c = 0.37
ASTM Type II
w/c = 0.38
ASTM Type I
w/c = 0.39
3
4
Cement content = 390 kg/m
3
(658 lbs/yd
3
)
5
0
2
4
6
8
10
12
14
16
Age, years
1
w/c = 0.38
w/c = 0.47
w/c = 0.68
2
3
4
Type III
5
0
2
4
6
8
10
12
14
16
Type III portland cement provides strength at an early
period, usually a week or less. It is chemically and physi-
cally similar to Type I cement, except that its particles have
been ground finer. It is used when forms need to be
removed as soon as possible or when the structure must be
put into service quickly. In cold weather its use permits a
reduction in the length of the curing period (Fig. 2-17).
Although higher-cement content mixes of Type I cement
can be used to gain high early strength, Type III may
provide it easier and more economically.
Age, years
Fig. 2-13. (top) Performance of concretes made with different
cements in sulfate soil. Type II and Type V cements have lower
C
3
A contents that improve sulfate resistance. (bottom) Im-
proved sulfate resistance results from low water to cemen-
titious materials ratios as demonstrated over time for concrete
beams exposed to sulfate soils in a wetting and drying envi-
ronment. Shown are average values for concretes containing a
wide range of cementitious materials, including cement Types
I, II, V, blended cements, pozzolans, and slags. See Fig. 2-15 for
rating illustration and a description of the concrete beams
(
Stark 2002
).
