Civil Engineering Reference
In-Depth Information
MPa
ksi
MPa
ksi
6
6
40
40
5
5
28-day
30
30
4
4
28-day
7-day
3
3
20
20
7-day
3-day
2
2
3-day
10
10
1
1
1-day
1-day
0
0.4
Water-cementitions materials ratio
0
0
0
0.5
0.6
0.4
Water-cementitions materials ratio
0.5
0.6
0.7
(a)
(b)
FIGURE 6.7
Typical age-strength relationships of concrete based on compres-
sion tests of 0.15 x 0.30 m (6 x 12 in.) cylinders, using Type I portland cement and
moist-curing at 21C (70F): (a) air entrained concrete, (b) non-air entrained concrete
(Kosmatka et al. 1988).
6.9
Types of Portland Cement
Different concrete applications require cements with different properties.
Some applications require rapid strength gain to expedite the construction
process. Other applications require a low heat of hydration to control vol-
ume change and associated shrinkage cracking. In some cases, the concrete
is exposed to sulfates which can deteriorate normal portland cement
concrete. Fortunately, these situations can be accommodated by varying the
raw materials used to produce the cement, thereby altering the ratios of the
four main compounds of portland cement listed in Table 6.1. The rate of hy-
dration can also be altered by varying the fineness of the cement produced
in the final grinding mill. Cement is classified to five standard types, as well
as other special types.
1
SO
4
2
,
■
6.9.1
Standard Portland Cement Types
Table 6.3 describes the five standard types of portland cement (Types I
through V) specified by ASTM C150. In addition to these five types, air en-
trainers can be added to Type I, II, and III cements during manufacturing,
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