Formwork for Concrete Structures by R.L.Peurifoy and G.D- By EasyEngineering.net

28 Chapter Three
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FIGURE 3-4 Distribution of Concrete Pressure for Example 3-3.
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Relationship between Rate of Fill, Temperature,
and Pressure for Wall Forms
Table 3-3 gives the relationship between the rate of filling wall forms,
lateral pressure, and temperature for placement heights up to 14 ft.
The pressures are based on 150 lb per cu ft density concrete with no
additives, a maximum slump of 7 in., and vibration to a depth of 4 ft
or less. For other concrete densities and blends, the pressures should
be adjusted by C w
and C c
. For rates of pour greater than 15 ft per hr,
the wall pressure should be calculated by P m
= wh.
In Table 3-3, the pressures for rates of replacement less than 7 ft
per hr are calculated by the equation P m
= C w
C c
[150 + 9,000R/T]. For
rates of placement from 7 to 15 ft per hr, the pressures are calculated
by P m
= C w
C c
[150 + 43,400/T + 2,800R/T]. However, these wall pressure
equations are limited to a maximum pressure of P m
= wh. For
example, if a wall form 14 ft deep is filled at a rate of 15 ft per hr at a
temperature of 40°F, Table 3-3 indicates a maximum pressure of 2,285
lb per sq ft. However, the maximum pressure is limited to P m
= wh =
(150 lb per cu ft) x (14 ft) = 2,100 lb per sq ft.
The wall pressure equations may be used to determine the maximum
pressures produced on wall forms, provided the forms are deep
enough to permit the calculated pressures to develop. For example, if
a wall form 6 ft deep is filled at a rate of 7 ft per hr at a temperature of
50°F, Table 3-3 indicates a maximum pressure of 1,410 lb per sq ft.
However, if the concrete weights 150 lb per cu ft, the maximum
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