EXAMPLE:
Determine the plan area for a concrete wall form that is 15 feet long x 2 feet wide x 6 feet
high.
Plan area = 15 x 2 = 30 sq ft
(4)
Problem 7. Work the following problem to see how well you understand the concept
covered in step 3. The solution to this problem is found at the end of the lesson. Determine
the plan area for a form that is 33 feet long x 3 feet wide x 7 1/2 feet high.
A.
30
B.
33
C.
66
D.
99
Step 4. Determine the rate of placing. Having determined the mixer output (step 2) and the
plan area (step 3), it is now time to compute the rate of placing. Determine the rate of placing
of concrete in the form by dividing the mixer output by the plan area. The rate of placing is
measured in vertical FPH. Compute as follows:
mixer output (cu FPH)
R (FPH) =
(5)
plan area (sq ft)
where--
R = rate of placing
If the answer contains a decimal, round to one decimal place. For example, for 1.41,
use 1.4; for 1.57, use 1.6.
The rate of placing should be kept 5 FPH for the most economical design.
EXAMPLE:
Determine the rate of placing if the mixer output is 7 cubic yards per hour (7 x 27 = 189
cubic FPH) and the plan area is 15 x 2 feet.
189
189
R=
=
= 6.3, use 5 FPH
(6)
15 x 2
30
Problem 8. Work the following problem to see how well you understand the concept
covered in step 4. The solution to this problem is found at the end of the lesson. Determine
the rate of placing if the mixer output is 7 cubic yard per hour (189 cubic FPH) and the plan
area is 33 x 3 feet.
A.
0.8
B.
1.9
C.
2.3
D.
3.1
Step 5. Determine the concrete placing temperature. Determine the concrete placing
temperature by making a reasonable estimate of the placing temperature of the concrete.
During the various seasons of the year, you will have to consider the ambient
(environmental) temperature. The optimum concrete temperatures are 55 to 73F. If the
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