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Applications > Perlite Concrete > Transit Mix Guidelines and
Procedures > Field Control
Field Control
The wet density can be checked for conformance to the
architect’s specifications beginning with the first truckload delivered. Adjustments
to the mixing procedure should be made at that time and additional checks made
periodically during pouring.
The simplest method of field checking wet density is as
follows:
- Determine the exact volume of a cylindrical container
such as a rigid 10-quart (10-liter) container. This can be done by first weighing the
empty container, then filling it completely full with water and weighing it again and
subtracting the two weights. This provides the net weight of the volume of water, and, if
divided by the density of the water, the result is the exact volume of the
container.
Example:
| Weight of Empty Container |
2.0 lbs. |
| Weight of Container Filled with Water |
23.0 lbs. |
| Net Weight of Water |
21.0 lbs. |
Volume= Net Weight of Water
÷ Density of Water = 21 ÷ 62.5 = 0.336 ft3
Example: (Using Metric Units)
| Weight of Empty Container |
.91 kg |
| Weight of Container Filled with Water |
10.45 kg |
| Net Weight of Water |
9.54 kg |
Volume = Net Weight of Water
÷ Density of Water = 9.54 kg ÷ 1000kg/m3
= 0.00954 m3
- Fill the container with wet perlite concrete as it leaves
the mixer and weigh again. Subtract the weight of the empty container and divide the
remainder by the volume as determined in Step 1. The result is the wet density of the
perlite concrete in pounds per cubic foot which should be within ± 2 lbs/ft3
(32 kg/m3) of the specified value.
Example: (Based on a 1:6 mix)
| Weight of Container Filled with Concrete |
15.5 lbs. |
| Weight of Empty Container |
2.0 lbs. |
| Weight of Perlite Concrete |
13.5 lbs. |
Wet Density = Weight of Perlite
Concrete ÷ Volume = 13.5÷ 0.336 = 40.2
lbs/ft3
The specified wet density of the 1:6 mix (94 lbs. of
Portland cement to 6 ft 3 of perlite aggregate) is 40.5 ± 2.0 lb/ft3.
Therefore, the field test wet density is within the specification range.
Example: (Based on a 1:6 mix) (Using metric units)
| Weight of Container Filled with Concrete |
7.05 kg |
| Weight of Empty Container |
.91 kg |
| Weight of Perlite Concrete |
6.14 kg |
Wet Density = Weight of Perlite
Concrete÷ Volume = 6.14÷ 0.00954 =
643.6 kg/m3
Therefore, the field test wet density is within the 648±
32 kg/m3 specification range.
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