LOWER MOUNT INSTALLATION PROCEDURES
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2-32
SERIES 8116/8118 16-/18-METER EARTH STATION ANTENNA
42S183D
Grout is used between the concrete foundation surface and the six
base plates to ensure a rigid, load-bearing connection between the
mount and the foundation. Grout may also be placed between the
concrete foundation and the bottom bracket on the bottom skin
plates to ensure rigidity but is not required structurally. Standard
shipments include enough grout for the six base plates only. It is
important that the grout manufacturer's instructions be followed.
These instructions are packaged with the grout. For convenience,
the essentials of the procedure are repeated as follows:
The grout must completely fill all locations (see Figure 2-6).
Verify that each anchor bolt nut will have no less than two threads
above the nut. The normal ambient temperature range for good
"early-strength" grouting is 55°F to 80°F (13°C to 27°C). When
temperatures at the job site are outside this range, the procedures
given here must be modified to compensate for the high or low
temperature. If the temperature is outside the range, perform one
of the following procedures before proceeding to the grouting
procedure.
GROUTING
BASEPLATE AND
SKIN PLATE TO
FOUNDATION
Temperatures above 80°F (27°C) accelerate hardening of the grout,
reducing the time that the grout remains workable after mixing;
therefore, it is necessary that either procedures be used which
permit placing of the grout more quickly, or the available working
time increased by cooling the mixture and the mount base plates.
If the first approach is taken, it is suggested that grout be mixed for
each base plate separately and poured immediately. Mixing time
could be reduced to one minute by use of an electric drill and
mixing blade made of steel rod.
If the second approach is taken, grout working time may be
increased by use of cold materials, cool foundation, and base
plates. This approach involves the use of cold or iced water in the
mix to keep the as-mixed temperature of the grout under 70°F
(21°C), preferably between 50°F (10°C) and 55°F (13°C).
In either case, the following practices are recommended:
Hot Weather Grouting
1. Store bags of grout in as cool a place as practicable, but at least in the
shade. Avoid exposing the bags to dampness or rain.
2. Give extra attention to saturating the concrete foundation for 24 hours
before grouting. Heat and wind cause rapid evaporation; therefore, the
concrete should be wet liberally and frequently to prevent drying.
Consider the use of windbreaks and sunshades to maintain saturation.
3. Cool the base plates while saturating the foundation by covering the
plates with wet cloths and allowing evaporation to cool them.
