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

422 Chapter Fifteen
Downloaded From : www.EasyEngineering.net
taken out of operation, if this is desired, to bring sections of the
forms to uniform elevations. One person can operate the electric
motor that drives the pump, or the motor can be operated automatically
to any set cycle.
Operation of Slipforms
After a set of slipforms is completely assembled on a concrete base, the
forms are filled slowly with concrete. When the concrete in the bottom
of the forms has gained sufficient rigidity, the upward movement of
the forms is started and continued at a speed that is controlled by the
rate at which the concrete sets. Lifting rates may vary from 2 or 3 in.
per hr to in excess of 12 in. per hr, depending on the temperature and
other properties of the concrete. An experienced person should be
present at all time to establish the rate of movement. The reinforcing
steel is placed as the forms move upward.
ww.EasyEngineering.n
Constructing a Sandwich Wall
Where a wall is desired that has better insulating properties than
solid concrete, it is possible to place insulating material between the
inner and outer sections of the wall. This method is illustrated in
Figure 15-6. As the forms move upward, boards of insulating materials
are set into the guides above the concrete to provide a continuous
insulating medium. Metal ties should be installed between the
two sections of the wall at frequent intervals to hold the insulation
boards together.
FIGURE 15-6
Method of
constructing a
sandwich wall
using slipforms.
Downloaded From : www.EasyEngineering.net