LEARNING OBJECTIVE: Upon completing
this section, you should be able to describe
the proper placing procedures for
You cannot obtain the full value of well-designed
concrete without using proper placing procedures.
Good concrete placing and compacting techniques
produce a tight bond between the paste and aggregate
and fill the forms completely. Both of these factors
contribute to the full strength and best appearance of
concrete. The following are some of the principles of
Segregation Avoid segregation during all
operations, from the mixer to the point of
placement, including final consolidation and
Consolidation Thoroughly consolidate the
concrete, working solidly around all embedded
reinforcement and filling all form angles and
Bonding When placing fresh concrete
against or upon hardened concrete, make sure
that a good bond develops.
Temperature control Take appropriate steps
to control the temperature of fresh concrete
from mixing through final placement. Protect
the concrete from temperature extremes after
Maximum drop To save time and effort, you
may be tempted to simply drop the concrete
directly from the delivery chute regardless of
form height. However, unless the free fall into
the form is less than 4 feet, use vertical pipes,
suitable drop chutes, or baffles. Figure 7-41
suggests several ways to control concrete fall.
Good control prevents honeycombing and
other undesirable results.
Figure 7-41.-Concrete placing techniques.