TRANSIT MIXER SAFETY
Figure 3-16.Mobile concrete mixer plant.
The use of transit mixers on construction projects
impose traffic problems that must be considered.
Caution must be used during backing of the transit
mixer. Backing should be controlled by a signalman,
positioned so the operator can clearly observe the
directions given. Extreme caution must be used when
traveling over uneven terrain on a construction site.
The stability of the mixer is greatly reduced with the
extra weight of the concrete in the mixer unit. In such
cases, a slow speed is recommended.
Some additional safety precautions that must be
enforced are as follows:
1. Secure the discharge chute properly, using the
2. Check to make certain other personnel are in the
clear before starting the mixer charging or discharging.
3. Make sure the mixer is stopped before making
PRECAST AND TILT-UP
Precast and tilt-up construction is the fabrication
of structural members or panels at a place other than
its final position of use. It can be done anywhere,
although these procedures are best adapted to a factory
or prefab yard. Jobsite precasting is not uncommon for
large projects. Precast concrete can be produced in
several different shapes and sizes, including piles,
girders, and roof members. Prestressed concrete is
especially well-adapted to precasting techniques.
Tilt-up concrete is a special type of precast
concrete in which the units are tilted up and placed,
using cranes or other types of lifiing devices.
Wall construction, for example, is frequently done
with precast wall panels originally cast horizontally
(sometimes one above the other) as slabs. This method
has many advantages over the conventional method of
casting in place in vertical wall forms. Since a slab
form requires only edge forms and a single surface
form, the amount of formwork and form materials