LEARNING OBJECTIVE: Recognize the different characteristics associated with
concrete form design and concrete mix design; recognize the procedures in batching
concrete and estimate concrete construction and labor. Identify the procedures and
methods associated with precast and tilt-up construction.
Concrete construction, once confined largely to
paving and foundations, has been developed to the
point where both large and small buildings are now
constructed entirely of concrete with concrete joists
(usually called floor or grade beams), concrete studs
(usually called columns), concrete walls, concrete
floors, and concrete roofs.
This chapter explains some of the major factors
concerning the design of concrete forms by means of
specific examples. Information is also provided on
the various methods by which you can select the
proportions for quality concrete mixtures and adjust
these mixtures to suit job requirements. We also cover
types and uses of admixtures and slump testing
procedures. We point out some of the types of
equipment you are likely to encounter in concrete
construction. A brief discussion is also included on
precast construction and brick construction. But we
must first discuss safety practices and procedures that
should be considered the most important aspect of
concrete construction work.
In concrete construction, as in all types of
construction,a certain degree of danger is involved. To
help you do your concrete work safely, we will discuss
the various safety precautions concerning concrete.
Form construction and concrete placement have
peculiarities in each job; however, certain natural
conditions will prevail in all situations. Wet concrete
will always develop hydrostatic pressure and strain on
the forms. Therefore, all stakes, braces, and other
supporting members should be properly secured and
inspected before placing the concrete.
All formwork, shoring, and bracing should be
designed, fabricated, erected, supported, braced, and
maintained so that it will safely support all vertical and
lateral loads that might be applied until loads can be
supported by the structure.
All nailing should be correctly placed and secured
according to the plans and specifications. Careless
nailing and exposed nails in formwork are a major
cause of accidents.
Adequate scaffolding should be built to permit
crew members to stand clear of pouring areas.
Rebar caps are a MUST for all exposed vertical
Tools, particularly hammers, should be inspected
GFCIs must be used with all power tools, and
ensure the location of the GFCIs are close to your
Supervisor(s) should check all forms before each
pour. Stripped forms should be piled in advance of any
movement or change of direction. During night
operations, all equipment should be equipped with
sufficient flood spotlights to make the perimeter of the
operations clearly visible. The pouring bucket and the
boom of the paver operating controls should have a
synchronized warning device to function
automatically with the motion of either the boom or
the traveling bucket.
Personnel may be subject to cement poisoning
(lime); therefore, ensure they have their shirt sleeves
rolled down and wear gloves and goggles when
working with concrete.
If concrete buckets and cranes are used in pouring,
each bucket should be provided with a tag line or two,
depending on the location. A crew member should
never ride a free swinging concrete bucket during a