Figure 7-9.-Steel in place in a wall.
substituted for the metal supports only if there
concrete. This bond strength is proportional to
is no possibility of the concrete becoming wet or
the contact area surface of the steel to the
if the construction is known to be temporary.
concrete. In other words, the greater the surface
of steel exposed to the adherence of the concrete,
WALL REINFORCEMENT.— Placement of
the stronger the bond. A deformed reinforcing bar
steel reinforcement in load-bearing walls is the
same as for columns except that the steel is erected
in place and not preassembled. Horizontal steel
is tied to vertical steel at least three times in any
bar length. The wood block is removed when the
form has been filled up to the level of the block,
as shown in figure 7-9.
Reinforcing Steel
Steel is the best material for reinforcing
concrete because the coefficients of expansion of
the steel and the concrete are considered almost
the same; that is, at a normal temperature, they
will expand and contract at an almost equal rate.
(At very high temperatures, steel will expand more
rapidly than the concrete, and the two materials
will separate.)
Steel also works well as a reinforcement for
concrete because it makes a good bond with the
Figure 7- 10.-Types of deformed reinforcing bars.
7-6
