Page 55 - Masonry and Concrete

Concrete Construction Techniques
54 CHAPTER THREE

the diameter of the bar, or a minimum of
Column 12 in. and tie them securely together with
Height, Largest Dimension of Column, L, in inches
feet 16 18 20 24 wire (Figure 3-19). For example, if the bar
1
1
is 2-in. diameter (No. 4 bar), 30 2 in.
1 31 29 27 23
15-in. lap. Intersecting steel reinforcing
2 31 29 27 23
3 31 28 26 23 bars should also be tied to hold them
4 31 28 26 23 together when the concrete is poured. The
5 31 28 26 23
wire used to tie reinforcing should be a
6 30 28 26 23
soft annealed wire, usually 16- or 14-gauge
7 30 28 24 22
8 30 26 24 16 thickness.
9 29 26 19 16 For some applications, reinforcing bars
10 29 20 19 14
will have to be bent to certain shapes. Fig-
11 21 20 16 13
12 21 18 15 12 ure 3-20 shows some typical bar shapes
13 20 16 15 11 and end hooks, as well as minimum diam-
14 18 16 14 10
eter of bend for various bar diameters.
15 18 15 12 9
Reinforcing bars can be cut to size and
16 15 13 11 9
bent on site or ordered from a steel fabrica-
FIGURE 3-14 tor in the sizes and shapes required by the
Column form yoke spacing, inches. (Adapted from drawings.
1
U.S. Army Corps of Engineers, Concrete, Masonry and Provide a minimum distance of 1 2 in.
Brickwork.)
between reinforcing bars and the sides or
bottoms of forms, and 3 in. between the
rebar and the soil for slabs and footings. This will assure that the steel
is fully embedded in the concrete and protected from the corrosive
effects of moisture.

3.4.2 Placing Steel Reinforcing Mesh
Steel reinforcing mesh is a grid of steel wires welded together at the
wire intersections and used to distribute shrinkage stresses in thin
concrete sections like sidewalks and driveways. Light-gauge, welded
wire mesh comes in rolls and heavier-gauge mesh in flat sheets. Like
steel reinforcing bars, wire mesh reinforcing must be completely
embedded in concrete to develop full strength and structural bond,
and to provide adequate protection against corrosion of the metal.
Since reinforcing mesh is often used in thin 4-in. slabs for sidewalks
and patios, it is not always possible to place it as precisely as the rein-
forcing bars used in thicker slabs and footings. Reinforcing mesh is
usually located in the center of the concrete thickness with a mini-

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