Page 54 - Masonry and Concrete

Concrete Construction Techniques
53
CONCRETE CONSTRUCTION TECHNIQUES

TIE WIRE
STUD
WALE
PLYWOOD OR
LUMBER FORMS

STRONG BACK

FOOTING
FORM

BRACE
STAKE
FIGURE 3-13B
Bracing tall concrete forms (from U.S. Army, Concrete and Masonry. Technical Manual No.
5-742. U.S. Government Printing Office, Washington, D.C.).

3.4 Placing Reinforcement

After the excavations are completed and the forms built, steel rein-
forcement is put in place to provide tensile strength for the cured con-
crete. Wire reinforcing mesh is used for shallow elements like
sidewalks, patios, and driveways, and steel reinforcing bars are used
for heavier elements like footings, slabs, walls, and columns.

3.4.1 Placing Steel Reinforcing Bars
Reinforcing steel must be completely embedded in concrete to
develop full-strength and structural bond, and to provide adequate
protection against corrosion. To keep steel reinforcing up off the
ground or the bottom of the form so the concrete can surround it, use
small stones or pieces of concrete block or special wire stilts to sup-
port the bars or mesh (Figure 3-18). The reinforcement should be
located about one-third up from the bottom of the form. Where two
pieces of reinforcing bar must be spliced together, lap them 30 times

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