CEMP-E
TI 809-02
1 September 1999
Wall, Column, or Machine Foundation.
Isolation Joint 15 kg (30 lb.) Felt or
Expansion Joint Material
Floor Slab
Foundation
Figure 5-3. Isolation Joints
(3) Construction joints. Construction joints are used to allow separate concrete
placement. Construction joints should be kept to a minimum, and should generally be in
conformity with a predetermined joint layout. Construction joints will have dowels, or keys to
provide shear transfer. Dowel size and spacing should be in accordance with ACI Committee
302 Report, "Guide to Concrete Floor and Slab Construction." Formed-keyed joints will only be
used in slabs having a thickness of 150mm (6 inches) or more. In order to accommodate
keyed joints in 100 mm (4-inch) thick slabs it is acceptable to taper the slab so the slab at joint
locations is 150 mm (6-inches) thick. The taper should begin 1 meter (3 feet) each side of the
joint. Preformed keys left in place may be used for 100 mm (4 inch) and thicker slabs. The
key will be centered on the depth of the slab with the base of the male portion about one-third
the depth of the slab. Location and details of construction joints will be shown on drawings.
Details of construction joints are shown in Figure 5-4.
5-5
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