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A23.4-09
©
Canadian Standards Association
November 2009
22 Joints
22.1 General
22.1.1
If jointing materials are supplied and installed by the precast concrete manufacturer, the joints between
precast elements and the jointing materials shall be as specified by the owner and shown on the
installation drawings.
22.1.2
The following shall be shown on the installation drawings:
(a) joints between precast elements;
(b) joints between precast elements and other materials;
(c) jointing materials (if supplied and installed by the precast concrete manufacturer); and
(d) joint dimensions.
Note:
For information on the design of joints, see PCI MNL-122.
22.1.3
Joint width shall be sufficient to accommodate volume change movement tolerances for precast elements,
structure, and site placing of hardware. The owner shall specify the requirements for structure movement.
Joint widths shall also be chosen to ensure proper performance of joint material.
Note:
An adequate joint width is particularly important where the joints are the only means for accommodating installation
tolerances and building movements. See also
Clause 12
.
22.2 Construction joints
22.2.1 General
When a construction joint is to be made, the surface of the set concrete shall be suitably roughened,
thoroughly cleaned of foreign matter and laitance, saturated with water, and left damp, with no free water
on the surface, immediately before new concrete is placed. When a bonding agent is used, the surface
treatment shall be as recommended by the manufacturer.
Notes:
(1)
Precasting using multiple pours may be used when small parts intersect larger parts; such practices can decrease the
danger of unacceptable cracking.
(2)
When selecting a bonding agent, consideration should be given to the exposure conditions that will prevail during the
life of the structure.
22.2.2 Architectural joints
Joints between architectural precast concrete elements shall be constructed as shown on the shop
drawings. Joint materials shall be specified or reviewed by the owner.
Notes:
(1)
Samples of the joint materials for architectural precast concrete should be reviewed at the same time as the concrete
samples.
(2)
It is often advantageous to precast architectural elements with large returns in stages in order to cast exposed surfaces
horizontally and thus obtain a more uniform texture. The joints between exposed aggregate match-cast surfaces can
be hidden by locating them in a groove or a quirk return (for mitred joints).
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