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Canadian Standards Association
Precast concrete — Materials and construction
November 2009
13.1.3
Parts such as bulkheads, side or top forms, or form modification pieces shall be well fitted and secured and
joints shall be sealed to prevent leakage.
13.1.4
Forms shall be fabricated to allow stripping without damage to the precast element.
13.1.5
Form braces shall not touch the concrete for any finish better than smooth form finish, as described in
Clause 6.5 of CSA A23.1, unless reviewed by the owner.
13.1.6
Forms shall be clean, well maintained, and checked to ensure that elements of the required quality are
produced.
Notes:
(1)
The manufacturer should identify the specific form or forms in which an element was cast so that appearance and
dimensional problems can be identified.
(2)
Tolerances for forms should be one-half those specified for the dimensions of the finished element in
Clause 12
.
13.1.7
Joints in the form material shall be made in such a manner that they will not be reflected in the concrete
surface and mar the appearance of the product.
13.1.8
Repeated casting, consolidation of concrete, and stripping of elements shall not affect the dimensions or
the planes of the elements beyond the allowable tolerances.
Notes:
(1)
It is important that window openings be made accurately. For glazing directly to the concrete, the plane of the opening
should meet the tolerance requirements during the entire casting and curing cycle.
(2)
Corners of precast concrete elements that are exposed to view should normally be rounded. Lines and shapes should be
true and uniform.
(3)
Whenever possible, forms should have sufficient draft to facilitate stripping with a minimum of form breakdown.
(4)
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.
13.1.9
Forms shall permit fixed positioning or jigging of hardware and allow for accurate positioning of the
reinforcing cage while maintaining the specified cover to the reinforcement. In architectural concrete,
spacers shall not be used between the reinforcing and those surfaces that will be exposed to view.
Notes:
(1)
When spacers are necessary for unusual products, their use and type should be reviewed by the owner.
(2)
Forms may be made of wood, steel, concrete, plastic, rubber, or a combination of these materials. The choice of
material should be the manufacturer’s, provided that this does not compromise the quality of the finished product
specified by the owner.
13.1.10
When forms are being prepared for concrete, form-release agents and surface retarders shall be applied
uniformly.
13.1.11
Forms shall allow for shortening and movement of the precast elements during the transfer of prestress
and for the application of heat when accelerated curing is used.
Licensed for/Autorisé à Jed Friesen Sold by/vendu par CSA on/le June/18/2015.
~Single user license only. Storage, distribution or use on network prohibited. Permis d'utilisateur simple seulement.
Le stockage, la distribution ou l'utilisation sur le réseau est interdit.