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Canadian Standards Association
Precast concrete — Materials and construction
November 2009
13.2.6
When specified by the owner, void forms other than the solid type shall be drained. Where elements are
subjected to freezing temperatures, the voids shall be provided with drains at appropriate points.
Note:
When accelerated curing is used, consideration should be given to providing vents in void forms.
13.3 Preparation of forms
13.3.1
Forms shall be clean and shall be assembled within the dimensional controls established for the particular
set-up and element.
13.3.2
Form-release agents shall be
(a) applied uniformly;
(b) of a type consistent with the required finish;
(c) used at a rate suitable for easy release and stripping of the element; and
(d) compatible with any further treatment of the concrete surface.
Note:
The choice of form-release agents or surface retarders should be based on the form configuration, planned production
methods, the actual curing conditions, and any further treatment of the concrete surface.
13.3.3
The prestressing tendons, anchorages for miscellaneous connections, and reinforcement shall not be
contaminated by form-release agents, whether the form-release agent is applied before or after the
placing of the reinforcement and hardware.
14 Fabrication and placement of reinforcement
14.1 General
Fabrication and placement of reinforcement and prestressing tendons shall comply with Clause 6.6 of
CSA A23.1 and
Clauses 14.2
to
14.6
of this Standard.
14.2 Placing of tendons
The location of individual pretensioning tendons shall be shown on the shop drawings. At the ends, the
minimum clear spacing shall be 2-1/4 times the nominal diameter of the individual tendon, but not less
than 1-1/2 times the nominal maximum size of the coarse aggregate.
14.3 Placing of reinforcement
The size, shape, and spacing of all reinforcement shall be checked against the shop drawings. The
reinforcement shall be placed in the forms within the tolerances specified in
Clause 14.4
. Any variations in
spacing of reinforcement exceeding allowable tolerances shall be corrected.
Note:
To maintain tolerances and concrete cover requirements in intricate shapes or small concrete sections, cages should
be produced on a jig. Tack welding will normally result in additional cage rigidity and accuracy, but its use is restricted by
CSA W186, which describes the procedures to be followed when tack welding is performed.
14.4 Tolerances for placing
14.4.1
Reinforcement shall be placed within the following tolerances:
(a) for clear concrete protection or reinforcement: ±8 mm;
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