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A23.4-09
©
Canadian Standards Association
November 2009
13.1.12
Forms shall be sufficiently strong and stiff to carry concentrated loads resulting from cambering of
prestressed elements following the release of the prestress force.
13.1.13
Butt joints between form units making up the length of a casting bed shall match closely to minimize form
break lines on the elements.
13.1.14
Proper alignment of all form units shall be maintained during the entire casting operation.
13.1.15
Stress-resistant forms shall be designed and constructed in such a way that they are sufficiently stiff and
strong to withstand the prestressing forces and still maintain the required dimensional tolerances.
13.2 Forms for internal voids
13.2.1
Forms for internal voids shall have sufficient strength and stiffness to provide stability during handling and
placing of concrete and to withstand hydrostatic pressures and other forces during the production cycle.
However, the forms shall not be so stiff as to cause the concrete to crack because of the restraint of
shrinkage.
Notes:
(1)
Where new void designs are used, elements should be checked to ensure that void collapse or displacement has not
taken place and that no stress raisers have been created. When voids cannot be visually checked, actual concrete
quantities may be compared with theoretical quantities or the actual mass of an element may be compared with the
theoretical mass.
(2)
Storage conditions affect some void form materials and should be monitored so that a change in shape or a collapse
can be prevented.
13.2.2
The forming material shall not be adversely affected by moisture. The adequacy of the forms shall be
established before use.
13.2.3
Forms for internal voids shall be held in place during the placing and consolidation of the concrete in such
a way that their correct positions are maintained.
13.2.4
The anchoring devices to hold the voids in position shall be properly spaced to minimize the deflection
between anchor points and shall not puncture or otherwise damage the forms. Where void anchors are
attached to the reinforcement or prestressing tendons, displacement of the reinforcement shall be
prevented. Where removable templates are used, they shall remain in place for sufficient time after
concrete placement to ensure that the void is not displaced upon removal of the templates. However, the
concrete shall be sufficiently plastic that holes left by the template removal can be filled and the concrete
compacted into a homogeneous mass.
13.2.5
The ends and splices of void forms shall be sealed to prevent entry of cement paste or concrete.
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.