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A23.4-09
©
Canadian Standards Association
November 2009
23.3.2
Extended curing, as specified in Clause 7.4.2.3.2 of CSA A23.1, shall be used when concrete strength
levels exceeding those achieved following initial curing are required for structural safety.
23.4 High-performance concrete curing (Types C-1 and C-XL concrete)
The curing procedures specified in CSA A23.1 shall be followed. However, alternative curing procedures
specific to a particular precast plant may be used if the procedures have been shown to produce a finished
concrete product that meets or exceeds all of the performance requirements for C-1 or C-XL concrete, as
applicable, specified in CSA A23.1. All testing and documentation shall be completed before the project
begins and shall be reviewed by the owner before the start of precast production.
Note:
See Tables 1 and 2 of CSA A23.1.
24 Treatment of unformed surfaces
24.1 General
The finishing of plastic concrete surfaces shall comply with Clause 7.5 of CSA A23.1 and
Clauses 24.2
to
24.3
of this Standard.
24.2 Finishing
Concrete surfaces that are to have concrete placed on them shall be clean and free of laitance.
24.3 Composite construction
The requirement specified in Clause 7.5.6.2 of CSA A23.1 for producing 5 mm deep grooves may be
waived for precast members, provided that interface shear is designed in accordance with
CAN/CSA-A23.3 for surfaces not intentionally roughened or if it can be shown by tests that the required
flexural and shear resistances can be developed without surface roughness.
Note:
See
(a) PCI
Manual for the Design of Hollow Core Slabs
; and
(b) Concrete Technology Associates,
Technical Bulletin
74-B6.
25 Toppings
25.1
Bonded concrete toppings used for rehabilitating existing concrete structures shall comply with Clause 7.6
of CSA A23.1. Bonded concrete toppings for new precast concrete construction shall comply with
Clause 7.6 of CSA A23.1, except as specified in
Clauses 25.2
and
25.3
.
25.2
The procedures for new precast construction specified in Clause 7.6.4.2.2 of CSA A23.1 for bonding
toppings to the base may be waived, provided that engineering analysis shows that the required level of
tensile or shear bond strength will be achieved.
25.3
Control joints shall comply with Clause 7.6.4.3.2 of CSA A23.1. Control joints, where required, shall be
located over longitudinal and transverse joints between precast concrete members,
Note:
The layout of control joints should be shown on the shop drawings. Consideration should be given to the shrinkage
characteristics of the topping mix when determining the number and spacing of control joints.
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.