3.5.3.1
Pigmented Curing Compound
A pigmented curing compound meeting the requirements of paragraph
MEMBRANE-FORMING CURING COMPOUND may be used on surfaces that will not be
exposed to view when the project is completed.
3.5.3.2
Nonpigmented Curing Compound
A nonpigmented curing compound containing a fugitive dye may be used on
surfaces that will be exposed to view when the project is completed.
Concrete cured with nonpigmented curing compound must be shaded from the
sun for the first 3 days when the ambient temperature is 32 degrees C 90
degrees F or higher.
3.5.3.3
Application
The curing compound shall be applied to formed surfaces immediately after
the forms are removed and prior to any patching or other surface treatment
except the cleaning of loose sand, mortar, and debris from the surface.
The surfaces shall be thoroughly moistened with water, and the curing
compound shall be applied as soon as free water disappears. The curing
compound shall be applied to unformed surfaces as soon as free water has
disappeared. The curing compound shall be applied in a two-coat continuous
operation by approved motorized power-spraying equipment operating at a
minimum pressure of 520 kPa 75 psi, at a uniform coverage of not more than
10 square meters/L 400 square feet per gallon for each coat, and the second
coat shall be applied perpendicular to the first coat. Concrete surfaces
that have been subjected to rainfall within 3 hours after curing compound
has been applied shall be resprayed by the method and at the coverage
specified. All concrete surfaces on which the curing compound has been
applied shall be adequately protected for the duration of the entire curing
period from pedestrian and vehicular traffic and from any other cause that
will disrupt the continuity of the curing membrane.
3.5.4
Impervious-Sheet Curing
Horizontal surfaces may be cured using impervious sheets. The sheets shall
comply with the requirements of ASTM C 171, except that polyethylene film
shall not be used. All surfaces shall be thoroughly wetted and be
completely covered with waterproof paper, or with polyethylene-coated
burlap having the burlap thoroughly water-saturated before placing.
Covering shall be lapped not less than 300 mm 12 inches and securely
weighted down or shall be lapped not less than 100 mm 4 inches and taped to
form a continuous cover with completely closed joints. The sheet shall be
weighted to prevent displacement so that it remains in contact with the
concrete during the specified length of curing. Covering shall be folded
down over exposed edges of the slabs and secured by approved means. Sheets
shall be immediately repaired or replaced if tears or holes appear during
the curing period.
3.5.5
Cold-Weather Curing and Protection
When the daily outdoor low temperature is less than 0 degrees C 32 degrees F,
the temperature of the concrete shall be maintained above 5 degrees C 40
degrees F for the first 7 days after placing. In addition, during the
period of protection removal, the air temperature adjacent to the concrete
surfaces shall be controlled so that concrete near the surface will not be
subjected to a temperature differential of more than 15 degrees C 25
SECTION 03372
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