3.9.1.2
Fog Spraying or Sprinkling
Apply water uniformly and continuously throughout the curing period. For
temperatures between 4 and 10 degrees C (40 and 50 degrees F) 40 and 50
degrees F, increase the curing period by 50 percent.
3.9.1.3
Pervious Sheeting
Completely cover surface and edges of the concrete with two thicknesses of
wet sheeting. Overlap sheeting 150 mm (6 inches) 6 inches over adjacent
sheeting. Sheeting shall be at least as long as the width of the surface
to be cured. During application, do not drag the sheeting over the
finished concrete nor over sheeting already placed. Wet sheeting
thoroughly and keep continuously wet throughout the curing period.
3.9.1.4
Impervious Sheeting
Wet the entire exposed surface of the concrete thoroughly with a fine spray
of water and cover with impervious sheeting throughout the curing period.
Lay sheeting directly on the concrete surface and overlap edges 300 mm (12
inches) 12 inches minimum. Provide sheeting not less than 450 mm (18
inches) 18 inches wider than the concrete surface to be cured. Secure
edges and transverse laps to form closed joints. Repair torn or damaged
sheeting or provide new sheeting. Cover or wrap columns, walls, and other
vertical structural elements from the top down with impervious sheeting;
overlap and continuously tape sheeting joints; and introduce sufficient
water to soak the entire surface prior to completely enclosing.
3.9.2
Liquid Membrane-Forming Curing Compound
Seal or cover joint openings prior to application of curing compound.
Prevent curing compound from entering the joint. Apply in accordance with
the recommendations of the manufacturer immediately after any water sheen
which may develop after finishing has disappeared from the concrete
surface. Provide and maintain compound on the concrete surface throughout
the curing period. Do not use this method of curing where the use of
Figure 2.1.5 in ACI 305R indicates that hot weather conditions will cause
an evaporation rate exceeding one kg pf water per square meter per hour
(0.2 pound of water per square foot per hour) 0.2 pound of water per square
foot per hour.
3.9.2.1
Application
Unless the manufacturer recommends otherwise, apply compound immediately
after the surface loses its water sheen and has a dull appearance, and
before joints are sawed. Mechanically agitate curing compound thoroughly
during use. Use approved power-spraying equipment to uniformly apply two
coats of compound in a continuous operation. The total coverage for the
two coats shall be 5 square meters maximum per L (200 square feet maximum
per gallon) 200 square feet maximum per gallon of undiluted compound unless
otherwise recommended by the manufacturer's written instructions. The
compound shall form a uniform, continuous, coherent film that will not
check, crack, or peel. Immediately apply an additional coat of compound to
areas where the film is defective. Re-spray concrete surfaces subjected to
rainfall within 3 hours after the curing compound application.
3.9.2.2
Protection of Treated Surfaces
Prohibit pedestrian and vehicular traffic and other sources of abrasion at
SECTION 03300N
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