Figure 2 .1.5, "effect of Concrete Temperatures, Relative Humidity, and
Wind Velocity on the Rate of Evaporation of Surface Moisture From Concrete"
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.
3.7.2.1
Application
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 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. Respray concrete
surfaces subjected to rainfall within 3 hours after the curing compound
application.
3.7.2.2
Protection of Treated Surfaces
Prohibit pedestrian and vehicular traffic and other sources of abrasion at
least 72 hours after compound application. Maintain continuity of the
coating for the entire curing period and immediately repair any damage.
3.7.3
Liquid Chemical Sealer-Hardener
Apply the sealer-hardener in accordance with manufacturer's
recommendations. Seal or cover joints and openings in which joint sealant
is to be applied as required by the joint sealant manufacturer. The
sealer-hardener shall not be applied until the concrete has been moist
cured and has aged for a minimum of 30 days. Apply a minimum of two coats
of sealer-hardener.
3.7.4
Curing Periods
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NOTE: Add the following if concrete will be under
water: [Cure structures submerged in fresh water
for a minimum of 12 hours prior to submerging. Cure
structures submerged in seawater for a minimum of 7
days prior to submerging.]
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Moist cure concrete using potable water for a minimum of 7 days. Continue
additional curing for a total period of 21 days. Begin curing immediately
after placement. Protect concrete from premature drying, excessively hot
temperatures, and mechanical injury; and maintain minimal moisture loss at
a relatively constant temperature for the period necessary for hydration of
the cement and hardening of the concrete. The materials and methods of
curing shall be subject to approval by the Contracting Officer.
3.7.5
Requirements for Type III, High-Early-Strength Portland Cement
The curing periods shall be not less than one-fourth of those specified for
portland cement, but in no case less than 72 hours.
SECTION 03311
Page 40
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