shown. The concrete in these areas shall be carefully finished to provide
a surface of the same texture as the surrounding area that will be within
the requirements for plan grade and surface smoothness.
3.7
CURING
**************************************************************************
NOTE: Retain bracketed item at end of first
paragraph mandating 24 hour moist cure only where
locally required and only where approved by the
using service. Membrane curing should be the first
choice of curing methods.
**************************************************************************
3.7.1
Protection of Concrete
Concrete shall be continuously protected against loss of moisture and rapid
temperature changes for at least 7 days from the completion of finishing
operations. All equipment needed for adequate curing and protection of the
concrete shall be on hand and ready for use before actual concrete
placement begins. If any selected method of curing does not afford the
proper curing and protection against concrete cracking, the damaged
pavement shall be removed and replaced, and another method of curing shall
be employed as directed. Curing shall be accomplished by one of the
following methods [except that only moist curing shall be used for the
first 24 hours].
3.7.2
Membrane Curing
**************************************************************************
NOTE: The first option is for Army and Air Force
jobs; the second option is for Navy projects only.
**************************************************************************
A uniform coating of white-pigmented, membrane-forming, curing compound
shall be applied to the entire exposed surface of the concrete as soon as
the free water has disappeared from the surface after [finishing] [moist
curing ceases]. Along the formed edge faces, it shall be applied
immediately after the forms are removed. Concrete shall not be allowed to
dry before the application of the membrane. If any drying has occurred,
the surface of the concrete shall be moistened with a fine spray of water,
and the curing compound applied as soon as the free water disappears. The
curing compound shall be applied to the finished surfaces by means of an
approved automatic spraying machine. The curing compound shall be applied
with an overlapping coverage that will give a two-coat application at a
coverage of 10 square meters per L 400 square feet per gallon, plus or
minus 5.0 percent for each coat. A one-coat application may be applied
provided a uniform application and coverage of 5 square meters per L 200
square feet per gallon, plus or minus 5.0 percent is obtained. The curing
compound shall be applied with a single overlapping application that will
give a uniform coverage of 3.7 square meters/L 150 square feet per gallon.
The application of curing compound by hand-operated, mechanical powered
pressure sprayers will be permitted only on odd widths or shapes of slabs
and on concrete surfaces exposed by the removal of forms. When the
application is made by hand-operated sprayers, a second coat shall be
applied in a direction approximately at right angles to the direction of
the first coat. If pinholes, abrasions, or other discontinuities exist, an
additional coat shall be applied to the affected areas within 30 minutes.
Concrete surfaces that are subjected to heavy rainfall within 3 hours after
SECTION 02753
Page 67
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