TM 5-822-7/AFM 88-6, Chap. 8
free membrane and be maintained in this condition
19. Curing.
throughout the curing period. Unsatisfactory or
damaged areas will be resprayed. Any damage to the
cracking is caused by a combination of (1) high
membrane during the sawing operation will be
ambient air temperature, (2) high concrete
corrected by respraying. When forms are removed,
temperature, (3) low relative humidity, and (4) wind
the exposed faces of the concrete will be sprayed
velocity. These conditions need to be controlled
with curing compound.
when placing and protecting young concrete. It is
c. Substituting curing provisions. Where it has
essential that concrete be protected against the 10SS
been established from past experience in an area that
of moisture and rapid temperature change for the
membrane curing alone does not adequately protect
specified period of protection. All equipment,
pavement from shrinkage cracking, a combination of
material, and supplies for adequate curing and
moist curing and membrane curing may be specified.
protection of the concrete must be on hand and ready
d. Selection of curing material for pavements to be
to install before actual concrete placement begins. In
painted. In selecting curing material for pavement
general, curing will be accomplished by using a
pigmented membrane-curing compound. However,
surfaces to be painted, consideration will be given to
other methods may be specified if indicated by local
the necessity of sandblasting to remove coatings and
deposits that interfere with the bonding of paint.
conditions.
b. Membrane curing. The curing compound will be
Curing compounds of the low-melting-point wax-
base type tend to penetrate concrete and should not
applied by means of a power-driven machine
be used in the areas to be painted.
straddling the newly paved lane and operated so that
the spray will cover the pavement surface completely
20. Grade and surface-smoothness requirements.
and uniformly. Spray nozzles must be surrounded by
a hood to prevent wind from blowing the curing
a. Heliport and airfield pavements. The specified
compound spray. The rate of advance and spacing of
grade and smoothness requirements applicable to
nozzles of the spraying machine will be controlled so
airfield and heliport pavements are shown in table 8.
that a two-coat overlapping coverage will be provided.
The finished surfaces of airfield and heliport
Hand-operated pressure sprayers will be permitted
pavements shall have no abrupt change of 1/8 inch or
more and shall not deviate from the testing edge of
only on indicated odd widths and shapes of slabs and
an approved 12-foot straightedge more than the
on concrete surfaces exposed by removal of forms.
tolerances shown in table 8.
The curing compound must form a continuous void-
Table 8. Surface smoothness - airfield and heliport pavements
Tolerances
Direction
inches
Item No.
Pavement Category
of Testing
1/8
Longitudinal
1
Runways and taxiways
Transverse
1/4
Longitudinal
1/8
Calibration hardstands and compass
2
Transverse
1/8
swinging bases
Longitudinal
1/4
Other airfield and heliport areas
3
Transverse
1/4
c. Requirements for other vehicular pavements.
b. Road, street, and open-storage concrete
Parking area, motor-pool and motor-storage area,
pavements. Pavements shall be smooth and true to
repair- yard, and open-storage area pavements shall
grade and cross section. When tested with a 10-foot
be smooth and true to grade and cross section. When
straightedge on lines 5 feet apart parallel with the
tested with a 10-foot straightedge on lines 5 feet
centerline of the pavement, the surface shall not vary
apart parallel with and at right angles to the center-
more than 1/8 inch from the testing edge of the
line of the paved area, the surface shall vary not more
straightedge.
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