TM 5-822-7/AFM 88-6, Chap. 8
material in each size category, the approximate
asphalt emulsion. The curing compound or emulsion
proportions of coarse aggregate, fine aggregate, and
must form a continuous void-free membrane and
cement and fly ash combined may be determined and
should be maintained in that condition throughout
checked against predetermined limits.
the curing period. An irrigation sprinkler system has
c. Field density tests. Field density tests should be
been used to cure RCCP in Canada and at Fort
performed on the RCCP using a nuclear density gage
Lewis, but caution should be exercised so that the
operated in the direct transmission mode according
fines in the surface of the RCCP are not washed away
by excessive spraying.
to ASTM D 2922. At least one field reading should
b. Moist curing. Continuous moist curing of the
be taken every 100 feet of each paving lane. The
readings should be taken as closely behind the rolling
RCCP for at least 7 days should be considered if frost
resistance is a concern. Preliminary results of labora-
operation as possible. The reading should be adjusted
using the correlation determined in the test section
tory freezing and thawing tests indicate that RCCP
construction and checked against a specified density.
which has a sufficiently low water-cement ratio and
Areas that indicate a deficient density should be
has been moist cured for an extended period tends to
rolled again with the vibratory roller until the
be more frost-resistant. The improved frost
resistance may be due to more complete hydration
specified density is achieved.
d. Obtaining core samples. The acceptance criteria
resulting in a reduction in fractional volume of
for the strength, density, and thickness of RCCP
freezable water at saturation.
shall be based on appropriate tests conducted on
c. Early loading. All vehicular traffic should be
cores taken from the RCCP. Cores should be taken
kept off the RCCP for at least 14 days. If it is
from the RCCP when the pavement is 7 days old.
absolutely necessary, a water-spraying truck and
One core should be taken at every fifth nuclear gage
membrane-spraying truck may be driven onto the
density test site, within a 1- to 3-foot radius of the
RCCP before that age, but this practice should be
test hole. The density and thickness of the core
kept to a minimum.
should be measured, and the core should be field
D-13. Quality control/assurance.
cured under conditions similar to the RCCP curing
a. General. Quality control and quality assurance
conditions. The cores should be tested for splitting
consist of testing of materials going into the
tensile strength (ASTM C 496) when they are 28
concrete; checking the plant calibration regularly;
days old.
measuring the in-place density of the RCCP using a
e. Smoothness. The finished surface of the RCCP
nuclear density gage; checking the smoothness of
should not vary more than 3/8 inch from the testing
the finished RCCP with a straightedge; taking core
edge of a 10-foot straightedge. Smoothness should
samples from the RCCP for measurement of density,
be checked as closely behind the finish roller as
strength, and thickness; and, if desired, fabricating
possible, and any excessive variations in the surface
RCC cylinders and beams.
shall be corrected with the finish roller. Particular
b. Tests at plant. Moisture contents of the fine and
attention should be paid to the smoothness across
coarse aggregates should be determined daily as
fresh and cold joints because this is usually a critical
necessary and appropriate changes made in the
area for surface variations. A skilled vibratory roller
amount of mixing water. Washed gradation tests
operator is essential in minimizing smoothness
should normally be performed on the combined
problems. The final surface texture of the RCCP
aggregates three times per day: in the morning, at
should resemble that of an asphalt concrete pave-
midday, and in the afternoon. The samples should be
ment surface.
taken from the conveyor before the cement or fly ash
f. Cylinder and beam fabrication. The fabrication
is added to the combined aggregates. The amount of
of cylinders and beams during RCCP construction
materials passing the No. 100 sieve should be deter-
would be highly desirable as (1) an aid to the coring
mined during this analysis. After each gradation
operation in checking the RCCP strength and density,
test, a washout test according to procedures in
and (2) a means of establishing a data base for
ASTM C 685 (para 6.5) may be performed on the
developing future quality control criteria. If fabricated
combined dry ingredients on samples taken from the
cylinders and beams are to be used as a quality control
conveyor belt between the cement and fly ash hoppers
aid during construction, a correlation between their
and the pugmill. By washing the dry ingredients
strength and density and that obtained from cores
over the No. 4 and No. 100 sieves and weighing the
and sawed beams should be made during test section
D-14
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