TM 5-822-7/AFM 88-6, Chap. 8
that the uncompacted edge cannot be consolidated
d. Compacting the end of a lane. When the end of a
lane is reached, the roller should roll off the end of the
with the fresher second lane. This happens when
there is some time delay between placement of
lane, rounding off the end in the process. This rounded
adjacent lanes such as at the end of the day's
end should be trimmed with a motor grader or with
construction. This hardening may take from one to
shovels to form a vertical face through the entire
several hours depending on properties of the
depth of the pavement. An alternative method
concrete and environmental conditions. Nevertheless,
involves confining the uncompacted end of the lane
the adjacent lane should be placed against the first
with a crosstie or beam anchored to the base course,
lane within90 minutes or be considered a cold joint.
thereby forming a vertical face at the end of the lane
b. Cold joint construction. Before placing fresh
after compaction.
concrete against hardened in-place pavement to
e. Proper roller operation. During the course of the
form a longitudinal cold joint, the edge of the in-place
vibratory compaction, the roller should never stop
pavement should be trimmed back to sound concrete
on the pavement in the vibratory mode. Instead, the
to form a vertical face along the edge. This vertical
vibrator should be turned on only after the roller is in
face should be dampened before the placement of the
motion and should be turned off several feet before
fresh lane begins. The height of the screed should be
the roller stops moving. The stopping points of suc-
set to an elevation approximately 25 percent higher
cessive rolling passes should be staggered to avoid
than the desired thickness of the compacted concrete.
forming a depression in the RCCP surface. The roller
The screed should overlap the edge of the hardened
should be operated at the proper speed, amplitude,
concrete lane 2 or 3 inches. The excess fresh concrete
and frequency to achieve optimum compaction. The
should be pushed back to the edge of the fresh concrete
best compaction will probably occur at a high
lane with rakes or lutes and rounded off so that a
amplitude and low frequency (because of the thick
lifts) and at a speed not exceeding 2 miles per hour.
minimal amount of fresh material is left on the surface
of the hardened concrete after compaction. The loose
f. Finish rolling. The vibratory compaction should
material should not be broadcast over the area to be
be followed immediately with two or more passes of
compacted; this may leave a rough surface texture
the pneumatic-tired roller so that the surface voids
after rolling. The edge of the fresh lane adjacent to
and fissures close to form a tight surface texture.
the hardened concrete should be rolled first, with
This rolling may be followed by a light dual-drum
roller to remove any roller marks on the surface, but
about 1 foot of the roller on the fresh concrete, to
form a smooth longitudinal joint (see fig D-4).
this will probably not be necessary. It is very impor-
Transverse cold joints are constructed in a similar
tant that all exposed surfaces of the RCCP be kept
manner. After cutting back the rounded-off edge
moist with a light water spray after the rolling
and wetting the vertical face, the paver is backed into
process until the curing procedure is implemented.
place and the screed set to the proper elevation using
shims sitting on top of the hardened concrete. The
D-11. Cold joints.
excess material should be pushed back as mentioned
a. General. A cold joint in RCCP is analogous to a
before, and a static pass made in the transverse
construction joint in conventional concrete pavement.
direction across the first 1 foot of the freshly placed
It is formed between two adjacent lanes of RCCP
lane. The joint should be carefully rolled to insure a
when the first lane has hardened to such an extent
smooth transition across the joint.
D-n
Previous Page
