TM 5-822-7/AFM 88-6, Chap. 8
meeting smoothness and grade requirements will be
than 1/4 inch from the testing edge of the straightedge.
repaired or replaced. High areas can be reduced by
d. Slipform paving edge slump. Edge slump is the
downward movement of the plastic concrete that
rubbing the freshly finished concrete with carborun-
occurs when the sliding form passes. Excessive
dum brick and water within 36 hours of the concrete
placement or by grinding the surface after it is 36
slump is indicative of improper concrete mixture
proportioning. If the concrete mixture cannot be
hours old. Generally, grinding should not exceed 1/4
redesigned to overcome the edge slump problem, fixed
inch in depth. The final surface of the repaired area
must retain the required skid resistance of the sur-
form paving should be used. When slipform paving
is used, 85 percent of the pavement will not have an
rounding pavement.
edge slump exceeding 1/4, inch, and 100 percent of the
23. Joints.
pavement will not have an edge slump exceeding 3/8 of
an inch. The area of pavement affected by this slump
a. General. Joints are constructed in concrete
will be limited to the outer 18 inches adjacent to the
pavement to permit contraction and expansion of a
slab edge.
pavement without irregular cracking and as a
construction expedient to separate the paved area
into strips necessary for handling and placing of
21. Tolerances in pavement thickness. Pavement will
concrete. There are three general types of joints:
be constructed to thicknesses indicated, and pave-
construction, expansion, and contraction.
ment thickness will be checked by measurements of
b. Construction joints.
cores drilled from the pavement as required by the
(l.) Longitudinal construction joints. These
contracting officer. Cores generally will be taken at
joints formed between paving lanes at the spacing
intervals of 2,000 feet or a fraction thereof from each
indicated will be either thickened edge, keyed, keyed
pavement lane of paved area where the lanes are
and tied, or doweled. The dimensions of the keyed
1,000 feet or more in length and from every other
lane of the paved area where the lanes are less than
joint are critical. It is essential that both key dimen-
sions and the location of the key in the joint conform
1,000 feet in length. Additional core drilling to
with details on drawings. Key dimensions are based
determine the extent of a pavement area deficient in
on pavement thickness with each thickness requiring
thickness will be included in the contract specification.
a different key size. When stationary forms are used,
Cores for checking pavement thickness will have a
metal molds for forming the keyway will be securely
diameter of no less than 4 inches. When cores are
fastened to the concrete forms so that molds will not
used for compressive-strength or splitting tensile-
be displaced by paving operations. When slipform
strength tests (ASTM C 496) as well as for checking
pavers are used to form keyed joints, the keyway
pavement thickness, a 6-inch-diameter core will be
shall be formed by means of pre-formed metal
drilled. Drilling and measurements of cores for
keyway liners, which are inserted during paving. The
checking pavement thickness will be done by the
metal liners may be shaped as they are fed through
Government. Costs of drilling and testing additional
the paver from continuous strips, or they may be
cores requested by the contractor will be borne by
pre-formed sections bolted together before insertion
the contractor. When the contractor is required to
through the paver. It is recommended that the metal
cut cores to check pavement thickness, additional
liners be left in place. When slipform pavers are used
core drilling requirements will be included in the
to form keyed and tied joints, bent tie bars shall be
contract specification. All core measurements will be
inserted into the plastic unconsolidated concrete
made by the contracting officer, and the cores will
through a metal keyway liner as described above.
become Government property.
The tie bars shall be straightened after the concrete
has hardened. The bent bars should be inspected to
22. Repairs of defective pavement slabs. Grooving
insure that the radius of curvature at the bend is
and sealing or epoxy sealing of random cracks, filling
equal to or greater than the specified minimum
of non-working contraction joints, repairing of
radius of curvature for the grade of steel being used.
spans along joints and cracks, and removing and
When stationary forms are used, all dowels will be
replacing of broken slabs that occur in non-reinforced
placed by the bonded-in-place method. Either one-
concrete pavements during construction will be
piece dowels or split dowels of the threaded type will
accomplished according to the requirements in the
be used. Dowels will be held accurately and securely
contract specification. Additional and supplemental
in place by fastening to the forms. When slipform
information is provided in TM 5-822-9. Areas not
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