chapter 3 rigid pavement - DOT On-Line Publications - Department ...

(3) Transverse Construction Joints
FHWA TECHNICAL ADVISORY T 5050.14
June 5, 1990
(a) A construction joint is formed by placing a slotted
headerboard across the pavement to allow the
longitudinal steel to pass through the joint. The
longitudinal steel through the construction joint is
increased a minimum of one-third by placing 3-foot
long shear bars of the same nominal size between every
other pair of longitudinal bars. No longitudinal
steel splice should fall within 3 feet of the stopping
side nor closer than 8 feet from the starting side of
a construction joint. Refer to paragraph 4b(l)(e) for
recommended splicing patterns. If it becomes
necessary to splice within the above limits, each
splice should be reinforced with a 6-foot bar of equal
size. Extra care is needed to ensure both concrete
quality and consolidation at these joints. If more
than 5 days elapse between concrete pours, the
adjacent pavement temperature should be stabilized by
placing insulation material on it for a distance of
200 feet from the free end at least 72 hours prior to
placing new concrete. This procedure should reduce
potentially high tensile stresses in the longitudinal
steel.
(b) Special provisions for the protection of the
headerboard and adjacent rebar during construction may
be necessary.
f. Leave-Outs Temporary gaps in CRCPs should be avoided. The
necessity for leave-outs is minimized by giving proper
consideration to the paving schedule during project design. The
following precautions can be specified to reduce distress in
the leave-out portion of the slab in the event a leave-out does
become necessary. '.
(1) Leave-outs require 50 percent more longitudinal deformed
bars of the same nominal size as the regular reinforcement.
The additional reinforcement should be spaced evenly
between every other normal pavement reinforcing bar and
should be bonded at least 3 feet into the pavement ends
adjacent to the leave-outs. All regular longitudinal
reinforcement should extend into the leave-out a minimum of
8 feet. Required slices should be made the same as those
in normal construction.
(2) Leave-outs should be paved during stable weather conditions
when the daily temperature cycle is small. Because of the
closeness of the steel extreme care should be exercised in
placing and consolidating the concrete to prevent
honeycombing or voids under the reinforcement
3.6.9