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

FHWA TECHNICAL ADVISORY T 5080.14
June 5, 1990
(3) If it becomes necessary to pave a leave-out in hot weather,
the temperature of the concrete in the free ends should be
stabilized by placing an adequate layer of insulating
material on the surface of the pavement as described in
paragraph 4e(3)(a). The curing compound should be applied
to the new concrete in a timely manner. The insulation
material should remain on the adjacent pavement until the
design modulus of rupture of the leave out concrete is
attained.
9. Ramps. Auxiliary Lanes and Shoulders. PCC pavement for ramps,
auxiliary lanes, and shoulders adjacent to CRCP is recommended
because of the possible reduction in pavement edge deflections
and the tighter longitudinal joints adjacent to the mainline
pavement. Ramps should be constructed using jointed concrete
pavement. The use of jointed pavement in the ramps will
accommodate movement and reduce the potential for distress in
the CRCP at the ramp terminal. When PCC pavement is used for
ramps, auxiliary lanes, or shoulders, the joint should be
designed as any other longitudinal joint. Refer to the FHWA
Technical Advisory T 5040.29, Paved Shoulders, for further
information on proper joint design.
h. Widened Lanes. Widened right lane slabs should be considered
to reduce or eliminate pavement edge loadings. This is
discussed in the FHWA Technical Advisory T5040.29, "Paved
Shoulders".
5. CONSTRUCTION CONSIDERATIONS
a. Many CRCP performance problems have been traced to construction
practices which resulted in a pavement that did not meet the
previously described design recommendations. Because CRCP is
less forgiving and more difficult to rehabilitate than jointed
pavements, greater care during construction is extremely
important. Both the contractor and the inspectors should be
made aware of this need and the supervision of CRCP
construction should be more stringent.
b. Steel placement has a direct effect on the performance of CRCP.
A number of States have found longitudinal steel placement
deviations of 23 inches in the vertical plane when tube feeders
were used to position the steel. The use of chairs is
recommended to hold the steel in its proper location. The
chairs should be spaced such that the steel will not
permanently deflect or displace to a depth of more than l/2 the
slab thickness. An example chair device is shown in Figure 3.
3.6.10