shall be only as necessary to permit correct horizontal alignment to be
maintained. Any portions of the bottom layer of concrete that have been
placed more than 30 minutes without being covered with the top layer shall
be removed and replaced with newly mixed concrete without additional cost
to the Government. For pavements less than 300 mm 12 inches thick, the
reinforcement shall be positioned on suitable chairs securely fastened to
the subgrade prior to concrete placement. Concrete shall be vibrated after
the steel has been placed. Regardless of placement procedure, the
reinforcing steel shall be free from coatings which could impair bond
between the steel and concrete, and laps in the reinforcement shall be as
indicated. In lieu of the above, automatic reinforcement depressing
attachments may be used to position the reinforcement provided the entire
operation is approved by the Contracting Officer. Regardless of the
equipment or procedures used for installing reinforcement, the Contractor
shall ensure that the entire depth of concrete is adequately consolidated.
[If reinforcing for Continuously Reinforced Concrete Pavement (CRCP) is
required, the entire operating procedure and equipment proposed shall be
submitted for approval at least 30 days prior to proposed start of paving.]
3.5.8
Placing Dowels and Tie Bars
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NOTE: Delete references to slipform paving
installation of dowels and tie bars if slipform
paving is not allowed. Delete references to
installation in contraction joints if not required.
Delete bracketed references to tie bars, if tie bars
are not used.
**************************************************************************
The method used in installing and holding dowels in position shall ensure
that the error in alignment of any dowel from its required horizontal and
vertical alignment after the pavement has been completed will not be
greater than 3 mm per 300 mm 1/8 in. per ft.. Except as otherwise
specified below, horizontal spacing of dowels shall be within a tolerance
of plus or minus 15 mm 5/8 inch. The vertical alignment of the dowels
shall be measured parallel to the designated top surface of the pavement,
except for those across the crown or other grade change joints. Dowels
across crowns and other joints at grade changes shall be measured to a
level surface. Horizontal alignment shall be checked perpendicular to the
joint edge. The horizontal alignment shall be checked with a framing
square. Dowels [and tie bars] shall not be placed closer than 0.6 times
the dowel bar [tie bar] length to the planned joint line. If the last
regularly spaced dowel [tie bar] is closer than that dimension, it shall be
moved away from the joint to a location 0.6 time the dowel bar [tie bar]
length. Dowels shall be installed as specified in the following
subparagraphs.
3.5.8.1
Contraction Joints
Dowels [and tie bars] in longitudinal and transverse contraction joints
within the paving lane shall be held securely in place, as indicated, by
means of rigid metal frames or basket assemblies of an approved type. The
basket assemblies shall be held securely in the proper location by means of
suitable pins or anchors. At the Contractor's option, in lieu of the
above, dowels [and tie bars] in contraction joints shall be installed near
the front of the paver by insertion into the plastic concrete using
approved equipment and procedures. Approval will be based on the results
of a preconstruction demonstration which the Contractor shall conduct,
SECTION 02753
Page 61
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