The allowable procedures for
the repair of metalized and galvanized surfaces are described in C&MS Item 711.02,
which refers the reader to ASTM-A-780. The use of a galvanizing spray with zinc dust
is not allowed. These unacceptable
products go by the name of Spray Galv or Cold
Galv. The main problem with these
products is that they don’t provide the galvanic protection that is
required. Most of them are made out of
tin and lead in place of zinc. When zinc
and carbon steel are in contact, the zinc sacrifices itself to protect the
steel. Conversely, when tin or lead are
in contact with the steel, the steel sacrifices itself for the tin and lead.
It is important that the gap
set between the armor plates of the joint be consistent along the entire length
of the joint. The gap determined for the
joint must be adjusted for temperature.
The joint manufacturer will supply a table to help calculate this
adjustment. This is especially true for
more complex joints.
The characteristics of the
structure (e.g., skew, crown, super elevation, sidewalk, etc.) can lead to a
complicated installation of the joints.
The Contractor should not weld anything to the joint or the reinforcing
steel.
Joints, like strip seal,
compression, and modular, which incorporate a rubber seal into their design,
need to have the seals installed per the manufacturer’s written
instructions. They should utilize tools
that will not cut or puncture the seals.
It is not acceptable to elongate or stretch the seal in order to make it
narrow enough to fit in the joint gap.
For
Integral and Semi-Integral Abutment Expansion Joint Seals, the Contractor must
install a 3-foot wide neoprene sheet for waterproofing the backside of the
joint between the integral backwall and the bridge
seat at locations shown in the plans. The neoprene sheeting is secured to the
concrete with 1-1/4 inch by No. 10 gauge (length × shank diameter) galvanized
button head spikes through a 1-inch outside diameter, No. 10 gauge galvanized
washer. Maximum fastener spacing is 9 inches. Use of other similar galvanized
devices, which will not damage the neoprene or the concrete, will be subject to
the approval of the Engineer. The neoprene sheeting shall be 3/32-inch thick
general purpose, heavy-duty neoprene sheet with nylon fabric reinforcement.
There are listings on the Qualified
Product List (QPL) for items covered in C&MS
Items 705.11
and 705.03. This list is maintained by the Office of
Materials Management.
In addition to the protection
required in the specification, the Contractor must ensure that the sawcut is not exposed to traffic prior to receiving the
sealer without protecting the sawcut. If the sawcuts are
not protected, rocks or other hard debris can get lodged in the top of the sawcut, and when driven over the rock, will spall the edges
of the sawcut.
Note: If the beam seats are
low and elastomeric bearings are utilized, it is not acceptable to use steel
shims under the bearing to make up the elevation difference. Elastomeric bearing pads are to set directly
on the concrete surface. If the beams seats are sealed with an epoxy or non-epoxy sealer prior
to setting the bearings, do not apply sealer to the concrete surfaces under the
proposed bearing locations. If these locations are sealed, the Contractor must
remove the sealer to the satisfaction of the Engineer before setting the
bearings. Contact the Office of
Structural Engineering for guidance.
Many of the bearings have beveled load plates. This is done to account for the grade in the
structure. Make sure the beveled
bearings are oriented correctly.
Sometimes it is difficult to tell simply by looking at the bearing, as
the difference may only be a 1/4 inch.
If the short side of the bearing is not already marked by the
fabricator, measure the bearing and mark it in the field.
The Contractor must position rockers, elastomeric bearings, and rollers so
that, when the completed bridge is at 60 °F (16 °C), the rockers and elastomeric bearings are vertical and the rollers
are centered on the base. If the steel is erected at an ambient temperature higher than 80 °F
or lower than 40 ºF and the bearing shear deflection exceeds 1/6 of the bearing
height at 60 ºF ± 10 ºF, the Contractor must raise the beams or girders to
allow the elastomeric bearings to return to their undeformed
shape at 60 ºF ± 10 ºF.
Where
the load plate of an elastomeric bearing is to be connected to the structure by
welding, the Contractor must control the welding so that the plate temperature
at the elastomer bonded surface does not exceed 300 °F as determined by use of pyrometric sticks or other temperature monitoring devices.
When galvanized bearings are
welded to the embedded load plates on prestressed
beams, the weld area must be repaired according to C&MS Item 516.03.
There is a listing on the Qualified
Product List (QPL) for items covered in C&MS
Item 711.21. This list is maintained by the Office of
Materials Management.
1. Expansion and Contraction Joints.
a. Expansion material placed and measured in appropriate
unit per C&MS 516.08
and 516.09.
b. Shop drawings per C&MS 501.04.
c. Test Reports per 501.06.
2. Joint Sealer.
a. Area to be sealed clean and dry.
b. Document depth of poured joints.
c. Note types of bond breakers and bonding agents used.
d. Sealers applied per manufacturer’s directions.
e. Measure and pay in appropriate unit.
3. Bearing devices.
a. Shop drawings per C&MS 501.04.
b. Test Reports per 501.06.
c. Sliding plates lubricated with flake graphite.
d. Lead sheets and bearing pads set to line and level.
e. Rockers and rollers set vertical at 60 °F (16 °C) or adjusted for temperature.
f. Anchor bolts placed to proper depth and alignment and
set in mortar.
g. Record quantity(s) and pay in appropriate unit(s) per
C&MS 516.09.