ITEM 258 DOWEL BAR RETROFIT
258.01
Description
258.02
Materials
258.03
Equipment
258.04 Construction
258.05 Method
of Measurement
258.06 Basis of
Payment
258.01 Description. This work consists of sawing slots
across transverse cracks, cleaning the slot, injecting caulking filler, placing
a dowel in the slot, and filling the slot with a patching material.
258.02 Materials. Furnish a one part silicone
sealant which does not require a primer for bond to concrete and conforms to
the following Table:
Properties |
Requirements |
Flow, ASTM
D5893 |
0.3 inches(7.6 mm) maximum |
Extrusion Rate, C1183 method A |
75 to 350 grams/minute |
Tack free time @ 77 °F ±3 °F (25 °C ±2 °C) –ASTM C679 |
20 to 90 minutes |
Specific Gravity - ASTM D 792, Method A |
1.010 to 1.515 |
Durometer Hardness - Shore A, cured 7 days @
77 °F ±3 °F (25 °C ±2 °C) and 45 to 55% R.H.; ASTM D 2240 |
10 to 25 at 0 °F (-18 °C) |
Tensile Stress -@ 150% elongation, 7 day cure @ 77 °F ±3 °F
(25 °C ±2 °C) and 45 to 55% R.H.; ASTM D 412, Die C |
45 psi (310 kPa)
maximum |
Elongation - 7 day cure @ 77 °F ±3 °F (25 °C ±2 °C) and 45
to 55% R.H.; ASTM D 412, Die C. |
800% minimum |
Bond to Concrete Mortar Briquettes - Air cured 12 days @ 77
°F ±3 °F (25 °C ±2°C);[1] |
50 psi (345 kPa)
minimum |
Movement Capability and Adhesion [2] |
Extend 100% and compress 50%; No
adhesive or cohesive failure after 10 cycles at 0 °F (-18 °C) |
Shelf Life |
9 months from date of shipment from
manufacturer |
[1]
Bond to Concrete Mortar Briquettes molded in accordance with AASHTO T 132 sawed in half and bonded with a thin
section of sealant and tested in accordance with AASHTO T 132. Briquettes will be dried to constant
weight in oven at 212 °F ±9 °F (100 °C ±5 °C).
[2]
Movement Capability and Adhesion: Prepare 1-inch × 2-inch × 3-inch (25
mm × 50 mm × 75 mm ) concrete blocks in accordance with ASTM C 719. A sawed face will
be used for bond surface. Seal 2 inches (50 mm) of block leaving 1/2 inch (13
mm) on each end of specimen unsealed. The depth of sealant will be 3/8 inch (10
mm) and the width 1/2 inch (13 mm). Subject sealant to
movement in accordance with ASTM
C 719. The magnitude of the movement will be as specified, and the
rate of extension or compression will be 1/8 inch (3.2 mm) per hour.
Furnish
materials conforming to:
Aggregate.........................................................
703.02.A.3
Curing
material........................................... 705.07, Type 2
Dowel
bars.............................................. 709.13 or 705.01
Dowel bar
chairs................ 709.14 or
non-metallic material
Preformed
filler........................................................ 705.03
Patching
material. Must meet the
performance requirements of ASTM
C928, Table 1, R3 concrete material with the following exceptions and
additions:
.... Final Set Time (ASTM C403)...... 25 minutes
minimum
.... Length Change (ASTM C157)
.... @ 4
days........................................... ±0.13% maximum
.... Freeze Thaw
Durability Factor (ASTM C666)
Procedure A @ 300 cycles or Procedure B @ 350 cycles,
.... Durability Factor:.................................... 90% minimum
Furnish
patching material according to the Departments Qualified
Products List (QPL)
Mix
prepackaged materials that contain all aggregates needed to produce the desired
concrete as specified by the manufacturer. For bagged cementitious
materials that need additional aggregates, grade the aggregate according to the
patching material manufacturer’s recommendation except ensure that 100% passes
the 1/2-inch (12.5 mm) sieve and a minimum of 85 percent, by weight, passes the
3/8-inch (9.5 mm) sieve.
258.03 Equipment. Furnish equipment to create slots that
has a power driven gang type assembly, consisting of diamond blade saws,
capable of sawing a minimum of three slots at one time to the required
dimensions, without damage to the surrounding pavement.
Furnish
jack hammers weighing less than 30 pounds (13.6 kg).
Furnish
abrasive blast equipment capable of removing the saw slurry or other foreign
material from the exposed surfaces leaving a clean, newly exposed concrete
surface free of spalls, laitance, and all contaminants detrimental to achieving
an adequate bond. Ensure water blasting pressure with abrasives in the
water is 10,000 psi (690 bar) or less.
258.04 Construction. The Engineer will locate and
mark cracks to be retrofitted. Provide the Engineer with aerosol spray
paint to mark the cracks to be retrofit.
Cut
2 1/2-inch (65 mm) wide slots into the pavement to a depth which places the
center of the dowel at mid-depth in the concrete slab. Make the slots
parallel to the centerline of the pavement. Make multiple saw cuts
parallel to the centerline if necessary to properly remove material from the
slot and to provide a level surface for the feet of the dowel bar chairs.
Cut three slots, on one foot (0.3 m) centers, in each wheel path, as shown in
the standard drawings.
Do
not allow traffic across the crack once the concrete has been removed from the
slots until all six retrofit dowel bars are in place, cured and
completed. Do not allow the tires of construction vehicles to travel on
slots where concrete has been removed.
Clean
the edge of the slots by approved blast methods to produce a rough
surface. Insure any blasting operation does not damage the surrounding
pavement. Do not begin abrasive blasting operations until implementing
reasonably available engineering controls to limit fugitive dust that are
acceptable to the Engineer. Conform to state, regional, and local
government agency requirements regarding control of dust generated by the
blasting operation.
Caulk
cracks at the bottom and sides of the slot with an approved silicone sealant in
order to prevent any grout from entering the crack. Apply the sealant
with a pressure applicator that forces it into the crack.
Place
a 1/2 inch (13 mm) thick preformed filler board to maintain the crack, as shown
in the plan details. Ensure the filler board fits tight around the dowel
and to the bottom and edges of the slot. Maintain the filler board in a
vertical position and tight to all edges during placement of the patching
material. Ensure the filler board extends from the bottom of the slot to
the surface of the pavement. If for any reason the filler board shifts
during placement of the patching material, redo the dowel bar retrofit at no
expense to the Department.
Ensure
the dowel bar chair firmly holds the bar centered in the slot. Obtain the
Engineer’s approval before using any dowel bar chairs. The Engineer will
reject any chair design that may allow movement of the bar during the placement
of grout.
Use
dowel bars 1 1/2 inches (38 mm) in diameter and 18 inches (460 mm) long.
Center the filler board on the dowel. Coat the dowel bars with a thin
uniform coat of new light form oil as a bond-breaking material just prior to
installation in the slot. Place an expansion cap on each end of the
dowels prior to installation. Ensure the expansion caps are tight fitting
and made of non-metallic material which will allow 1/4 inch (6 mm) movement at
each end of the dowel.
Use
two chairs to firmly hold the dowel bar in the slot during placement of the
patching material. Furnish chairs that are a nominal 2 1/2 inches (65 mm)
wide and center the dowel bar across the crack. Ensure the bar varies no
more than 1/4 inch (6 mm) from parallel to the pavement surface and the
centerline of the pavement. Just prior to placement of the patching
material, make one or more passes of an air blast to provide a dust-free, clean
slot to insure an adequate bond of the patching material.
Mix,
place, and cure the patching material in accordance with the manufacturer’s
recommendations. Consolidate the patching material using a vibrator approved
by the Engineer. Place the patching material in the slot and finish to
produce a smooth, even surface.
Repair
any damage to the pavement due to the Contractor’s operation at no expense to
the Department.
Cure
the patching material for a minimum of four hours before placing any vehicle
loads on the repair, or as directed by the Engineer.
258.05 Method of Measurement. The Department
will measure the quantity of Retrofit Dowel Bars by the actual number in the
complete and accepted work.
258.06 Basis of Payment. Payment is full
compensation for furnishing all materials including paint; sawing and cleaning
the slots; installing dowel chairs, dowels, bond breaker material, dowel bar end caps, sealant/caulking material, filler
material, and patching material.
The
Department will not pay for additional work or materials required due to
shifting of the filler board.
The
Department will not pay for any additional work to repair damage to the
pavement caused by the Contractor.
The
Department will pay for accepted quantities at the contract unit price as
follows:
Item
Unit
Description
258
Each
Retrofit Dowel Bar