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.
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 |
75-350 grams/minute |
|
Tack free time @ 77° F ± 3°F (25°C ±2°C) –ASTM C679 |
20-90 minutes |
|
Specific Gravity - ASTM D 792, Method A |
1.010-1.515 |
|
Durometer Hardness - Shore A, cured 7 days @ 77°F± 3° F (25°C ± 2°C) and 45-55% R.H.; ASTM D 2240 |
10-25 at 0°F (-18°C) |
|
Tensile Stress -@ 150% elongation, 7 day cure @ 77°F ± 3°F (25°C ±2°C) and 45-55% 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 45-55% R.H.; ASTM D 412, Die C. |
800% minimum |
|
Bond to Concrete Mortar: Briquets - Air cured 12 days @ 77° F ± 3°F (25°C ± 2°C);** |
50 psi (345 kPa) minimum |
|
Movement Capability and Adhesion *** |
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 |
|
**Bond to Concrete Mortar: Briquets 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. Briquets will be dried to constant weight in oven at 212° F ± 9°F (100°C ± 5°C). |
|
|
***Movement Capability and Adhesion: Prepare 1-inch x 2-inch x 3-inch(25 mm x 50 mm x 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, latence, and all contaminants detrimental to achieving an adequate
bond. Ensure water blasting 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 inch (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