item 423 CRACK SEALING, HOT APPLIED
423.01
Description
423.02
Materials
423.03
Equipment
423.04 Weather
Limitations
423.05
Preparation
423.06 Mixing
Type II and III
423.07
Application of Sealant
423.08 Opening to Traffic
423.09 Method of Measurement
423.10 Basis of Payment
423.01 Description. This work
consists of preparing and sealing pavement cracks with a hot applied crack
sealant.
423.02 Materials. Furnish hot
applied crack sealant, of the type specified, conforming
to:
Type I......................................................................
705.04
Type
II................................................................ 702.17.B
Type
III................................................................ 702.17.C
Type IV...............................................................
702.17.D
Obtain
the Laboratory’s approval of Type I crack sealant before shipping to the
project. Obtain approval of other crack sealants according to 702.17.
423.03 Equipment. Equipment used in the performance
of this work is subject to the Engineer’s approval and to the requirements of 108.05.
For Type I crack
sealant, heat the sealant in a kettle or melter
constructed as a double boiler, with the space between the inner and outer
shells filled with oil or other heat-transfer fluid. Use a kettle or melter with positive temperature control of the oil bath,
and provide a mixing vat, mechanical agitation, and recirculating pumps.
Do not apply direct heat to the sealant.
For Types II,
III, and IV crack sealants, heat the sealant in a kettle or melter
constructed as a double boiler, with the space between the inner and outer
shells filled with oil or other heat-transfer fluid. Use a kettle or melter with separate thermometers for the oil bath and
mixing vat. Equip the kettle with a full sweep type agitator. Also,
equip the kettle with a 2-inch (50 mm) minimum recirculating pump to provide
circulation of the materials when not applying the crack sealant. Do not
apply direct heat to the sealant.
For Types I and
IV crack sealants, use a mechanical applicator wand capable of continuously
feeding the sealant through nozzles shaped to penetrate the cracks. A
positive sealant flow shutoff mechanism is required. Ensure that the wand
produces a band according to the tolerances of 423.07.
For Types II and
III crack sealants, use a mechanical applicator wand head capable of placing
the crack sealant according to the tolerances of 423.07
while filling the cracks. A positive sealant flow shutoff mechanism
is required.
Use
portable air compressors capable of furnishing at least 100 pounds per square
inch (690 kPa) of air pressure at the nozzle.
Use compressors equipped with traps that maintain the compressed air free of
oil and water.
Use
water cleaning equipment capable of delivering water at 2000 pounds per square
inch (14 MPa) of pressure from a nozzle to the crack
being cleaned.
Use
a propane lance unit capable of producing a blast of hot air that operates at
1000 °F (538 °C) and a gas velocity of 2000 feet per second (600 m/s).
Use
mechanical and power driven routing and sawing equipment capable of following close
to the path of cracks and of widening the cracks to the required dimension
without causing excessive spalling or damage to the
adjacent pavement. For sawing equipment, use diamond saw blades with a
diameter of 8 inches (200 mm) or less.
423.04 Weather Limitations. Do not
seal cracks if the surface is visibly damp or the temperature is below 45 °F (7
°C).
423.05 Preparation. The contractor shall
fill all visible cracks per 423.07 or as
directed by the Engineer.
If
routing is specified, rout cracks with an opening less than 3/4 inch (19 mm) to
provide a sealant reservoir with a nominal size of 3/4 inch (19 mm) wide by 1
inch (25 mm) deep.
If
sawing is specified, saw all cracks to 3/4 to 7/8 inch (19 to 22 mm) wide and
7/8 to 1 inch (22 to 25 mm) deep. Use hand tools or a lightweight
chipping hammer to remove all slivers of asphalt concrete less than 1 inch (25
mm) wide remaining along the crack after sawing. Immediately before
sealing, sandblast both faces of the sawed crack to remove all contamination
and to texture the faces. If the crack below the sealant reservoir is
greater than 3/8 inch (10 mm) wide, insert a backer rod into the crack to form
the bottom of the reservoir at the proper depth.
Before
applying the hot sealant, clean cracks by an approved method or methods to
remove dust, dirt, moisture, vegetation, and other foreign material. Keep
the cracks clean and dry until all sealing operations are completed.
423.06 Mixing Type II and III. Use weigh tickets
in determining the specified proportion of fiber to blend into the
binder. Add fibers to the binder, and mix thoroughly in the kettle.
Do not allow the temperature of the sealant in the field application to exceed
the safe heating temperature recommended by the manufacturer. Do not heat
Type III crack sealant greater than 295 °F (146 °C).
423.07 Application of Sealant. Perform
the crack sealing operation within 250 feet (76 m) of the cleaning operation.
Seal
only cracks that are wide enough to permit entry of sealant. Seal tightly
closed cracks (less than 1/4-inch (6 mm) wide) only if they show signs of
raveling or spalling. Do not seal cracks
greater than 1-inch (25 mm) wide, and do not seal spalls or cavities greater
than 4 inches (100 mm) wide, unless otherwise directed.
For
Types I and IV crack sealants, fill the entire crack reservoir with the sealant
from the bottom up to approximately 1/16 inch (2 mm) above the pavement
surface. Immediately scrape the filled cracks with a V-shaped or U-shaped
squeegee, or similar hand tool, to smooth the overfill.
This may require more than one application of sealant. The Engineer will
not accept the work if the band of sealant on the pavement surface is greater
than 2 inches (50 mm) wide.
For
Types II and III crack sealants, place the sealant such that it fills the
cracks with a band of sealant within 2 to 4 inches (50 to 100 mm) wide.
The Engineer will not accept the work if the thickness on the pavement is
greater than 3/16 inches (5 mm).
423.08 Opening to Traffic. Do not
allow traffic on the sealant until it has cured and the possibility of tracking
no longer exists. However, if the Engineer determines it is necessary to
allow traffic to pass over the sealant before adequate curing, dust Portland
cement or other approved material over sealed cracks to eliminate pickup or
tracking.
423.09 Method of Measurement. The
Department will measure Crack Sealing, of the type specified, by the number of
pounds (kilograms) of hot applied sealant in place, completed, and accepted.
The
Department will measure Crack Sealing, of the type specified, by the square
yards of sealing completed and accepted.
423.10 Basis of Payment. The
Department will pay for accepted quantities at the contract prices as follows:
Item
Unit
Description
423
Pound (Kilogram)
Crack Sealing, Type I
or Square Yard
(Square Meter)
423
Pound (Kilogram)
Crack Sealing with Routing, Type I
or Square Yard
(Square Meter)
423
Pound (Kilogram)
Crack Sealing with Sawing, Type I
or Square Yard
(Square Meter)
423
Pound (Kilogram)
Crack Sealing, Type II
or Square Yard
(Square Meter)
423
Pound (Kilogram)
Crack Sealing, Type III
or Square Yard
(Square Meter)
423
Pound (Kilogram)
Crack Sealing, Type II or III
or Square Yard
(Square Meter)
423
Pound (Kilogram)
Crack Sealing, Type IV
or Square Yard
(Square Meter)