423 Crack Sealing, Hot Applied

Description (423.01)

This work consists of cleaning and preparing pavement cracks and placing a hot crack joint sealant.


Materials (423.02)

The hot applied crack sealer must be the type specified on the plans and meet the requirements of 423.02.  Crack sealants are known as Type I, Type II, Type III, or Type IV.

Type I crack sealant must be approved by the Laboratory before shipping to the project.  Type II and III joint sealants are mixed on the project and require the use of PG 62-22 binder and fibers.  Binder is accepted based on a certification program while the fiber manufacturer must be on the Qualified Product List.  Type II can be a premixed and prepackaged sealant.  This type of sealant requires certified test data.

Type IV sealant is a prepackaged and preapproved mixture that requires the fiber manufacturer’s representative be present during the application to ensure proper application.  The Contractor must submit a 10 pound sample of the base binder and 10 pounds of fiber to the Laboratory for approval.


Equipment (423.03)

All equipment used for crack sealing must meet the Engineer’s approval and the requirements of 108.05.

Type I sealant must be heated in a kettle or melter constructed as a double boiler.  The space between the kettle and outer shell must be filled with oil or other heat-transfer fluid.  The melter must have temperature control of the oil and have a mixing vat, mechanical agitation, and recirculation pump.  Heat cannot be applied directly to the sealant.

Type II, III, and IV sealants must be heated in a double boiler as described above for Type I sealant; there must be separate thermometers for the oil and the mix vat.  A full sweep agitator and a minimum 2-inch recirculation pump must be used in the kettle.   Heat cannot be applied directly to the sealant.

For all sealant types, a mechanical applicator wand with a flow shutoff valve is required.  Nozzles on the wand must be shaped to penetrate the crack.

Air compressors are used to clean out the cracks prior to placing the sealant.  Air compressors must be a minimum of 100 psi and have water and oil traps.

Water cleaning equipment must deliver water at 2,000 psi to the crack being cleaned.

A propane lance that produces hot air and operates at 1,000 °F, with a gas velocity of 2,000 feet per second, must be used to dry the crack.

Routing and sawing equipment must be mechanical and power driven and capable of following the path of the crack and widening the crack to a desired dimension without causing spalling or damage to the adjacent pavement.  Saw blades must be diamond and 8 inches or less in diameter.


Weather Limitations (423.04)

The pavement surface must be dry (no visible moisture of any kind) and at least 45 °F (7 °C).


Preparation (423.05)

The Engineer determines the cracks to be sealed. 

If routing is required for cracks of less than 3/4 inch wide, rout cracks to an opening 3/4 inch wide by 1 inch deep.  This is the reservoir for the joint sealant

If sawing is required, saw cracks to 3/4 to 7/8 inch wide by 7/8 to 1 inch deep.  The slivers of asphalt concrete left behind that are less than 1 inch wide along the sides of the crack must be removed.  The Contractor can use hand tools or a light weight chipping hammer. Before sealing the crack, it must be sandblasted to remove contaminants and to provide a rough face so the sealant adheres to the walls of the crack.  If the crack below the saw cut is greater than 3/8 inches, a backer rod has to be pushed into the crack to form a bottom.

All cracks must be cleaned using an approved method, including water blasting and air blasting.  All dust, dirt, debris, moisture, and vegetation must be removed from the crack.  The prepared crack must be kept clean and dry prior to sealing. 


Mixing Type II and Type III (423.06)

Determine the proper proportion of fiber and binder to blend by using weigh tickets.  Check for thorough mixing.  Check the sealant temperature against the manufacturer’s recommendation and do not let it exceed this temperature.  Be sure the temperature of Type III sealant does not exceed 295 °F (146 °C) at any time.


Application of Sealant (423.07)

Fill cracks within 250 feet (76 m) of the cleaning operation. 

Seal cracks that are wide enough to allow injection of the sealant.  Tight cracks less than 1/4 inch wide are to be sealed only if they are raveling or spalling.  Do not seal cracks greater than 1 inch wide.  Do not seal spalls and cavities greater than 4 inches wide.

For Type I and IV sealants, fill the entire crack reservoir from the bottom to about 1/16 inch above the pavement surface.  The surface must be scraped immediately with a V-shaped or U-shaped squeegee to smooth the sealant at the surface.  The band that remains on the surface after smoothing must be less than 2 inches wide.  Wider bands must be rejected. 

For Type II and Type III sealant, the width of the band should be 2 to 4 inches, but never over 4 inches.  Do not accept the work if the band is too wide and/or the thickness of the sealant on the pavement surface is more than 3/16 inches (5mm).


Opening to Traffic (423.08)

Do not allow traffic on fresh sealant until it has cured and will no long pick up and track under traffic.  The Engineer may allow the use of an anti-tracking material if traffic must use the roadway.


Method of Measurement (423.09) and Basis of Payment (423.10)

Crack sealing is measured by the number of pounds of hot applied crack sealant in place and accepted.


Documentation requirements - 423 Crack Sealing Hot Applied

1.      Document that the materials are on an approved list, have certified test data, and/or have been sampled as required.

2.      Document type of sealant used (Type I, Type II, Type III, Type IV) and mixing methods.

3.      Document the proper crack preparation procedures, including routing, sawing, and cleaning. 

4.      Document pavement conditions and air temperature.

5.      Document when the pavement is opened to traffic and any observations regarding sealant pick-up or tracking. Document and determine weight of sealant for pay.  Use weight tickets only.