There are several factors that will impact the installation of your crack sealant material:
- Melter type can have an effect on sealant selection. Direct fire and gravity-fed machines may not always be compatible with all sealant types. It is important to read the manufacturer recommendations on all equipment to understand which sealants may or may not be appropriate for that specific unit.
- Agencies and contractors have been known to request higher quality sealant to make up for the lack of pavement cleaning. The obvious best practice is to clean well, but it should be noted that the higher property sealants require an even cleaner application to establish a good bond. Generally a lower performing sealant such as asphalt rubber, fiber-type material or a polyflex will work better for applications that are not well cleaned.
- Configuration plays a part too, such as whether the sealant being installed is in a reservoir/recess, or is flush vs an overband. In this case, the overband installation will require a stiffer product since it will be exposed to traffic unlike the flush installation.
- It is also common for some projects, like installs on a highway or high traffic area, to have insufficient traffic control. This means vehicles will have to drive onto the sealant before it has a chance to properly cool enough to resist pull-up. In this case, you may need to use a stiffer sealant that sets up quicker to be able to resist traffic earlier in the installation process.
How to Properly Install Crack Sealant
Because of its effectiveness, crack treatment has long been a popular preventative measure to keep moisture out of the pavement, preventing potholes from forming and extending pavement life. However, cracks that are not properly cleaned prior to repair simply cannot protect a pavement over the long term.
With summer in full swing, contractors should be encouraging crack sealing to their customers as a preventative maintenance service that must be completed before winter. Cracks sealed before winter help ensure the pavement is in the best possible state to endure the freeze/thaw cycles of the upcoming season and help to prevent further pavement damage.
Cleaning is Key
Aside from choosing the correct crack sealant, crack preparation this is the single most crucial determinant of success in a crack seal operation.
Many contractors begin with a general sweeping of the area with a sweeper or hand broom before crack sealing, but crack cleaning shouldn’t stop there. It is necessary to blow debris out of individual cracks with an air compressor, or even better, use a hot air lance. Each speck or crumb of dust, gravel or similar debris in the crack weakens the ability of the crack sealant to make the best bond with the surface. Further, if the bond between the sealant and crack walls isn’t tight, the slightest droplets of moisture seriously degrade the quality of the repair.
According to the Materials and Procedures for Sealing and Filling Cracks in Asphalt-Surfaced Pavement - Manual of Practice, contractors should follow these four guidelines when installing crack sealant:
- Apply the material with the nozzle in the crack channel, so that the channel is filled from the bottom up and air is not trapped beneath the material.
- Apply the material in a continuous motion, being sure to fill the channel to the proper level for recessed configurations or provide a sufficient amount of material for flush, capped, or overbanded configurations
- Reapply material to crack segments where material has sunk into the crack or an insufficient amount was furnished in the previous pass
- Recirculate material through the wand into the melting vat during idle periods.
The final step in crack sealing or filling is to finish and shape. To ensure the best finish possible, keep the squeegee close behind the application equipment. Keep the application equipment and the finishing squeegee centered over the crack channel. Periodically remove any material buildup from the squeegee.