"We like to see at least 100 psi of air to get the dust out of the little voids in the asphalt," he suggests.
Portable and stand-alone air compressors are available, as are air compressors integrated with the melter-applicator unit. In some cases, you may want to take a step further than air.
"Most cracks fail because of debris or moisture, so the next thing you might want to consider is a heat lance or a hot air lance," Dunn says. "Now you're not just running air but heated air, so you can actually heat the crack surfaces so the sealant adheres better and you're drawing any moisture out of the crack. This is especially effective in the mornings with dew, to get that moisture off the roadway before the sun comes up and dries it."
In areas where PM10 requirements restrict contractors from using blowers, Crafco offers the Crack-Vac as an alternative option. Manning says he sees this machine commonly used in crackfilling applications since cracksealing is most often performed on highways where these air restrictions wouldn't apply.
The care you put into crack preparation and the tools or combination of tools you use will affect the success of your crack treatment. Use your best judgment to decide what's best for your job.
The tested benefits of cracksealing
Of unsealed cracks, 75-80% developed additional cracks and potholes. Of sealed cracks, 1% developed additional cracks and potholes.
Unsealed cracks developed multiple cracks and spalling. Sealed, transverse crack condition remained stable with no spalling or secondary cracking. The conclusion: cracksealing retards deterioration and extends pavement by at least 4 years.
—Ontario Ministry of Transportation
For every $1 spend on pavement preservation maintenance programs, $4 to $10 was saved in rehabilitation. The earlier the preventative maintenance was applied, the lower the loss and higher the benefits.
Rehabilitation or reconstruction costs about 14 times as much as pavement preservation projects per lane mile over the life of the project.