Cracks are going to happen in asphalt pavement, and when they do it's your job to stop them from deteriorating the surface and creating potholes. Debris and moisture are the two biggest enemies facing the success of a crackfilling or cracksealing job. Proper preparation of a crack will extend the life of the crack repair.
To seal or fill
Crackfilling and cracksealing are two different techniques. Many people in the industry use the terms interchangeably, but there are important differences to keep in mind when considering these two methods.
In short, crackfilling is performed on cracks with little movement, meaning they don't open up in winter and close in the summer. These cracks are generally longitudinal (cracks that run up and down a road), block cracks, and some closely spaced transverse cracks.
Cracksealing is often performed on "working cracks," or cracks that get wider in the winter and smaller in the summer. These are often transverse cracks, or cracks that run across a road.
"Basically what we're trying to accomplish with cracksealing is a 5- to 7-year lifespan sealing job with a very flexible, elastomeric sealant. With crackfilling we're trying to get a 2- to 5-year lifespan, basically waterproofing and gluing that usually narrow crack," explains Mark Manning, vice president with Crafco Inc. "Crackfilling is more of a maintenance issue; cracksealing is more of a preservation function."
Manning says cracksealing should be done on pavements with fairly minimal cracking, less than 20%. When the concentration of cracks exceeds 20%, the damage is more likely due to pavement deterioration, such as oxidation or fatigue cracking.
"All pavements will crack sometime or another, and if you catch the cracks when they're less than 20%, then you're more likely to be able to seal them and have the procedure last 5 to 7 years," he says.
Brad Dunn, vice president of sales at Cimline, says cracksealing is best done early in the life of a pavement, in the first 1 to 3 years.
"You'd probably want to follow up every other year because you probably will have some secondary cracks that form off the primaries. The real key thing is the earlier the better," he says.
Cracksealing involves routing out a crack, which will give you intact asphalt sides for the sealant to adhere to. Crack routers are walk-behind machines that use carbide cutters to form a reservoir for the crack sealant. The configuration of the reservoir depends on how much your crack moves.
"You have two routing configurations — one is wider and narrower, and that's to accommodate 50% or more movement. And then you have a traditional 1 to 1 configuration which would be about a half-inch deep and a half-inch wide, for 50% or less movement," Manning explains. "That wide narrower one can go out to 2 inches wide to 3/8ths of an inch deep. That would be used in the very cold climates where the cracks are moving tremendously, like 100% or better."
Other common routing configurations are ½ inch by ½ inch, ¾ inch wide by ½ inch deep, and ¾ inch by ¾ inch.
Cleaning for a crackfill is very basic. Since the routing step is skipped, you need to find another way to remove dirt and debris from the crack.
Some contractors prefer to employ the help of a wire brush in their crack preparation routine. These machines utilize a small motor that powers an upturning wire brush to rip vegetation and debris out of a crack. It also burnishes the sidewalls of the crack to help improve sealant adhesion.
"Billy Goat constructed the Grazor with heavy-duty caster wheels that swivel a full 360 degrees, so you can maneuver the Grazor with ease as it rips through ragged cracks at the rate of 5 feet every 15 seconds," says Melinda Thurston at Billy Goat Industries, Inc.
Whether you've routed or wire brushed a crack, you will need to use air to further clean. Backpack blowers and pavement blowers are common tools that contractors use for crackfilling and sealing, but Manning suggests higher-powered air.