Hot Rubber Crack Filling in Champaign, IL
In most sealcoating markets crack filling is the supporting act. In Champaign it is the main event. The reason is in the ground: Champaign County is the type location for Drummer, the Illinois state soil, and for Flanagan, whose taxonomic class is fine, smectitic. Smectite is the clay mineral family that swells when it takes on water and shrinks when it dries, and Flanagan averages 35 to 42 percent clay in the particle-size control section. Drummer carries a seasonal high water table from January through May at depths ranging from half a foot above the surface to about a foot below it. When the base under a driveway changes volume twice a year, the pavement above it cracks, and those cracks are the doorway that lets the next round of water in. Filling them is the highest-return dollar in asphalt maintenance here.
The material matters. Hot-applied rubberized crack sealant is melted in a kettle to a specified temperature and poured or wanded into a cleaned crack, where it stays flexible through a wide temperature range and moves with the pavement instead of debonding from it. Cold pourable fillers out of a jug are convenient and have their place on hairlines, but they shrink as they cure, they harden over a couple of winters, and on a crack that is actively moving they typically pull away from one wall within a season. In a market with about 123.5 days a year at or below freezing, that difference shows up quickly.
Preparation is what separates a five-year fill from a one-year fill. Cracks get blown out with compressed air, and wider or ragged ones are routed to a consistent reservoir so the sealant has a defined shape and enough depth to flex. Vegetation gets pulled and the root zone treated, because a crack with grass in it will simply reopen along the root line. Sealant is filled slightly below flush or squeegeed flat rather than mounded, so a snow shovel or plow blade does not catch it. Cracks under about a quarter inch are usually left for the sealcoat to handle; anything wider gets filled.
Cracks worth filling now
Not every crack needs attention, and some are past the point where filling helps. Here is what to look for on a Champaign driveway or lot.
- Straight cracks running the length or width of the pavement, wider than about a quarter inch, with clean vertical walls.
- Cracks along the cold joint where two paving passes met, which tend to open first because the bond there was never as strong.
- Cracks around the perimeter, particularly at the garage apron and along the edge where the asphalt meets turf and the base is least confined.
- Any crack with grass or weeds growing out of it, because that means the crack is open to the subgrade and staying wet.
- Cracks that were filled two or more winters ago where the old material has hardened, shrunk, or pulled away from one wall.
Cracks that have branched into an interlocking web are a different problem. That pattern means the base under that area has lost support, and filling the web is a waste of sealant. Those areas need patching instead.
Which fill method fits the crack
Crack width and behavior drive the method. Getting this wrong is the most common reason a fill fails inside a year.
Under a quarter inch
Leave it for the sealcoat. Sealer will fill a true hairline adequately and forcing rubber into it creates a raised bead that catches shovels.
A quarter inch to about an inch
Clean, optionally rout, and fill with hot-applied rubberized sealant. This is the standard case and the one that returns the most value on Champaign clay.
Over an inch, or deep and irregular
Fill the void with a backer rod or sand slurry first, then seal the top. Pouring rubber straight into a deep void wastes a great deal of material and still fails.
Interlocking or alligator pattern
Do not fill. Saw-cut and replace the section. The failure is structural and sealant will simply follow the pattern down.
Whichever method applies, filling should happen before sealcoating rather than after, so the finished surface is continuous. See the driveway sealcoating page for how the two steps sequence together.
Hot Rubber Crack Filling FAQs
When is the best time to fill cracks in Champaign?
Spring and fall, when the pavement is at a middling temperature and the cracks are neither at their widest nor their tightest. Filling in the heat of July means the asphalt has expanded and the crack is at its narrowest, so you underfill and the sealant gets squeezed out in the next cold snap. Filling in a January thaw means the material will not bond to a cold wet wall. Late April through early June and again in September works well in central Illinois.
Do I need to crack fill every year?
On a residential driveway, no. Most need it on a two to four year rhythm, tied to the sealcoating cycle. On a commercial or multi-unit lot in Champaign, annual inspection and touch-up is reasonable because those lots see plow blades, heavier axle loads and more chloride. The point is not to fill the same crack repeatedly but to catch new ones while they are still narrow enough that filling them is cheap.