Asphalt repair in Houston: find the cause, then fix the pavement

Read the damage before choosing the repair

A contractor worth hiring will walk the pavement and name the type of distress before talking about fixes. Different cracks and depressions come from different causes, and the right repair for one is a waste of money on another.

The questions to answer are simple. Is the problem only in the top inch or two, or does the pavement move under a heavy wheel? Is it isolated to one spot, or spread across a whole wheel path or section? Is water involved, either standing on the surface or pumping up through cracks after rain? Is there a tree, a downspout, a dumpster pad or a truck route nearby that explains why it failed there and not elsewhere?

Once the cause is clear, the repair usually picks itself. The sections below walk through the common failures on Houston-area driveways, private roads and lots.

Potholes and alligator cracking: failures below the surface

Alligator cracking, also called fatigue cracking, looks like a tight network of small interconnected blocks, similar to reptile skin. It shows up in wheel paths, at dumpster pads, at drive-throughs and where delivery trucks turn. It means the pavement has been bending too much under load, usually because the base or the clay under it is soft. On gumbo subgrade after a wet stretch, that softening can happen quickly.

Left alone, those small blocks loosen, traffic plucks them out, and a pothole forms. Heavy rain then fills the hole, softens more of the base, and the hole widens. Potholes that appear right after a tropical storm or a week of rain are usually the final stage of alligator cracking that had been there for a while.

Because the problem is structural, a surface treatment will not fix it. Sealcoat over alligator cracking hides it for a few weeks at most. The repair is removing the failed pavement, repairing or rebuilding the base, and patching full depth.

Block cracking, raveling and aged surfaces

Block cracking forms large rectangles, often a foot or more on a side, across areas that see little traffic as well as heavy traffic. It comes from the binder getting old and stiff and shrinking as temperatures swing, not from loads. Under long Houston summers, UV and heat oxidize the surface, which turns it from black to gray and makes it brittle.

Raveling is the surface wearing away: fine material disappears first, then larger stones loosen and scatter, leaving a rough, pitted texture. It points to aged binder, poor compaction when the pavement was built, or both.

These are surface problems, and they are the ones maintenance treatments can address. Crack sealing, sealcoating on moderately aged surfaces, and eventually a mill and overlay are the usual steps. If the pavement is also soft or cracking in wheel paths, it is more than an aging problem.

Rutting, shoving and edge failure

Rutting is a depression running along the wheel paths. In the Houston area it often forms in two ways. One is the asphalt itself deforming in summer heat where heavy vehicles stop, start and turn slowly, such as at a gate, a loading area or the approach to a dumpster. The other is the base or clay compressing under repeated loads, which shows as wider, deeper ruts often accompanied by cracking.

Shoving is a washboard or bulge where the surface has been pushed sideways, typically where vehicles brake or turn sharply. It points to a mix that was too soft for the traffic, too much binder, or a top layer that has slipped because it was never stuck well to the layer beneath.

Edge failure is crumbling and breaking along the unsupported side of a drive or private road. It happens where there is no curb, where the stone base stops short of the edge, where water runs off the pavement and softens the shoulder, and where tires regularly drop off the side. Tree roots lifting the edge are a related cause on shaded drives.

Minor heat rutting at a stop can be milled and repaved with a stiffer mix. Base-related rutting and edge failure need the base fixed, and edges need a proper shoulder or curb, or they will break again.

Cold patch, hot mix patch and full-depth repair

These three words get used loosely, so it helps to know what each one actually means.

Cold patch is bagged or bulk asphalt that stays workable at air temperature. It is shoveled into a hole and tamped. It is a useful temporary fix, especially after a storm when a hole is a hazard and asphalt plants may be slow to reopen, but it rarely lasts long in a hole that holds water or takes truck traffic.

A hot mix surface patch uses plant-produced asphalt placed and rolled while hot. When the damage is only in the top layer, the contractor cuts or mills out the damaged surface, cleans it, applies tack, fills with hot mix and compacts it level with the surrounding pavement.

A full-depth patch is the proper repair for alligator cracking and potholes caused by base failure. The contractor saw-cuts square edges around the failed area plus a margin of sound pavement, removes the asphalt and the soft base, compacts or replaces the subgrade, rebuilds the base with crushed stone, applies tack to the vertical edges, and paves in lifts. It costs more per spot than a surface patch because it is fixing the real problem.

1. Mark out the failed area with a margin of sound pavement around it
2. Saw-cut straight, vertical edges
3. Remove asphalt and any soft, wet base material
4. Compact the subgrade and rebuild the base in layers
5. Tack the edges and pave hot mix in lifts, rolling each one
6. Seal the edges of the patch so water cannot follow the joint

Infrared repair and where it fits

Infrared repair uses a heater to soften a section of existing asphalt in place. The crew rakes the heated material, adds fresh hot mix and a rejuvenating agent as needed, and rolls it smooth. Because the patch is melted into the surrounding pavement, there is no cold joint around the edge for water to follow.

It works well for surface defects: small potholes in otherwise sound pavement, raised or sunken utility cuts, trip hazards, and rough seams. It is not a structural repair. If the base under the patch is soft or saturated, heating the top will not help, and the area needs a full-depth repair instead.

On a busy commercial property, infrared work is often quick enough to do in a single visit with minimal closure, which is part of its appeal.

Crack sealing: the cheapest repair that matters

Open cracks let rain into the base, and on clay subgrade that water is the root of most deeper failures. Sealing cracks while they are still narrow is the least expensive thing an owner can do to keep a driveway or lot from sliding toward full-depth patching.

Proper crack sealing uses a hot-applied rubberized sealant, not a thin cold filler from a jug. Each crack gets blown out with high-pressure air or dried with a hot air lance, then routed wider if needed so the sealant has enough depth and width, and applies the hot material in a band that slightly overlaps the edges. Cracks that are too wide or too broken for sealant are candidates for patching instead.

In the Houston area the best timing is often the cooler months, when cracks open wider and the sealant goes in with room to move in summer. Alligator cracking is not a crack sealing job; sealing individual cracks in a failed area only buys a little time.

Fixing the water source so the repair holds

Most repeat repairs on Houston-area asphalt trace back to water. A patch will fail the same way as the original pavement if the conditions that caused the failure are still there.

Look for where water stands after a heavy rain and where it runs. Common culprits include downspouts discharging onto the pavement edge, a low spot that holds water against a building or curb, turf and soil built up along edges so water cannot leave, clogged inlets and ditches, a culvert that has silted up, and irrigation spraying onto the pavement every morning.

Sometimes the fix is small: extending a downspout, cutting back a grass edge, cleaning a ditch. Sometimes it is adding a shallow swale, reshaping a low area during a patch, or installing a drain. A good repair proposal will name the water problem and say how it will be handled, or at least flag it for the owner.

• Downspouts and roof runoff dumping onto pavement edges
• Low spots and birdbaths that hold water for a day or more
• Grass and soil edges built up higher than the pavement
• Clogged roadside ditches, culverts or storm inlets
• Sprinklers wetting the pavement and its shoulders daily
• Tree roots breaking the edge and letting water under it

When repair stops making sense

Spot repair pays off while the damage stays confined to a few places on otherwise healthy asphalt. The math turns against it once patches start touching each other, when alligator cracking covers a large share of the surface, when the same areas fail again after being repaired, or when the whole surface is so oxidized that new patches stand out against crumbling pavement around them.

At that point the choice is usually between a mill and overlay, which removes and replaces the top layer after full-depth patches fix the worst areas, and full reconstruction, which rebuilds the base as well. Widespread base failure, heavy rutting and poor drainage built into the grade all point toward reconstruction.

A good contractor will say when repair money is being wasted. Ask for the repair option and the replacement option side by side, with a rough sense of how long each is expected to last, and decide with the full picture.

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