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(It’s Not the Asphalt)

Key Takeaways

If your driveway is only a few years old and it’s already cracking, sinking, or crumbling at the edges, the instinct is to blame the asphalt. Cheap materials, a bad mix, and a corner-cutting paving crew. Sometimes one or more of those may be to blame, it’s true. But in most cases, the asphalt itself is not the most likely culprit. In those cases, the real problem is almost always what’s happening underneath it, out of sight, before the first layer of asphalt was poured.

How an Asphalt Driveway Is Actually Built

An asphalt driveway is really three layers working together: a compacted sub-base of gravel, a base/aggregate layer on top of that, and the asphalt surface on top of everything. Asphalt handles compression (being squeezed) reasonably well. But asphalt cracks easily when it flexes, because it has very little tensile strength. Tensile strength refers to how much a substance resists being pulled apart.

Asphalt is a good material for driveways and parking lots, but like every building material, it has a correct way to use it, and many incorrect ways. 

The correct way to use asphalt is to put a base underneath that will keep the asphalt from flexing. Asphalt only flexes when something underneath it moves. That’s the explanation running through nearly every cause of cracking we list below: the surface cracks are a symptom of the problem, not the source of the problem.

The Real Reasons Asphalt Driveways Crack Early

1. Poor Sub-Base Compaction

If the soil or gravel base wasn’t compacted properly during installation, it shifts and settles over time — and the asphalt above the base goes up or down with it, since the asphalt can’t support itself. Trying to patch cracks caused by a poorly compacted base is “an exercise in futility,” and in severe cases, the only real fix is excavating the driveway down to the sub-base and rebuilding it properly. It’s hard to hear this when you spent money on a new or resurfaced driveway in the last several years, but the fact is that no amount of surface repair will change what’s happening a foot below the recurring cracks.

2. Poor Drainage and Grading

When water doesn’t drain away from the driveway, it collects on and beneath the surface, slowly eroding the base and creating voids that cause the asphalt above to sink into and crack. Improper slope and standing water are major drivers of long-term driveway failure. If you notice puddles that dry very slowly after a rainfall, that’s a sign of a drainage problem eroding your foundation under the ground.

3. Ice Formation

Water that gets into small cracks or porous spots in the asphalt expands when it freezes, forcing existing cracks wider and creating new ones as the freeze-thaw cycle repeats every winter. This is one of the most destructive forces on a driveway in Michigan. Sealant can slow moisture penetration and help prevent freeze-thaw-related cracks from forming. But if drainage is poor or the base is already compromised, freeze-thaw cycles will keep damaging the asphalt.

There are other ways that ice can damage your driveway that happen below the surface. When freezing temperatures penetrate fine-grained soil that has access to water, they can form an ice lens — a layer of ice that keeps growing by continuously drawing more water up from the soil below it. As that ice lens thickens, it heaves the soil — and everything on top of it — upward, sometimes by several inches, before dropping back down when it thaws. That repeated heaving and settling shears asphalt apart from underneath.

Fortunately, building the base of your driveway the right way will keep ice lenses from forming. If your driveway has already been laid down incorrectly, it will have to be entirely redone before you get relief from the heaving and subsequent cracking.

4. Heavy Vehicle Loads Exceeding the Driveway’s Capacity

Every driveway is built to handle a certain amount of weight, which dictates the requirements of the driveway’s design: its base, thickness, and material. Trucks, RVs, trailers, or construction equipment are heavy, beyond what many driveways were designed to carry. Parking such heavy vehicles and equipment stresses the base and the surface above it. 

5. Tree Roots

Roots seek moisture, and often enough they look for it under driveways. As roots thicken, they exert a surprising amount of pressure, often causing the driveway to be pushed up from underneath. Root intrusion is a common cause of cracking near mature trees that worsens as the root thickens.

6. Expansive Clay Soil

Clay-heavy soil absorbs water and swells, then dries out and shrinks, repeatedly stressing an improperly-laid driveway from below.  As long as a driveway sits on untreated expansive soil, cracks will keep reappearing no matter how many times the surface is patched.

7. UV Exposure and Natural Aging

Sun exposure gradually oxidizes the asphalt binder, drying it out and making it more brittle over time. This as a normal part of an asphalt driveway’s life cycle. It’s real, but on its own it typically takes years longer than 5 to cause serious cracking — if a driveway is failing this early, don’t look to oxidation for the primary cause.

Why Sealcoating and Patching Alone Don’t Solve Recurring Cracks

Patch companies fix what you can see: the crack itself. If the actual cause is a settling sub-base, poor drainage, or expansive soil, the patch holds for perhaps a season or two and then the same crack (or a new one nearby) shows up again. When the sub-base is the real problem, excavation and reconstruction is the only fix that actually holds. If you’ve resealed or patched the same section of driveway more than once, that’s usually the clearest sign the problem isn’t on the surface at all.

What an Excavation-First Fix Actually Looks Like

Instead of treating the symptom, an excavation-first approach addresses what’s actually causing the cracking:

This is the difference between resealing the same crack every couple of years and fixing the cause once.

Frequently Asked Questions

What causes potholes in asphalt driveways?
Aging, weather and stress cause small cracks int he asphalt. That allows water to seep into the base underneath. When that water freezes, it pushes both up and down, leaving a void  when it melts. As vehicles continue driving over the weakened, insufficiently-supported spot, pieces of asphalt break off entirely and a hole forms.

Why is my driveway sinking in certain spots?
Localized sinking almost always points to a void or soft spot in the base beneath the asphalt. These are usually from water erosion, poor original compaction, or soil movement. 

How long should an asphalt driveway last?
A properly installed asphalt driveway with a solid, well-drained base can last 15 to 20 years or more. If yours is cracking or sinking well before that, a problem with the base is the most likely reason.

Can a cracked driveway be fixed without a full replacement?
Sometimes, yes! We don’t want to sound too pessimistic, and we hope that you don’t have to redo your driveway so soon after having it done. Give us a call for a free consultation.

Does sealcoating stop cracks from coming back?
Sealcoating helps protect the surface from moisture and UV damage and can slow new cracking, but it doesn’t address problems originating below the surface. If the base, drainage, or soil is the actual cause, sealcoating will only buy time.

Get to the Actual Cause Before You Pay for Another Patch Job

If your driveway is cracking again despite being resealed or patched, the ground underneath it deserves a look before you spend money on the surface again. Markos Excavating offers excavation and grading evaluations to identify whether sub-base compaction, drainage, or soil conditions are the real reason your driveway keeps failing, and we can correct the actual problem instead of covering it up.

Contact Markos Excavating today to schedule a driveway evaluation.