Maintenance
Why Is My Concrete Driveway Cracking? Causes & Fixes (2026)
By Fraser Coast Concreting · 14 June 2026
Quick answer
Concrete driveways usually crack from shrinkage as the slab cures, missing or poorly placed control joints, reactive clay soil movement (common around Maryborough and the Fraser Coast), tree roots, heavy loads or poor mix and curing. Fine hairline cracks are usually cosmetic, while wide, uneven or lifting cracks can be structural and should be assessed.
A few fine cracks in a concrete driveway are normal and usually nothing to worry about. Wider or uneven cracks can point to something underneath. This guide explains why concrete cracks, how to tell cosmetic from structural, and what you can do to prevent and fix it.
Why concrete cracks: the common causes
- Shrinkage. As fresh concrete cures and dries, it shrinks slightly. This is the most common cause of fine cracks and is largely unavoidable, but it’s controlled with proper joints.
- No or poorly placed control joints. Control joints are the cut lines that tell the slab where to crack. Without enough of them, or if they’re cut too late or too shallow, the slab cracks where it likes.
- Reactive clay soil movement. Much of Maryborough and the Fraser Coast sits on reactive clay that swells when wet and shrinks when dry. That movement flexes the slab and can crack it, especially if it wasn’t engineered for the soil.
- Tree roots. Roots growing under a slab lift and crack it over time.
- Heavy loads. A domestic slab not built for trucks, caravans or heavy machinery can crack under the weight.
- Poor mix or curing. Too much water in the mix, or letting the slab dry too fast in the sun and wind, weakens it and invites cracks.
- Lack of reinforcement. Without adequate steel mesh, a slab has little to hold it together when it moves.
Cosmetic vs structural cracks
Not all cracks are equal. Here’s a rough guide.
| Crack type | Likely cause | Concern level |
|---|---|---|
| Fine hairline cracks | Surface shrinkage | Usually cosmetic |
| Thin cracks along joints | Normal jointing | Usually cosmetic |
| Wide cracks (3mm+) | Movement, load, soil | Worth assessing |
| Uneven / lifting cracks | Soil movement, roots, settlement | Possibly structural |
| Cracks with displacement | Slab failure or footing issue | Get it assessed |
If one side of a crack sits higher than the other, the crack is widening, or it runs across the whole slab, it’s worth having someone look at it rather than just patching over it.
How to prevent cracking
Most cracking is designed out before the pour. A well-built driveway includes:
- Properly spaced and timed control joints, cut at the right depth so the slab cracks neatly where intended
- Adequate reinforcement (steel mesh, and bar where needed) to hold the slab together through movement
- A solid, well-compacted base so the slab is fully supported
- Engineering for reactive soil where the ground demands it
- Correct curing, keeping the slab moist as it sets rather than letting it dry too fast in our coastal sun and wind
- A mix suited to the job, without excess water
This is exactly why base prep, jointing and curing are not the places to cut corners, particularly on Fraser Coast clay soils.
Why the local climate matters
Around Hervey Bay and Maryborough, slabs face strong sun, drying winds and big swings between the dry season and heavy wet-season rain. Those moisture swings drive reactive clay movement, and fast drying after a pour encourages shrinkage cracks. A slab that’s properly jointed, reinforced and cured copes with all of this far better.
Fixing and resurfacing options
What’s right depends on the crack:
- Cosmetic hairline cracks: often just left, or sealed to keep water out and tidy the look.
- Minor cracks: can be filled and sealed to stop water getting in and worsening them.
- Surface wear with sound slab underneath: resurfacing can give a fresh, like-new finish over the existing slab, often more affordable than replacement.
- Structural cracking or failed slabs: sometimes the slab needs sections replaced or a full re-pour. This is the case when movement, footing problems or load have damaged the slab itself.
The key is getting the cause right. Resurfacing over a slab that’s still actively moving will just crack again, so it’s worth having the cause assessed first.
We repair and resurface driveways
If your driveway is cracking and you’re not sure whether it’s cosmetic or something more, Fraser Coast Concreting can assess it and recommend the right fix, whether that’s a simple repair, resurfacing or replacement. We work across Hervey Bay, Maryborough, Rainbow Beach and Tin Can Bay. Request a free quote here and we’ll take a look.