Learn why new concrete cracks, when you should be concerned, and what to do about it.
Cracks in a new driveway, sidewalk, or patio can feel like a gut punch — especially when you’ve just paid for fresh, smooth concrete. Here’s the good news: hairline cracks in new concrete are normal.
The key is knowing when a crack is part of the natural curing process and when it’s a warning sign worth fixing before it turns into a costly repair, and it’s easier than you might think...
TL;DR
- Hairline cracks = normal, cosmetic.
- Wider than ⅛ inch = seal to prevent water damage, freeze‑thaw deterioration, rebar corrosion. (see the Two‑Quarters Test below)
- Common concrete crack causes: shrinkage, surface cracks from weather, settlement — not always poor workmanship.
In This Article
Why New Concrete Cracks
Concrete is strong but brittle. From the moment it’s poured, it begins shrinking and reacting to its environment. Even a perfectly poured slab will eventually develop cracks in fresh concrete.
Shrinkage Cracks
As concrete cures, it loses moisture and shrinks. If the surface dries faster than the inside (like a loaf of bread cracking on top as it bakes), internal stress causes small hairline cracks in new concrete. This is normal and doesn’t necessarily mean something went wrong.
Improper Mix Proportions
Too much water in the mix increases shrinkage, making cracks more likely. Even with good finishing, an overly wet mix can cause more noticeable new concrete curing cracks.
Curing Conditions
Hot, dry, or windy weather can cause surface cracks in new concrete by accelerating evaporation, aka drying too fast. Shading, misting, or curing compounds can help slow the process.
Settlement Cracks
Whether from erosion, poor compaction, or natural settling, when the soil beneath a slab shifts, the concrete above moves too. This creates settlement cracks in concrete that may widen over time.
Control Joints Not Doing Their Job
Control joints are intentional cuts that guide where cracks form. If they’re spaced incorrectly or cut too late, cracks may appear in unwanted areas.
When to Worry About Cracks
Not all cracks need to be fixed immediately. Cracks under ⅛ inch in width are often cosmetic, but wider than that deserve attention.
The Two‑Quarters Test
Place two quarters side‑by‑side over the crack (put George Washington’s faces together):
- Narrower than two quarters combined → Likely cosmetic, monitor over time.
- Wider than two quarters → Seal soon to prevent water intrusion and further damage.
Why width matters:
- In freeze‑thaw climates, water in the crack can freeze, expand, and push the crack wider.
- If water reaches the steel rebar inside, corrosion can weaken the slab from the inside out.
When to Fix vs. Leave Alone
| Crack Type | Action | Why? |
|---|---|---|
|
Hairline (<⅛ inch) |
Monitor only |
Often cosmetic; caulking may make it more visible |
|
Narrow (⅛–¼ inch) |
Seal / Fill / Caulk |
Prevents water intrusion and freeze‑thaw damage |
|
Wide (>¼ inch) |
Seal or consult a pro |
May indicate soil movement; caulking is essential |
|
Uneven crack (one side higher) |
Consult a pro |
May require leveling before caulking |
How to Fix Cracks in New Concrete
Tearing out and replacing an entire slab is the only way to make a crack completely disappear. But you can seal it with a flexible concrete caulk to keep water out and slow further damage.
DIY Repair
- Clean the crack. Remove dirt, debris, and loose concrete.
- If needed, grind the crack slightly so the repair material sits properly.
- Apply flexible concrete caulk (non‑sag or self‑leveling) for exterior slabs; it flexes with seasonal movement and seals against water.
Related Resource: How to Fix Cracks in Concrete
Pro Repair
- Faster, cleaner finish — especially for visible areas like driveways and patios.
- Ability to address underlying causes like settlement with leveling before sealing.
Related Resource: How A‑1 Keeps Cracks in Check With Concrete Caulking
Crack Prevention Tips for New Concrete
While you can’t stop all cracks in fresh concrete, you can reduce the risk:
- Plan pours for milder weather to minimize rapid surface drying.
- Ensure proper mix ratios with the right water content.
- Compact the base soil to reduce settlement.
- Use control joints spaced and cut correctly to manage where cracks form.
- Seal the slab after curing to reduce water penetration and freeze‑thaw stress.
Keep Your Concrete Protected
Regardless of how long your concrete has been around, cracks will only get worse if ignored. Whether you DIY concrete crack repair or hire a professional concrete repair service, sealing cracks now can prevent expensive replacements and extend the life of your slab.
A‑1 Concrete Leveling can help you get ahead of worsening damage with a clean, professional caulking job that’s built to last.
Request your free estimate today!
Still Deciding?
- Types of Concrete Cracks and What They Mean
- 5 Reasons to Repair Concrete Cracks
- How Much Does Concrete Caulking/Crack Repair Cost?
FAQs
Are hairline cracks in new concrete normal?
Yes. Most hairline cracks in new driveways, sidewalks, or patios form as the slab cures and are often purely cosmetic.
Why is my new concrete cracking already?
Concrete can crack within hours to weeks after pouring due to shrinkage, curing conditions, or soil movement, even in high‑quality work.
Should I seal/fill cracks in new concrete?
It's recommended to seal any crack wider than ⅛ inch to block water and prevent damage.
Do cracks mean my concrete is bad?
Cracking in new concrete does not necessarily mean the concrete is bad. Most cracks are part of the natural curing process and don’t indicate poor workmanship.
How do I prevent cracks in new concrete?
Control weather exposure during curing, avoid excess water in the mix, and ensure a well‑compacted base with properly placed control joints.
Request a Free Estimate
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