Concrete spalling is usually caused by water getting into the surface and then expanding, by a weak or overworked top layer, or by rusting steel close to the surface pushing the concrete apart. The result is flaking, chipping or pitting where pieces of the surface break away.
Spalling can look alarming, but it often starts at the surface. Knowing the likely cause helps you decide whether a repair is practical or whether something bigger is going on.
What Spalling Looks Like
Spalled concrete often has shallow, rough craters where the smooth top layer has popped off. Some areas look like they have been chipped with a hammer. Others look more like peeling or scaling across a wider area. You may also see loose flakes after a cold snap or heavy rain.
It shows up most often on driveways, steps, walkways and patios because those surfaces face the weather every day.
Common Causes
Water and Freezing
Concrete has tiny pores. When water soaks in and then freezes, it expands and pushes on the surface. North Carolina winters are mild compared with northern states, but freeze-thaw cycles still happen, and repeated cycles can wear down an exposed surface over time. De-icing salts can make this worse.
Finishing and Curing Problems
If the surface was overworked during finishing, or if extra water was added at the top, the upper layer can end up weaker than the concrete below. Poor curing in hot, dry or windy weather can have a similar effect. These issues may not show up until years later.
Rusting Reinforcement
When steel sits too close to the surface and moisture reaches it, the steel can rust and swell. That pressure can break off pieces of concrete above it. Rust stains or exposed metal are signs worth noting.
Can Spalled Concrete Be Repaired?
Often, yes. Small, shallow spalls can usually be repaired if the concrete underneath is sound and the cause can be managed. Repair generally involves removing loose material and restoring the damaged area with a suitable repair product.
Wider surface damage across a whole slab may be a better fit for concrete resurfacing, if the slab is otherwise stable. When spalling comes with deep cracks, sinking or crumbling through the slab, repair may not be enough, and replacement could be worth discussing.
Reducing the Chance It Comes Back
A repair lasts longer when the cause is addressed too. That might mean improving drainage so water doesn’t sit on the surface, limiting harsh de-icing products, or sealing the concrete where appropriate. Rust-related spalling needs a closer look, since the steel itself is part of the problem.
Because several causes can look alike, an in-person evaluation is the most reliable way to decide what to do. Our concrete repair services start with finding out why the surface is breaking down.
If you’re seeing flaking or chipped concrete around your Burlington home, we can take a look and explain which repair options make sense.
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